Demonstrative Thought: A Pragmatic View 9783110465808, 9783110464665

Table of contents :
Foreword
Contents
1 Introduction: What is Demonstrative Thought and How to Explain it?
1.1 Four properties of demonstrative thought
1.2 Demonstrative thoughts as attention-based mental activities with singular demonstrative contents
1.3 The mode/content proposal (and its limits)
1.4 Perceptualist approaches to demonstrative thought
1.5 Conceptualist approaches to demonstrative thought
1.6 An alternative proposal (and the road ahead)
2 Perceptualist Approaches to Demonstrative Thought
2.1 Perception as natural predication
2.2 Direct and indirect reference-fixing mechanisms
2.3 Attention-based perceptualism
2.4 Non-attentional perceptualism
2.5 Final remarks
3 Attention-based Perceptualist Theories of Demonstrative Thought
3.1 John Campbell
3.1.1 Experiential highlighting
3.1.2 Attention and feature binding
3.1.3 Experiential highlighting again
3.2 Wayne Wu
3.2.1 Wu’s argument against conscious attention as visual selection
3.2.2 Synchronic and diachronic phenomenal salience
3.2.3 The cognitive view of synchronic phenomenal salience
3.2.4 The agentive view of synchronic phenomenal salience
3.2.5 Attention as selection for action
3.3 James Stazicker
3.3.1 Conscious attention without synchronic phenomenal salience
3.3.2 Attention to thought
3.3.3 Demonstrative thought as cognitive attention
4 Non-attentional Perceptualist Theories of Demonstrative Thought
4.1 Joseph Levine
4.1.1 Intentionally mediated vs. direct meta-semantic mechanisms
4.1.2 Multiple object tracking and pre-attentive object representations
4.1.3 An attentional account of multiple object tracking
4.1.4 The evidence from subitizing
4.2 Athanassios Raftopoulos
4.2.1 Perception, attention and cognition
4.2.2 Three levels of visual processing
4.2.3 Proto-objects and the coherence problem
4.3 Mohan Matthen
4.3.1 Seeing objects versus seeing pictures
4.3.2 Motion-guiding vision and visual reference
4.3.3 Referring to objects without motion-guiding vision
4.3.4 Spatial significance
5 The Conceptualist Challenge to Demonstrative Thought
5.1 Introduction: the story so far
5.2 The conceptualist challenge to perceptualism: preliminaries
5.3 The orthodox view of practical knowledge
5.4 The conceptualist challenge revisited
5.5 On the idea of an ‘objective’ conception of space
5.6 The cognitive map strategy (and its limits)
5.7 Campbell on the role of physical objects in spatial thinking
6 The Pragmatic View of Demonstrative Thought (I): Practical Knowledge
6.1 Introduction: conceptualism and the explanatory gap
6.2 Practical and image-like knowledge
6.3 Practical knowledge and space
6.4 The historical-dispositional account (and its limits)
6.5 Two ways of knowing about speed (again)
6.6 The cognitive space
6.7 Stabilization and movement in cognitive space
7 The Pragmatic View of Demonstrative Thought (II): Object Representation
7.1 Introduction: practical knowledge and object representation
7.2 Bermudez’s object properties model of object perception
7.3 The graded knowledge approach: beyond perceptual sensitivity
7.4 Natural stabilization and the prefrontal cortex
7.5 A pragmatist answer to the conceptualist challenge
7.6 Natural de-stabilization
7.7 A new role for sortal concepts
7.8 Final considerations
Bibliography
Index

Citation preview

Felipe Nogueira de Carvalho Demonstrative Thought

Epistemische Studien

Schriften zur Erkenntnis- und Wissenschaftstheorie Herausgegeben von/Edited by Michael Esfeld, Stephan Hartmann, Albert Newen

Band 34

Felipe Nogueira de Carvalho

Demonstrative Thought A Pragmatic View

ISBN 978-3-11-046466-5 e-ISBN (PDF) 978-3-11-046580-8 e-ISBN (EPUB) 978-3-11-046479-5 ISSN 2198-1884 Library of Congress Cataloging-in-Publication Data A CIP catalog record for this book has been applied for at the Library of Congress. Bibliographic information published by the Deutsche Nationalbibliothek The Deutsche Nationalbibliothek lists this publication in the Deutsche Nationalbibliografie; detailed bibliographic data are available on the Internet at http://dnb.dnb.de. © 2016 Walter de Gruyter GmbH, Berlin/Boston Printing and binding: CPI books GmbH, Leck ♾ Printed on acid-free paper Printed in Germany www.degruyter.com

Foreword The research leading to this book was the result of a PhD program in Philosophy and Cognitive Science at the École des hautes Études en Sciences Sociales/Institut Jean Nicod in Paris, France, from September of 2008 to May of 2013. It has received funding from the European Community’s Seventh Framework Programme FP7/2007–2013 under ERC grant agreement n° 229441–CCC. I would like to thank my supervisor François Recanati for all his support and trust, as well as much needed pressure when the situation required it. Michael Murez also gave me valuable advice and countless comments throughout these years, and was an important help in writing this book. In addition, since the first months of my PhD my colleague Santiago Echeverri drew my attention to pragmatist-oriented explanations of mental phenomena, which was an important influence on my thinking about these matters. I have learned a lot from him during the years we shared an apartment in Paris, and I thank him for all the thought-provoking conversations we had. Finally, I thank all colleagues, researchers, employees, visiting professors and PhD students who made Jean Nicod a great place to work in: Reinaldo Bernal, Marie Guillot, Joulia Smortchkova, Dan Zeman, Benoît Conti, Denys Vinçon, Connor McHugh, Pierre Grialou, Hady Ba, Cintia Retz Lucci, Vincent Gaudefroy, Jérôme Dokic, Paul Égre, Sophie Bilardello, Elisabeth Pacherie, Tom Avery, Jérémie Lafraire and others too numerous to mention. During the last year of the PhD I have also benefited from a scholarship from the CIERA (Centre Interdisciplinaire d’Études et de Recherches sur l’Allemagne) for a visiting period at Ruhr-Universität in Bochum, Germany. For this, I thank Michael Werner and all at CIERA for support. Being in Bochum this last year was a great experience, and I thank Albert Newen for making this possible. I would also like to thank Luca Barlassina, Tomoo Ueda, Santiago Arango, Anika Fiebich, Nadine Overkamp, Lena Kästner, Markus Eronen, Anna Welpinghus, Nicole Bremkens, Nivedita Gangopadhyay and everyone at the department for a great stay. For a foreign student away from home, it is crucial to have the support of friends and family while working abroad. For this, I thank my family and friends for continuous love, trust and support: Eda, Julia and Rodrigo Nogueira, Humberto Carvalho, Cynthia Babo, Júlio Agnelo, Lorena Morato, Pedro Machado, Alina Müller, Fernanda Ribas, Marc Crean, Gui Perdigão and Thiago Galery.

Felipe Nogueira de Carvalho

Contents Foreword | v 1

1.3 1.4 1.5 1.6

Introduction: What is Demonstrative Thought and How to Explain it? | 1 Four properties of demonstrative thought | 1 Demonstrative thoughts as attention-based mental activities with singular demonstrative contents | 5 The mode/content proposal (and its limits) | 8 Perceptualist approaches to demonstrative thought | 12 Conceptualist approaches to demonstrative thought | 17 An alternative proposal (and the road ahead) | 21

2 2.1 2.2 2.3 2.4 2.5

Perceptualist Approaches to Demonstrative Thought | 25 Perception as natural predication | 25 Direct and indirect reference-fixing mechanisms | 29 Attention-based perceptualism | 31 Non-attentional perceptualism | 38 Final remarks | 41

3

Attention-based Perceptualist Theories of Demonstrative Thought | 43 John Campbell | 43 Experiential highlighting | 43 Attention and feature binding | 49 Experiential highlighting again | 53 Wayne Wu | 58 Wu’s argument against conscious attention as visual selection | 58 Synchronic and diachronic phenomenal salience | 59 The cognitive view of synchronic phenomenal salience | 62 The agentive view of synchronic phenomenal salience | 67 Attention as selection for action | 71 James Stazicker | 76 Conscious attention without synchronic phenomenal salience | 76 Attention to thought | 78 Demonstrative thought as cognitive attention | 81

1.1 1.2

3.1 3.1.1 3.1.2 3.1.3 3.2 3.2.1 3.2.2 3.2.3 3.2.4 3.2.5 3.3 3.3.1 3.3.2 3.3.3

viii | Contents

4 4.1 4.1.1 4.1.2 4.1.3 4.1.4 4.2 4.2.1 4.2.2 4.2.3 4.3 4.3.1 4.3.2 4.3.3 4.3.4 5 5.1 5.2 5.3 5.4 5.5 5.6 5.7 6 6.1 6.2 6.3 6.4 6.5 6.6 6.7

Non-attentional Perceptualist Theories of Demonstrative Thought | 90 Joseph Levine | 90 Intentionally mediated vs. direct meta-semantic mechanisms | 90 Multiple object tracking and pre-attentive object representations | 95 An attentional account of multiple object tracking | 99 The evidence from subitizing | 103 Athanassios Raftopoulos | 108 Perception, attention and cognition | 108 Three levels of visual processing | 113 Proto-objects and the coherence problem | 117 Mohan Matthen | 120 Seeing objects versus seeing pictures | 120 Motion-guiding vision and visual reference | 122 Referring to objects without motion-guiding vision | 129 Spatial significance | 133 The Conceptualist Challenge to Demonstrative Thought | 138 Introduction: the story so far | 138 The conceptualist challenge to perceptualism: preliminaries | 142 The orthodox view of practical knowledge | 153 The conceptualist challenge revisited | 157 On the idea of an ‘objective’ conception of space | 160 The cognitive map strategy (and its limits) | 168 Campbell on the role of physical objects in spatial thinking | 175 The Pragmatic View of Demonstrative Thought (I): Practical Knowledge | 180 Introduction: conceptualism and the explanatory gap | 180 Practical and image-like knowledge | 188 Practical knowledge and space | 194 The historical-dispositional account (and its limits) | 198 Two ways of knowing about speed (again) | 206 The cognitive space | 210 Stabilization and movement in cognitive space | 215

Contents | ix

7 7.1 7.2 7.3 7.4 7.5 7.6 7.7 7.8

The Pragmatic View of Demonstrative Thought (II): Object Representation | 222 Introduction: practical knowledge and object representation | 222 Bermudez’s object properties model of object perception | 225 The graded knowledge approach: beyond perceptual sensitivity | 235 Natural stabilization and the prefrontal cortex | 239 A pragmatist answer to the conceptualist challenge | 244 Natural de-stabilization | 251 A new role for sortal concepts | 255 Final considerations | 259

Bibliography | 263 Index | 273

1 Introduction: What is Demonstrative Thought and How to Explain it? 1.1 Four properties of demonstrative thought The simplest way to introduce the notion of a demonstrative thought is by contrasting it with what is called in the literature a “descriptive thought”. To illustrate with an example, let’s suppose that on purely general considerations I think that ‘the winner of the Olympic 100m dash is very fast’. In this case, I think of a man through the description ‘the winner of the Olympic 100m dash’, and the thought will refer to a particular man (if it refers at all) in virtue of this man satisfying the descriptive condition specified in the thought, of being the winner of the Olympic 100m dash.1 But on the other hand philosophers have always drawn attention to a more ‘direct’ way in which our thoughts can be about particular objects, based on our bearing a more intimate relation to them. A paradigmatic example would be a perceptual demonstrative thought like ‘this man is very fast’, which I could have on the basis of perceiving a particular man in front of me running very fast. In this case, even if the man I perceive happens to be the winner of the Olympic 100m dash – so that both the descriptive and the demonstrative thought refer to the same man – the crucial difference between the two lies in the way the intentional object of the thought is determined. To put in Kent Bach’s influential terminology, a demonstrative thought is one where the object of thought is determined relationally, via perception, as opposed to satisfactionally, via a descriptive condition conceptually articulated in the thought.2 So the intentional object of my demonstrative thought is the man I bear a perceptual relation to, independently of any descriptive material I happen to associate with him. Therefore, it would be wrong to take perceptual demonstrative reference to be determined by a description like ‘the x perceived by me’ or something along these lines. All that matters for perceptual demonstrative reference to take place is that the subject be in a perceptual relation to the object, not that he be able to conceptually articulate it in thought. As Tyler Burge puts

|| 1 To be more precise, we would need to include in this descriptive condition all relevant parameters for fixing the thought’s truth-conditions, such as the time of the thought etc. To simplify matters these parameters will be left out of the present definition, but should be kept in mind. 2 See Bach 1987: 12.

2 | Introduction: What is Demonstrative Thought and How to Explain it?

it, perceptual demonstrative thought places the thinker in “an appropriate nonconceptual, contextual relation to the object [the thought] is about”, and it is precisely this relation that determines which particular object the thought concerns.3 This short account gives us two important properties of demonstrative thoughts. First of all they have singular contents, which represent particular objects in the world. Of course, in putting forward this property as being distinctive of demonstrative thought I am deliberately ignoring what philosophers have called ‘type-demonstratives’, which pick out properties rather than objects. To illustrate with an example, if I look at a colored wall and think ‘I want that color for my room’ I am here referring to a type of color: I have no intentions to peel off the paint from that particular wall and take it to my room.4 But as my main interest in this book is to explain our capacity to think about particular objects in the world, I will restrict myself to demonstrative thoughts about particulars and leave type-demonstratives for another occasion. This allows us to safely take singular content’ as a distinctive property of demonstrative thoughts. In addition to singular contents, the second property we need to acknowledge is that demonstrative thoughts have perceptual-relational reference-fixing mechanisms. As we’ve seen above this is what distinguishes demonstrative from descriptive thoughts, for even if both refer to the same particular object, only demonstrative thoughts pick out their objects in a relational manner, putting the thinker in a perceptual relation to the object the thought concerns. But in order to fully capture what is special about demonstrative thought, we need more properties: a third important property is their languageindependence. What this property seeks to capture is that even if I have introduced demonstrative thoughts through their linguistic expression, i.e., in terms of a sentence like ‘this man is very fast’, the linguistic expression is not essential to the thought. What I am interested in explaining is a more general capacity, to cognitively single out particular objects perceived in our external environment so that they can become the subject matter of thoughts. Although the thought could eventually be expressed in the form of a sentence like ‘this man is very fast’, we should be able to account for the cognitive capacities that make this thought possible without presupposing a capacity to linguistically articulate it.

|| 3 See Burge 1977: 346. 4 The example comes from Levine 2010: 186.

Four Properties of Demonstrative Thought | 3

In this context, the property of language-independence may be understood as a methodological assumption, as emphasized by Raftopoulos and Müller: When we examine demonstratives we do not mean the linguistic expressions of the form “that X” (...) but the mental state that could be linguistically articulated by such demonstrative expressions. Such a mental state occurs when attention is drawn by some object and we focus upon it; we are in an internal mental state whose content is somehow causally related to the object and its features. Were we asked to report what we are attending to, we would have replied “that X” pointing to the object. Raftopoulos & Müller 2006: 253

‘Language-independence’ in this sense means that the study of demonstrative thought can be carried on independently of the study of the canonical linguistic expression of the thought, through an explanation of how the subject’s mental state can be about particular objects in the world. And the methodological assumption is that we should be able to explicate this cognitive capacity independently of the subject referring to the object with the demonstrative pronoun ‘that’. Further on, the passage above highlights yet another important feature of demonstrative thoughts: that the mental states we use to characterize them are attention-based states, which depend (in one way or another5) on the allocation of attention to the object the thought concerns. Without attention, we would not be able to think demonstratively about an object of visual perception.6 This is on the right track, but acknowledging these four properties does not yet capture what is distinctive about demonstrative thought. For the perceptual states underlying these thoughts may also be characterized in terms of the properties above, i.e., in terms of singular contents, perceptual-relational reference-fixing mechanisms, language-independence and based on attentional mechanisms.7 But intuitively the perceptual state and the demonstrative mental state are not identical. It seems possible to perceive and attend to things without thinking about them, like when we are in a very boring lecture with our eyes fixed on the speaker, but thinking about items in a grocery list or trying to solve a philosophical problem of our own. In addition, we can also think demonstra-

|| 5 This point will be discussed extensively in chapters three and four. 6 As demonstrated by patients with blindsight; see chapter 2 for further details. 7 This is not to say there could not be perceptual states in the absence of attention; but the fact that at least some perceptual states are attention-based is enough to establish the point that these properties fail to fully distinguish perceptual states from demonstrative mental states.

4 | Introduction: What is Demonstrative Thought and How to Explain it?

tively about a more restricted subset of things we can perceive and attend to; I can perceive and attend to both the speaker and the microphone in the boring lecture, while thinking ‘that one’ of only one of them. This last point may be disputed; one might say, for example, that attending is already a form of thinking, so that when I attend to the speaker in the boring lecture I am already thinking about him, even if I also happen to be thinking about other things at the same time. In a similar vein, one could also say that when I attend to both the microphone and the speaker I am already thinking about both of these things, even if I am explicitly articulating only a subset of my thoughts (those that concern one object rather than the other). If this is true, then perhaps the relation between demonstrative mental states and attentional perceptual states should be conceived as the relation of identity: thinking demonstratively about x amounts to attending to x. As James Stazicker puts it: I take it that thoughts need not be verbal or otherwise articulated. If you simply notice one of the intersections in [a diagram], that amounts to thinking of the intersection. Stazicker 2012: 15

Indeed, perhaps we can understand ‘noticing’ something as a way of thinking about it, in some sense or another of ‘thinking’. This is especially true when we focus on cases where we consciously allocate our attention to objects, an act that is under volitional and cognitive control and whose phenomenology cannot be so easily divorced from the phenomenology of thinking about objects.8 But even granting this point should not lead us to identify demonstrative mental states with attentional perceptual states: for while noticing may be a form of demonstrative thinking, it is not the only form of demonstrative thinking there is. If I perceive a teacup in my kitchen counter and think thoughts like ‘this cup was given to me by my grandmother last Christmas’, ‘this cup would look great in my sister’s teacup collection’, or ‘this cup is too big to fit on that plate by the sink’, I am doing more than just noticing the cup or attending to it. I am also bringing up memories of the cup, imagining it in my sister’s cupboard along her other teacups, visualizing it on top of another plate I see, and so on. Although these thoughts bear of course important relations to my noticing and attending to the cup, they are not identical to it. We could say that these are thoughts that my noticing the cup makes possible. This gives us good reasons to keep the distinction between being in attention-based perceptual states causally connected to objects in the world, and

|| 8 This last point is more controversial. It will be discussed extensively in chapter three.

Demonstrative thoughts as attention-based mental activities | 5

having demonstrative thoughts about these objects. But as both perceptual and demonstrative mental states may be characterized in terms of the same properties, i.e., as having singular contents, perceptual-relational reference-fixing mechanisms, being attention-based and language-independent, we must be more specific about demonstrative thoughts and their relations to perceptual states. In other words, we must be able to make sense of the idea that having a demonstrative thought involves being in a certain mental state M that bears some relation R to an underlying perceptual state P, without being identical to it (see schema below). The remaining tasks would be to provide an adequate characterization of M, specify which relation R it bears to the perceptual state P, as well as explain how P in turn connects to the particular object O in the external world (relation R’):

M (demonstrative mental state)

!• p

(underlying perceptual state)

~· 0

(external obj ect)

Fig. 1: Simple relation between demonstrative mental states and perceptual states

1.2 Demonstrative thoughts as attention-based mental activities with singular demonstrative contents Let us begin by focusing on M; one idea that naturally comes to mind is that M must be some sort of belief state; this is intuitively suggested by the usual stock of examples put forward in the literature, usually in the form of judgments like ‘this man is fast’, ‘this chair is brown’, etc. Based on the form of the examples and having language-independence in mind, we might think that M must be the

6 | Introduction: What is Demonstrative Thought and How to Explain it?

belief state one is in upon perceiving a certain object as having a certain property F, which could lead one to make the corresponding judgment: ‘this is F’.9 But although it is clear that having beliefs about external objects and judging them to have certain properties constitute an important class of demonstrative thoughts, I also find this way of putting things somewhat restrictive. For it tends to overlook the fact that when we perceive objects in the world we are not only in a position to have beliefs and make judgments about them, but also to cognitively engage with them in various ways (in a sense that will soon be clarified). And my suggestion is that we need a notion of demonstrative thought that is comprehensive enough to capture the full range of cognitive engagements that perception of objects puts us in a position to do. To be clear, I am not denying the obvious point that perception presents us with objects as bearing certain properties (colors, shapes, sizes etc.), and that upon being presented with objects in this manner we may directly (noninferentially) come to have beliefs about how things are in our immediate external environment. I am also not denying that perceptual states bear interesting and important relations to belief states and to perception-based judgments, which need to be maintained if we want to do a sound epistemology of perception and perceptual beliefs. The point I am raising is that having beliefs and making judgments are not the only things perception puts us in a position to do, and that we should not model demonstrative thoughts exclusively on property attributions of the form ‘this is F’. Obviously, when I perceive a chair that looks brown to me I may come to believe that the chair is brown (in the absence of collateral information to the contrary), and eventually make the judgment ‘this chair is brown’. But I can also cognitively engage with the chair in various ways, for example: plan various actions in relation to it, visualize the chair from other perspectives, imagine what it would look like with different surface properties, make suppositions about its hidden properties, estimate whether it would fit in the space between the couch and the table, rotate it in my mind through visual imagery, and so on. These are all different ways of cognitively engaging with the chair, to have various attention-based mental activities that concern just this particular chair. And the point is that engaging in these activities is not just a matter of having beliefs about the chair (although it may of course depend in interesting ways on having some beliefs about the chair). This suggests that it would be desirable to have a

|| 9 I am thinking of ‘judgment’ here as some sort of act on the part of the subject: to assert, or judge, that things are thus and so in speech or thought. So the judgment, qua act, is distinct from the belief state that gives rise to it.

Demonstrative thoughts as attention-based mental activities | 7

broader notion of demonstrative thought, which could encompass a wider range of mental activities that perception of objects put us in a position to do. What unifies these mental activities is precisely their common singular demonstrative content, which represents the object that is the target of the mental activities in question. With these ideas in mind, my suggestion is that we look at demonstrative thoughts as ‘attention-based mental activities with singular demonstrative contents’. The notion of a ‘mental activity’ employed here is broad enough to cover the whole range of cognitive engagements with objects I have emphasized above, allowing us to extend this notion beyond the more simple cases of perceptual judgments and beliefs. The singular element in the definition indicates that what is represented in the mental states underlying these activities are particular objects (as opposed to properties, events, etc.), while the demonstrative element tells us that their intentional objects are determined relationally via perception. Combined with the methodological assumption of languageindependence and the fact that these activities depend (somehow) on the allocation of attention, this definition captures very well the four properties of demonstrative thoughts previously alluded to. But before we proceed, one small clarification: isn’t it a bit redundant to explicitly mention both the ‘attention-based’ and the ‘demonstrative’ elements in the definition above? After all, attention is quite plausibly the perceptual relation that puts us in contact with objects in the world, so when we say that these mental states have ‘demonstrative’ contents, we are already presupposing an attentional relation between the subject of the mental state and an external object. This means that characterizing demonstrative thoughts as ‘mental activities with singular demonstrative contents’ would suffice for present purposes. The explicit mention of ‘attention-based’ adds nothing to it. But if we say this, we are already making a substantial commitment regarding the role of attention in demonstrative thought. As we shall see in more detail in chapters two and three, there are various ways in which demonstrative thought could be based on the allocation of attention, besides attention being the fundamental perceptual relation that puts us in contact with objects. If we say, for example, that what accounts for the demonstrative element in these mental activities is some kind of non-attentional perceptual relation (as will be argued in chapter three), then it is a non-trivial claim to say that besides having demonstrative contents these activities are also based on the allocation of attention. So another advantage of this definition is that it allows us to leave open the nature of the relation between attention and demonstrative thought, while still

8 | Introduction: What is Demonstrative Thought and How to Explain it?

making clear that (some) relation between the two must hold if demonstrative thought is to be possible. Further on, this definition allows us to make sense of the idea that engaging in these mental activities is not identical to being in perceptual states, but are things that perception makes possible. That is to say, judging ‘this chair is brown’, mentally rotating it in one’s mind through visual imagery, imagining it painted white, wondering whether it is made of plastic or wood, supposing it is made of plastic or wood, planning an intentional action in relation to it, etc., are all things that one’s perception of the chair puts one in a position to do. If it weren’t for the perception, one would not be able to do these things in relation to that particular chair: to judge that it is brown, to wonder whether it is made of wood, to mentally rotate it in space, to imagine it painted in white, etc. Saying that perception puts us in a position to engage in these activities, however, is not the same as saying that the perceptual state is identical to the corresponding singular demonstrative mental state. Rather, the perceptual state makes a whole range of object-directed mental activities possible. We thus arrive at an answer to one of the two questions that opened this chapter: demonstrative thoughts are attention-based mental activities with singular demonstrative contents. But what is it to explain it? Before I explore some ways of answering this question, I would like to briefly consider an alternative way of accounting for the broader notion of demonstrative thought I am after – based on the distinction between ‘mode’ and ‘content’ – and sketch some considerations as to why I find this suggestion problematic.

1.3 The mode/content proposal (and its limits) In the previous section I insisted that we should acknowledge a broader range of cognitive engagements with objects as instances of demonstrative thought. I have also said that what unifies these cases is their common singular demonstrative content. But if that is so, then perhaps we could say that engaging in these different activities is a matter of entertaining a common demonstrative content under different psychological modes, in a manner similar to that argued by François Recanati (2007).10 Just as I can believe, upon perceiving an object, that it has a certain property, I can also imagine that it does, and in each case I

|| 10 I do not suggest that this is exactly what Recanati would say in these cases. I am only interested in seeing how far his model takes us in understanding this broader notion of demonstrative thought.

The mode/content proposal (and its limits) | 9

would entertain a demonstrative content under a different psychological mode, such as BEL [this chair is brown] for the belief mode, IMAG [this chair is brown] for the imaginative mode, and so on. Although the attributed property is different in each case, both share a singular demonstrative content that refers to ‘this (perceptually presented) chair’. But here’s why I believe it would be difficult to make this proposal work. First of all, it is unclear how we could account for cases of demonstrative visual imagination, a special case of imagination with a demonstrative component that is grounded on a particular object in the subject’s external environment: this is the case where I fixate my eyes on a brown chair while imagining its surfaces being painted white. One problem is that what connects representational content to the world around the perceiver, in Recanati’s picture, is the psychological mode, which determines the situation against which the content is to be evaluated. The fact that it is a perception, for example, determines the subject’s perceptual situation as the relevant point of evaluation for the content in question: that is to say, the objects and properties around the perceiver at the time of the perception, causally responsible for the perception in question.11 What makes content demonstrative, in other words, is the perceptual mode. This explains how a belief that is directly (i.e., non-inferentially) based on perception will also concern the objects and properties perceived around the subject at the time of the perception: these have already been (implicitly) secured as the intentional objects of perception via the perceptual mode. Imagination, in contrast, shifts the relevant point of evaluation to an imagined situation, so that a content like ‘this chair is white’ entertained under the imaginative mode will concern an imagined situation where the chair has a property it does not actually have.12 But this fails to capture the way demonstrative visual imagination has as its intentional object this perceptually presented chair, which is imagined as white as we keep our attention focused upon it. If we embed the content ‘this chair is white’ in the imaginative mode, we would lose the demonstrative connection to the perceptually presented chair. So if we want to maintain Recanati’s original idea of maintaining the demonstrative connection via mode, we would have to introduce some kind of mixed mode, with both perceptual and imaginative elements, where the perceptual element would be responsible for fixing the referent of the demonstrative ‘this chair’, and the imaginative element would indicate that the predicate ‘…is white’ is applied only in imagination. Or, alternatively, we could have a hierar|| 11 Recanati 2007: 130-135. 12 Recanati 2007: 286ff.

10 | Introduction: What is Demonstrative Thought and How to Explain it?

chy of modes, where the perceptual mode would be embedded in a higher-order imaginative mode, which attributes in imagination a property to an object that was secured by the lower-level perceptual mode (a function of this higher-order imaginative mode would be to ‘suspend’ the properties attributed to the chair in perception, so that contrary properties could be attributed to it in imagination). But these moves would require some substantial tinkering with Recanati’s original theory, and it is not immediately clear what the overall picture would look like once we allow more than one mode to operate simultaneously on distinct components of representational content, or how points of evaluation could be simultaneously determined in a multiple hierarchy of modes. In short, perhaps these are not insurmountable problems, and perhaps they could eventually be solved with enough technical tweaking. But even if we manage to solve these problems, there are cases of dynamic demonstrative visual imagery that are more difficult to be accommodated in a mode/content framework. Suppose, for example, that I perceive a brown chair from a certain perspective as having its front side facing me. I take it that a theorist like Recanati would not be willing to include a property like ‘having its front side facing me’ in the content of the perception. This is quite plausibly an aspect of the particular perspective from which I perceive the chair, and although we always perceive objects from a certain perspective, it would be wrong to include this perspective in the content of what is perceived. This is exactly why the notion of a psychological mode is useful in these cases, as it allows us to capture the inherent perspective-dependence of perception without saddling representational content with it. The fact that it is a perception determines the situation of evaluation as the world around the perceiver from her particular perspective, where objects are perceived from a certain angle, at a certain distance, and so on. So when I perceive a brown chair from the front, the property of ‘having its front side facing me’ is not part of the content of perception. It is just a matter of the perspective I happen to occupy in relation to the chair. But if this is true, then what should we say about a case when I mentally rotate the chair through visual imagery around its vertical axis, and come to visualize it as having its back side facing me? It is not the case that my perspective is being shifted in imagination, say, to a different perspective where I am placed on the other side of the chair.13 I still perceive the scene from the same perspec-

|| 13 This is something we can do, but it is a different phenomenon. Upon perceiving a visual scene, we can imagine what the scene would look like if we were placed differently in relation to it, an instance of a psychological ability Campbell calls “spatial decentering” (Campbell

The mode/content proposal (and its limits) | 11

tive: the only difference is that I now visualize the chair as having its backside facing me. But when I visualize it in this way, do I attribute to the chair the property of having its back side facing me, so that the imagined content would be something like IMAG [this chair has its backside facing me]? If we had good reasons to resist this analysis in the normal perceptual cases, we should also resist it in the demonstrative imagery case. When I mentally rotate the chair in my mind through visual imagery, I do not attribute to it a new property it did not have before (namely, the property of having its back side facing me); in fact, I assume that the chair retains all the properties attributed to it in visual perception. Rather, I am just visualizing the chair as if it were differently placed in the room. But doing so is not just a matter of attributing properties to it in imagination. To see why, suppose we say that demonstrative visual imagery involves attributing to objects properties they do not actually have, which are attributed to it only “in our mind’s eye”. So if I now visualize the chair slowly rotating around its vertical axis until I visualize its backside facing me, is it the case that for every different angle in which the chair is visualized, there is a different property being attributed to it through demonstrative visual imagery? Or does imagery attributes one single property to the chair, namely, the dynamic property of “rotating”, which it then ceases to have once it stops rotating and is visualized with its back side facing me? This does not seem right. It seems I am just visualizing the chair being given to me in a slightly different manner, in a way that is crucially dependent on my perception of the chair. That is to say, the way I rotate the chair in my mind and how I visualize its backside depends on some properties of the chair that are made available to me in perception: its size and position in the room, the volume it occupies, the spatial and structural relations between its different parts, etc. If I attribute any properties to the chair at all, these are the properties I attribute to it. These properties constrain how I visualize the chair rotating in my mind around its vertical axis. Through a practical grasp of these structural properties I am able to extrapolate on visual information that is currently given to me in perception in order to rotate the chair in my mind, where the content of my visualization is crucially dependent on the content of my perception.14 But it

|| 2002: 183-4); but this is not what is going on in this case, where I maintain my perspective in relation to the object. 14 It is not a general point that perception must always constrain visual imagery in this sense; we are normally able to rotate the chair freely in our minds in ways that do not cohere with the way the chair is actually perceptually presented to us. We can imagine it flying around the room, as having legs that alternately stretch and shorten, etc. But for the purposes of the task

12 | Introduction: What is Demonstrative Thought and How to Explain it?

is not clear how to cash out these more complex cases of dynamic demonstrative visual imagery within the mode/content distinction. In any case, these questions deserve further discussion, which unfortunately is beyond the scope of this book. The point of this brief detour was only to show that enlarging the class of demonstrative thoughts as I have been suggesting is not just a matter of embedding demonstrative contents under a variety of psychological modes. Although the mode/content framework is very well fit to capture simple cases of visual perception, episodic memory, and (nondemonstrative) imagination, it is not clear how cases of demonstrative visual imagination and dynamic demonstrative visual imagery could be accommodated within this framework. But since we have good reasons to take them to be instances of demonstrative thought as well, this casts doubt on the adequacy of the mode/content framework for present purposes. Once again, these arguments do not purport to show that the framework could not in principle be extended in order to cover these more problematic cases: but it certainly raises some significant difficulties.

1.4 Perceptualist approaches to demonstrative thought To go back to our main discussion, I have opened this chapter with the following questions: what is demonstrative thought and what is it to explain it? After going through the first three sections of the chapter we are now in a position to offer at least a preliminary answer to these questions. Demonstrative thoughts, I suggested, are attention-based mental activities with singular demonstrative contents: judging an object of visual perception to have a certain property, visualizing it from a different angle, imagining it with different surface properties, rotating it in our minds, wondering about its hidden properties, etc. What unifies these activities is their common singular demonstrative content, which represents the object of visual perception they are targeted at. So if we want to explain our capacity to engage in these sorts of mental activities with singular demonstrative contents, we should be able to elucidate both the singular and the demonstrative elements that characterize this content, namely: 1. The Demonstrative Question: how do our mental states connect to the particular objects in the world they are targeted at?

|| at hand, where we are concerned with the possibility of placing the chair differently in the room, it does matter that perception constrains visual imagery in this sense.

Perceptualist approaches to demonstrative thought | 13

2. The Singular Question: what makes it the case that these mental states represent particular objects, rather than properties, events, or some other suitable candidate for the representata of these mental states? Any putative theory of demonstrative thought should be able to elucidate these questions, as well as specify the role of attention in making these activities possible. But how should we go on about elucidating them? In order to structure the logical space that shall be explored in the course of this book, I would like to introduce two main approaches we can take towards the study of demonstrative thought: perceptualism and conceptualism. Let’s begin with perceptualism. Perceptualism starts out with two very plausible ideas, which emerge quite naturally from everything that has been said so far concerning the relation between perception and demonstrative thought. The first idea is a general methodological constraint we may call nonconceptual basis. It states that an explanation of demonstrative thought should be sought at the more primitive level of perception, through an account of how visual perception put us in a direct (i.e., conceptually unmediated) contact with objects, thus making demonstrative thought about these objects possible. The idea is the following: as we have seen before, demonstrative thought may be understood in terms of attention-based mental activities that are appropriately based on a perception of the relevant object. This leads us to posit an underlying perceptual state P as the initial base state, which explains how demonstrative thought is possible. If this is true, then perceptualism argues that the basic task of a philosophical account of demonstrative thought should be to explain how the perceptual state itself already secures the object the thought concerns, through perceptual referential mechanisms that select their objects in conceptually unmediated ways. Perceptualism thus claims that the perceptual states upon which demonstrative thoughts are based already have singular demonstrative contents. The corresponding demonstrative thought would then ‘inherit’ the intentional object of perception, which has already been secured at the base level by the perceptual mechanisms in question.15 For unless we are able to show that percep-

|| 15 The notion of ‘inheritance’ may be understood in Burge’s sense, when he talks of demonstrative applications in thought or language – like singling out an object with the demonstrative ‘that one’ – “inheriting”, or “taking over”, the referents of their counterpart perceptual applications. These perceptual applications are supposed to be the processes and mechanisms

14 | Introduction: What is Demonstrative Thought and How to Explain it?

tion has its own means of picking out objects in the world, we will fail to make sense of the claim that it is perception what put us in contact with external objects, as opposed to concepts in the mind of the thinker. But since we have already granted that an important property of demonstrative thoughts is the relational, perceptual character of their reference-fixing mechanisms, this is not acceptable. Therefore, any putative explanation must start out by showing how perceptual states, qua initial base states, already have singular demonstrative contents. This idea is nicely captured in the following passage from Raftopoulos and Müller: The intentional relation between perception and events in the world, that is, the ofrelation between perceptual mental states and events, should be sought at the level of the direct causal relation between perception and the world. Therefore, we need to show that the reference to objects and some of their properties emerges in conceptually unmediated causal ways from our viewing a scene, and that this referring induces in us perceptual states with nonconceptual content. Raftopoulos & Müller 2006: 253

The second idea behind perceptualism besides nonconceptual basis is that of visual selection; roughly speaking, the idea is that what explains nonconceptual basis cannot be only a general capacity to “perceive” objects, in some loose sense of “having the object in one’s field of vision”, but a capacity to visually select just certain objects among others in one’s external environment. For example, if I gaze distractedly out of the window of my office into the urban landscape below, a number of different buildings may fall within my visual field, but there is no particular building that stands out among the others: my experience, to borrow John Campbell’s term, is as of a “sea of buildings”.16 As long as my experience remains like this, I am in no position to judge, of a particular building, that it has a certain property F, to plan a walking route to it, to estimate whether it is taller than the building I am currently in, to visualize it in a different color, and so on. It is only when a particular building is visually selected in my perception that I am in a position to have demonstrative thoughts about it. Therefore, it seems plausible to suppose that what connects demonstrative thought to external objects is a perceptual ability to visually select these objects, which puts us in a position to cognitively engage with them in various ways.

|| responsible for forming perceptual representations of objects in the visual system (Burge 2010: 546) 16 Campbell 2002: 8.

Perceptualist approaches to demonstrative thought | 15

Indeed, when we look at the relevant literature, there are various colorful metaphors that seek to emphasize the importance of visual selection in explaining our capacity to have demonstrative thoughts about objects. In Kaplan’s famous account of demonstratives, for example (1989a), we find the ‘appearance’ of an object as a perceptual element brought in to complete the ‘character’ of demonstrative expressions, so as to determine, in a context, the semantic content of the demonstrative expression tokened in that context. Now, even if the semantics of demonstrative expressions is not our main issue here (as I have already made clear with the property of language-independence), what is important here is that Kaplan asks us to conceive of the ‘appearance’ of an object as if it were “a picture with a little arrow pointed at the object”, to emphasize the fact that it is this act of visual selection, symbolized by an arrow intervening in experience in order to “mark” the relevant object, that ultimately determines the singular content of the demonstrative.17 Other philosophers have opted instead for the metaphor of “highlighting”, as if upon visual selection an object becomes emphasized, highlighted in bright colors by a yellow marker, somehow marked as more salient relative to other objects around it. Here, for example, is how John Campbell describes it: Suppose you are in a lecture and your mind wanders off a little, the lecture fails to grip. So you look around idly at other people in the audience, your gaze resting now on this person, now on that. In effect, you highlight now one aspect of your experience, now another. In effect, you put a yellow highlighter now over one or another part of your visual experience, as you wonder about this or that person. Campbell 2002: 4

A metaphor that is also employed by Joseph Levine: The analogy I like is between attention and the ‘select’ function in Word; highlighting the relevant text is a way for the program to select it for further processing, like moving, deleting, etc. Let’s think of visual attention as doing something similar for thought; highlighting (…) some object in (or portion of) the visual field for further mental processing. Levine 2010: 178

|| 17 See Kaplan 1989a: 526. Later in his ‘Afterthoughts’ (1989b) Kaplan abandoned this view in favor of a purely intentional approach, according to which the semantic content of demonstrative expressions is determined by the speaker’s intentions to demonstratively refer to a particular object, appearances no longer playing a significant role in reference-fixing. But as we are here concerned with demonstrative thought I shall not pursue these questions any further, and refer readers to Susanna Siegel’s informative discussion on this matter (Siegel 2002).

16 | Introduction: What is Demonstrative Thought and How to Explain it?

As we can see the idea of visual selection makes a lot of intuitive sense, and constantly appears in the way philosophers talk about the role of perception in explaining demonstrative thought. Implicit in this idea are two very plausible constraints that any theory of singular representation should be able to account for, namely: 1. Individuation: in order to single out a particular object in a visual array, one must be able to spatially discriminate the object from the background and from other objects around it. 2. Maintenance of numerical identity: in order to single out an object in a visual array, one must be able to track its spatiotemporal trajectory so as to maintain its numerical identity through time and motion. So when the perceptualist claims that visual selection is what explains demonstrative thought, what she has in mind is not only a capacity to delineate the boundaries of the object and segregate it against the background by ‘highlighting’ it (the ‘individuation’ constraint), but also a capacity to maintain its numerical identity in time: for as long as this object remains highlighted in experience, it will be perceived as the same object through time and motion. Therefore, from now on every mention of ‘visual selection’ should be understood as encompassing these two abilities: individuation and maintenance of numerical identity. Combining this idea with the methodological principle of nonconceptual basis, we can understand the perceptualist as claiming that both of these constraints can be elucidated at the more primitive level of perception, in terms of perceptual mechanisms that automatically select objects in the world independently of the application of concepts on the part of the subject. This justifies the perceptualist’s claim that the perceptual states underlying demonstrative thoughts already have singular demonstrative contents, which represent the particular objects that have been automatically selected by the perceptual mechanisms in question. With these ideas in mind, we can summarize the perceptualist approach to demonstrative thought in the following way:

Perceptualism about demonstrative thought: an explanation of our capacity to engage in attention-based mental activities with singular demonstrative contents should be given at the more primitive level of perception, in terms of nonconceptual mechanisms of visual selection.

A natural implementation of this approach appeals to what cognitive science tells us about object perception and tracking in order to characterize visual

Conceptualist approaches to demonstrative thought | 17

selection and nonconceptual basis in an empirically adequate manner. As Levine’s quote above makes clear, the idea of visual selection is most naturally interpreted as suggesting the psychological notion of attention: a psychological mechanism that selects objects in the world and make them available for further cognitive processing. But as we shall see in more detail in the next three chapters, there are different ways to account for visual selection, based on different kinds of perceptual mechanisms. In order to account for these different possibilities I propose we distinguish two forms of perceptualism: attention-based models that seek to account for visual selection through the psychological notion of attention, and non-attentional models which appeal to perceptual mechanisms of a different sort. But as long as these theories remain committed to the general ideas of nonconceptual basis and visual selection, we may safely classify them as perceptualist theories of demonstrative thought.

1.5 Conceptualist approaches to demonstrative thought At first sight, it might seem as if perceptualism must be the only game in town. After all, it is difficult to see how we could abandon either one of the two main ideas behind perceptualism, namely, nonconceptual basis and visual selection. Even if there are some divergences as to how visual selection is to be explained (i.e., through attentional or non-attentional mechanisms), it is not clear how we could avoid the idea that ultimately it is perception what explains our capacity to have demonstrative thoughts about objects in our external environment. It seems that as soon as we deny nonconceptual basis and visual selection we are also denying a crucial property of demonstrative thoughts, namely, the relational, nonconceptual character of their reference-fixing mechanisms. But according to a distinguished tradition in philosophy, dating back to the writings of Strawson (1959) and Quine (1960), perceptualism would be taking the most basic and fundamental questions about singular representation for granted, and simply presupposing that the entities that are being selected by perceptual processes are being represented by the subject as particular objects. But according to the conceptualist approach to demonstrative thought, to be in mental states with singular demonstrative contents requires a more sophisticated conceptual understanding of what objects are and how they behave in space and time. For it is precisely this understanding what allows us to attribute singular content to the subject’s mental state, rather than a simpler “featureplacing” content that merely captures the subject’s capacity to perceptually respond to recurrent instances of features.

18 | Introduction: What is Demonstrative Thought and How to Explain it?

The contrast here is between a creature who, when perceptually confronted with a particular apple, is only able to recognize that it is once again in a situation where ‘appleness’ is present in its external environment, versus a creature that is able to grasp that it is faced with a particular apple; an apple that might be numerically identical to an apple encountered in earlier occasions, and that might be encountered and re-identified again in the future. In the first case, the content of the creature’s representational state would be captured in terms of a feature-placing structure like ‘appleness’, or ‘appleness here again’. Particular objects are introduced in the content of mental states only at a second, more sophisticated stage of cognitive development, when a set of background conceptual abilities allow the creature to draw a distinction between numerical and qualitative identity. Only then it would be able to represent not only ‘appleness here again’ but ‘this particular apple.18 Without these background conceptual abilities the creature would not be able to have singular demonstrative thoughts about objects. Although it might be able to engage in attention-based mental activities directed at (what are in fact) objects, these activities would not have singular contents. To be clear on what’s at stake here, conceptualism is not denying that demonstrative thought must “pass through” perception, or that perception has a crucial role to play in explaining how demonstrative thought is possible. It is also not claiming that demonstrative reference to objects is achieved in a satisfactional manner, through a descriptive condition conceptually articulated in the mind of the thinker. Indeed, conceptualism would be more than happy to grant that the demonstrative element that characterizes the content of demonstrative mental states must be elucidated through perception. What it denies, however, is that the singular element is to be elucidated in the same manner. A creature who can only represent apples in terms of recurrent instances of features must also be able to ‘visually select’ the apple among other objects concurrently presented in its experience, but this tells us nothing about the creature’s capacities to represent the apple as an individual object. In other words, what conceptualism is saying is that there is an epistemic dimension implicit in the singular element of demonstrative thoughts, which perceptualism leaves unexplained. Ascriptions of singular content should reflect the subject’s capacity to apprehend her external environment as structured into individual objects, but there is nothing in the perceptual processes and mechanisms posited by the perceptualist that suggest this might be the case. If || 18 See Strawson 1959: 214ff, as well as Bermudez 2003 and Cussins 1992 for informative discussions on the ‘feature-placing’ and the ‘particular-involving’ levels of experience.

Conceptualist approaches to demonstrative thought | 19

all we need to capture is a capacity to segregate and track perceptual elements in a visual array, the appeal to singular content would be explanatorily idle. A simpler content, structured in terms of recurrent instances of co-located and perceptually segregated features would do just fine. So if we want to explain how a subject can engage in mental activities with singular demonstrative contents, the conceptualist claims we need more than perceptual mechanisms of visual selection. There must be something in the subject’s psychological and epistemic capacities that suggest she is able to apprehend her external environment as structured into individual objects, and not just recurrent instances of co-located features. And in order to distinguish objects from instances of features as the representata of our mental states, conceptualism claims we must bring in some more sophisticated conceptual knowledge of what objects are and how they behave. As psychologist Gary Hatfield puts it: I (…) contend that object perception proper is something that needs an explanation built upon our fundamental perceptual capacities and invoking conceptual abilities. The perceptual system segregates volumes for us, and naturally tracks such segregated volumes over short periods of time. These are the beginnings of object perception, but they do not yield the content of a persisting, re-identifiable, continuously spatiotemporally locatable entity. For that, we need conceptual structures that take us beyond episodic perception. Hatfield 2009: 252

The role of the theorist, in this picture, is to specify which conceptual abilities must be in place if one is to apprehend one’s external environment as structured in this manner. These abilities must be brought in in order to supplement more primitive capacities of visual selection, effectively transforming the content of perception into a singular demonstrative content. Singularity in a conceptualist picture comes ‘from above’, so to speak, from background conceptual knowledge of what objects are and how they behave. Without this knowledge, we remain unable to distinguish between a creature who is able to represent particular objects, versus one that is only able to respond to recurrent instances of co-located features. With these ideas in mind, we can understand the conceptualist approach roughly along the following lines: Conceptualism about demonstrative thought: an explanation of our capacity to engage in attention-based mental activities with singular demonstrative contents should be given in terms of two kinds of abilities: perceptual abilities that visually select (what are in fact) objects in the world, and background conceptual abilities that put the subject in mental states with singular contents.

20 | Introduction: What is Demonstrative Thought and How to Explain it?

But once we put things this way, it’s hard to see how a full explanation of demonstrative thought could ever be given in perceptualist terms. If the capacity to apprehend our external environment as structured into individual objects requires one to understand, as Hatfield puts it, that objects are “persisting, reidentifiable, continuously spatiotemporally locatable entities”, it’s difficult to see how low-level mechanisms of visual selection could account for these capacities. It seems that once we accept these terms, a conceptualist theory of demonstrative thought is unavoidable. According to the conceptualist these capacities comes at a price: as we shall see in more detail in chapter five, conceptualist theories tend to require more sophisticated conceptual abilities in order for singular representation to be possible. As a result, we end up with highly intellectualistic theories of demonstrative thought that ties it very closely to our capacity to adopt a more detached and reflective stance towards that which we purport to think about. As Hatfield puts it, [Object perception] isn’t free, but it needn’t be. It is work we can do. Simple, honest, conceptual, recognitional, and classificatory work. The kind of work that our highly articulated spatial and chromatic representations enable us to perform when joined with appropriate conceptual resources. Hatfield 1999: 251

Of course, another possibility would be to simply deny the main supposition behind conceptualism. That is to say, we could simply maintain that there are no such epistemic dimensions to singular content: that insofar as perceptual mechanisms manage to segregate and track perceptual volumes in a visual array, this suffices to ascribe singular contents to the resulting perceptual states, which represent particular objects in the world. And upon being in these perceptual states, we could be in a position to have singular demonstrative thoughts about these objects. As both the demonstrative and the singular element have already been elucidated at the level of perception, the appeal to conceptual abilities is superfluous. Indeed, this is something we can do. But I think that in doing so we miss something important about the very notion of representational content, which the conceptualist draws our attention to. The point is that we assign representational content to mental states in order to capture (among other things) the way the subject of the mental state in question represents the world, i.e., to mark certain psychological and epistemic capacities on the part of the subject. This means that the elements we assign to representational content, as well as the way in which they are combined, should reflect the way the subject grasps the

An alternative proposal (and the road ahead) | 21

structure of its external environment. In this picture, there is a distinctive theoretical role for singular content to play, which is to mark a subject’s capacity to apprehend her external environment as structured into individual objects, and not just instances of co-located (and segregated) features: unique, persisting individuals that have come into existence before the subject’s perceptual encounter with them, and that will continue to exist after the encounter has come to an end. An important part of what it is to explain demonstrative thoughts is also to account for the singular dimension of these thoughts, to elucidate questions like: what is it for our thoughts to track individuals rather than recurrent instances of properties? What cognitive capacities underlie it, and how are they manifested? These are questions that any putative theory of demonstrative thought should be able to answer. And here is where the theoretical notion of singular content is especially useful, as a way of marking the capacity to apprehend one’s external environment as structured into individuals. But of course, acknowledging this epistemic dimension of singular content does not necessarily mean adopting a conceptualist approach to demonstrative thought. One alternative, which would maintain the overall project of explaining object representation at the level of preconceptual cognition, would be to capture this epistemic element with a practical knowledge of objects: a practical sensitivity to what objects are and how they behave, which would dispense with the kind of reflective, theoretical understanding that is characteristic of conceptual knowledge. Developing and advancing such a view will be the main goal of this book.

1.6 An alternative proposal (and the road ahead) It is in the context of the perceptualism/conceptualist controversy that I will introduce a further theoretical alternative, which I call the pragmatic view of demonstrative thought. It purports to be a middle ground between perceptualism and conceptualism, seeking to overcome the explanatory limitations of perceptualism without falling into the intellectualist hold of conceptualism. My suggestion is that we can attain this theoretical middle ground by adopting a pragmatist approach to demonstrative thought, which cuts across the perceptualist/conceptualist dichotomy. In this approach, the capacity to think about particular objects in the world is explained through our practical knowledge of what objects are and how they behave, acquired through repeated patterns of active interactions with objects in the world. This view, I will argue, allows us to capture the singular dimension

22 | Introduction: What is Demonstrative Thought and How to Explain it?

of demonstrative thoughts without having to appeal to more sophisticated forms of conceptual knowledge. This intermediary position should be of interest to philosophers of both perceptualist and conceptualist inclinations: to the former, who insist in accounting for singular representation at the level of preconceptual cognition, and to the latter, who often complain that low-level perceptual processes and mechanisms give us too little in the way of a subject’s psychological and epistemic capacities vis-à-vis individual objects in the world. The pragmatic view shares both of these insights, and purports to do justice to both. But before this view can be properly introduced and defended, we still have a long road ahead, where we need to assess the arguments of both perceptualists and conceptualists in more detail. Here’s then how I propose to structure this book: After having clarified in the present introduction what I take demonstrative thought to be and what it is about these thoughts that we need to explain, in chapter two we will examine the perceptualist approach to demonstrative thought in more detail. I will start by examining more carefully the notions of nonconceptual basis and visual selection, and clarify the sense in which they constrain perceptualist explanations of demonstrative thought. This will serve as basis for introducing the two types of perceptualist theories that shall be examined in this book: attention-based and non-attentional. But as the notion of ‘attention’ is often employed in the psychological literature in more than one sense, in order to avoid equivocation I will also distinguish in that chapter various senses of ‘attention’, and specify which one should be presupposed in the attention-based theories to be examined later. Chapter three will look at three attention-based theories that have been recently proposed in the literature: John Campbell’s (2002), Wayne Wu’s (2011a,b) and James Stazicker’s (2012). After critically engaging with these views, at the end of the chapter I will propose a version of an attention-based perceptualist theory that I find most adequate, which will be close in spirit to James Stazicker’s proposal. In chapter four, however, the underlying perceptual bases of this theory will be called into question, on the grounds that attentional processes presuppose that objects have already been selected and represented at a preattentive level. Therefore, the notion of visual selection must forcefully be explained in terms of pre-attentive mechanisms. After reviewing two candidates for these pre-attentive mechanisms, based on suggestions made by Joseph Levine (2010) and Athanassios Raftopoulos (2009a,b), I will criticize them both on the grounds that they fail to meet some basic constraints on object representation (although they supply us with important insights that should be maintained). In order to overcome these difficulties I will construe a hybrid percep-

An alternative proposal (and the road ahead) | 23

tualist theory, which appeals to both attentional and pre-attentive mechanisms in an account of visual selection. I will then consider a challenge to this theory put forward by Mohan Matthen (2005/2012), which argues that these mechanisms fail to account for an important element of object perception: that objects have egocentric locations for us, i.e., they are perceived as in our hic & nunc, as things we can physically manipulate and act upon. This is something our theory should acknowledge, and which the hybrid theory in question would have problems accommodating. Matthen’s own suggestion is that visual selection should be explained by the automatic assignment of egocentric location by what he calls ‘motion-guiding vision’, which roughly corresponds to processing in the dorsal visual stream. Although I will also criticize this suggestion as inadequate, I will keep Matthen’s insight concerning the role of egocentric location in object perception. This will be incorporated into the theory in terms of a third constraint on object representation, which will supplement the ‘individuation’ and ‘maintenance of numerical identity’ constraints introduced in this introduction. I will call this third constraint (following Evans 1982) ‘spatial significance’, which in Evans’ theory is manifested in the subject’s practical ability to locate the object in her egocentric space. Finally, on the basis of all the material reviewed in chapters two and three while having these three constraints in mind, I will sketch a final perceptualist theory of demonstrative thought, comprising three distinct (but interconnected) elements: (1) pre-attentive processes, (2) attentional selection, and (3) sensorimotor knowledge, which will account for the individuation, maintenance of numerical identity, and spatial significance constraints respectively. Chapter five will introduce the conceptualist challenge to perceptualism, which can be summarized roughly along the following lines: ascriptions of singular content mark the capacity to apprehend one’s external environment as structured into individual objects. This requires us to be able to distinguish individual objects from other suitable candidates for the representata of one’s mental states, such as instances of co-located features. But as this demands an understanding that objects continue to exist in time and space independently of our perceptual encounters with them, low-level perceptual processes and sensorimotor knowledge are incapable of marking this distinction. In their place, I will examine the conceptualist’s suggestion that our capacity for singular representation is supported by our capacity to represent space in a so-called ‘objective’ manner. After raising some difficulties to what an ‘objective’ representation of space might be, I will propose that a less problematic suggestion would be to explain singular representation in terms of our practical knowledge of

24 | Introduction: What is Demonstrative Thought and How to Explain it?

what objects are and how they behave in space and time (the pragmatic view of demonstrative thought). One immediate obstacle to a pragmatist approach along these lines, however, is that according to what I call the orthodox view of practical knowledge, this knowledge is restricted to more primitive forms of sensorimotor knowledge, and thus fares no better than perceptualism when it comes to explaining singular representation. In order to address this difficulty, in chapter six I will propose an alternative theory of practical knowledge, based on what I call ‘the cognitive space’: it is a broader notion of practical knowledge, which develops gradually in order to encompass various forms of knowledge and practical abilities, with various degrees of objectivity. In chapter seven I apply this theory to the particular case of singular object representation, and show how our capacity to apprehend our external environment as structured into individuals could be explained in terms of a practical knowledge of objects. I then present empirical evidence that this conception of practical knowledge may be supported by abstract and flexible object representations in the prefrontal cortex, which arise as a function of our experience and active engagements with objects in the world. The result will be a novel way of looking at singular representation and demonstrative thought, which ties it very closely to our embodied interactions with objects in the world, and which assigns a central role for practical knowledge: I call this the pragmatic view of demonstrative thought.

2 Perceptualist Approaches to Demonstrative Thought 2.1 Perception as natural predication To begin our discussion of perceptualism I will resort to a useful metaphor from A.D. Smith, which is that of perception as ‘natural predication’ (Smith 2002). The metaphor invites us to think of a perception of a red object as having the “cognitive force” of the corresponding demonstrative judgment ‘this is red’, in the sense that perception, similarly to the judgment, “asserts” that a particular object in the perceiver’s external environment has the visual feature ‘red’. But with an important difference: in the case of the judgment we can read off from its conceptual structure how the asserted content is composed of singular and general elements, each making a different contribution to the content. The singular element ‘this’ contributes an object the subject demonstratively refers to, the general element ‘red’ contributes a property she attributes to it, and their mode of combination – captured by the copula ‘is’ of predication – tells us that the judgment is true iff the object picked out by ‘this’ has the property picked out by ‘red’. At the level of perception, however, we do not have the conceptual elements ‘this’, ‘is’ and ‘red’ available to capture the way a perception of a red object is assembled out of both singular and general elements.1 The natural analog of the judgment at the level of perception would be, as Smith puts it, the “occurrence of the perception itself” (Smith 2002: 92).2 So there must be something in perception that functions like ‘natural predication’, that is, a singular referential element responsible for picking out objects, a general element responsible for classifying stimuli into perceptual classes (like ‘red’) and a way to combine them that “asserts” that ‘this’ (perceptually presented) object is the bearer of the visual feature ‘red’.

|| 1 Of course, if you think that perception has conceptual content, as philosophers like McDowell (1994) and Brewer (1999) have suggested, then you would disagree with this claim, and argue that the conceptual elements ‘this’ ‘is’ and red’ are already available at the level of perception. I will not engage with these views here, and simply assume that it is at least possible to characterize what it is for a creature to perceive red objects without ascribing to the creature the concepts required to articulate the judgment ‘this is red’ (see the essays in Gunther 2003 for a useful overview of the debate on the conceptual vs. nonconceptual content of perception). 2 Smith attributes this idea to Romane Clark (1979).

26 | Perceptualist Approaches to Demonstrative Thought

When we come to think of it, it seems plausible to suppose that there is something in perception that functions like natural predication. Just like demonstrative judgments are conceptually articulated in the form of a property being attributed to an object, visual perception intimates visual features to be as in particular objects, and it does not seem to be possible for general elements like ‘red’ to occur in perception except in the form of attributions to the particular objects that bear them. Visual features like ‘red’ are never perceived in abstract, as freely floating in space, but always as inhering in particular objects, bounded by the contours of the objects in which they inhere, contained and limited by the surfaces of their bearers, as moving as their bearers move, and so on. In a similar vein, it doesn’t seem possible to perceive an object ‘neat’, without any properties being attributed to it in perception: to perceive an object is already to perceive it in some manner or another, i.e., as having a certain number of properties. This is a basic fact about the structure of visual experience, and something that gives some initial plausibility to the idea of perception as natural predication. As Burge puts it, Perception must always involve singular application of general abilities. They function fallibly to indicate repeatable types and attribute them to particulars. So a perception – a representational perceptual state instance, or the content of a perceptual state instance – must always involve the context-dependent singular application of (general) perceptual attributives. Burge 2010: 3813

To make this point clearer, take a look at the visual scene in front of your eyes. Supposing you are not indoors facing a blank wall, there will be at least a small variety of colours instantiated in the scene, and perhaps even more than one instance of the same colour. Perhaps (let’s suppose) there is a bit of red in front of you and to the left, and a bit more in the back towards to the right, etc. But these multiples instances of red are surfaces (or parts of surfaces) of particular red things, objects whose surfaces are presented in perception as red. Each instance of red perceived is an instance of a visual feature that is attributed to a particular object. So it seems that visual perceptual experience is always structured into singular and general elements, combined in a way that “asserts” that particular objects have certain visual features. “To perceive,” Smith tells us, “is sensuously to judge, (…) with the sensuous character of acts (of sensing) functioning to provide the particular ascriptions made.” (2002: 92).

|| 3 Matthen 2005 and Clark 2000 also make similar points.

Perception as natural predication | 27

But here one may object: what about cases like seeing ‘blueness’ as one looks up to the sky? Wouldn’t this be a counter example to the claim that every instance of colour perceived in a scene is an instance of a coloured object? Not at all: here I agree with Mohan Matthen when he claims that it would be wrong to say we perceive ‘blueness’ in the sky as a free-floating feature, not inhering in anything in particular – on the contrary, we experience ‘blueness’ as in the sky, as contained, limited, and bounded by the limits of the sky, in a determinate portion of the visual field. The sky is being treated by the visual system as some sort of ‘object’. Admittedly, it is an illusory kind of object, since it doesn’t really have a surface that is blue, but a visual object nonetheless: the bearer of ‘blueness’, that which contains, and limits, a particular instance of ‘blue’ in visual experience (Matthen 2005: 282). Be as it may, it is important to notice that the claim that perception involves a combination of singular and general elements makes no commitments as to the way in which these elements are combined: how we take visual perceptual states to be structured will depend largely on our theory of visual perception. Burge (2010), for instance, claims that singular and general elements in perception are always deployed together and cannot be separated from one another, so that the structure of perceptual content would be captured by a noun phrase like ‘this red cube’.4 Matthen (2005), on the other hand, takes visual perception to be compositionally structured, where singular and general elements may be “peeled off” from one another and separately redeployed in other perceptual representations. This compels us characterize visual states in terms of a predicative structure like ‘this cube is red’.5 This is not a trivial dispute, and bears on the level of generality we take perceptual representations to exhibit and how we expect them to interact with one another. Settling this debate, however, would require further discussion, which is beyond the scope of this book. For now we can remain neutral on how perceptual elements combine with one another to compose the contents of visual perception, and stick to the less controversial claim that no matter how they are combined, a perception of a red object would have the cognitive force of the corresponding demonstrative judgment: it would “assert” that a particular object in the perceiver’s external environment has a certain visual feature. In this respect both Burge’s noun phrases and Matthen’s (and Tacca’s) subject-predicate structures

|| 4 Burge takes the separability of general and singular representational elements as a mark of conceptual thought (as opposed to nonconceptual perceivings). It constitutes what he calls “genuine predication”, which requires conceptual propositional abilities. See Burge 2010: 541. 5 See also Tacca 2010 for a comprehensive defense of this view.

28 | Perceptualist Approaches to Demonstrative Thought

would work equally well, and nothing in the present discussion hangs on making a decision one way or another. To sum up, the idea of perception as natural predication follows very naturally from the structure of visual perceptual experience, as general elements in vision always occur in combination with singular attributions to particulars. This is something that makes the perceptualist case stronger, for it gives some initial plausibility to the claim that there must be something in perception that functions like singular terms function in language, as the element responsible for singling out the particulars to which visual features are attributed. As Burge says, “(this) singular element [in perception] is a perceptual analog of occurrent uses of singular demonstratives in language” (2010: 381). In the same way that demonstratives in language function to select an object in a visual scene so that something can be said of it, this demonstrative-like element at the level of perception would pick out an object so that it could benefit from further processing and become an object of thought. And just as we can maintain the numerical identity of an object in time by keeping our finger pointed at it, the perceptualist claims that something analogous is available at the level of visual perception. This last point is important, and illustrates a further reason as to why the idea of natural predication is useful in our discussion of perceptualism. For when a perceptualist claims that singular elements in perception function like demonstratives in language or thought, we should understand this almost literally, in the sense that there is something in the way particulars are picked out in perception that justifies the analogy with demonstratives. The demonstrative-like element is posited as something that singles out objects in the world ‘directly’, so to speak, without the mediation of other representations, providing the first and most fundamental point of contact between the mind and the external world. This perceptual mechanism is almost literally like a ‘pointing finger’, which can select an object in conceptually unmediated ways just by pointing at it.6 At first it might be thought that this is a rather trivial claim, given that we have already granted that an important property of demonstrative thoughts is that their objects are determined relationally, via perception, rather than through concepts in the mind of the thinker. But the problem here is of a slightly different nature: when thought or language is concerned, saying that the intentional object of a demonstrative thought is determined via perception already suffices to

|| 6 The analogy between pointing fingers and perceptual reference-fixing mechanisms has been explored at length in Pylyshyn’s FINST model of visual reference (2001/2007). This model will be discussed in chapter four.

Direct and indirect reference-fixing mechanisms | 29

distinguish it from descriptive thoughts (whose object is determined satisfactionally by concepts). But when we move to the level of perception we are faced with another version of the same problem. For once we assign the theoretical burden of reference-fixing to some process or mechanism in the visual system, we must be able to show that this process or mechanism is something that picks out external objects, rather than further perceptual representations. This is what it means for a reference-fixing mechanism to be ‘direct’, in the context of the present discussion.7

2.2 Direct and indirect reference-fixing mechanisms To have a clearer idea of the problem, suppose we say, as Campbell once suggested, that the most basic and fundamental problem of demonstrative thought is to elucidate how propositional content relates to imagistic content (Campbell 1997: 55). In this picture, what the theorist must explain is how the singular expression ‘this’ – which figures in propositional inference and thought – can select an individual element in an iconic representation of a visual scene, given that conceptual and imagistic content have different structural properties. We certainly could come up with such a story, but in the end we would only have managed to connect one kind of representational content with another. That is to say, even if we manage to explain how the demonstrative ‘this’ in thought manages to pick out an individual element in an iconic perceptual representation, an important question would remain unanswered: how, in turn, does imagistic content connect to particular objects in the world? If we do not want the same problem to arise at each successive level of analysis, at some point there must be in perception a purely ‘demonstrative’ way of picking things out in the world, that does not appeal to other kinds of perceptual representational content. In order to accommodate these observations, we need to make an important qualification to the definition of perceptualism put forward in our introductory chapter. I have then defined perceptualism in terms of a commitment to the following claim:

Perceptualism about demonstrative thought: an explanation of our capacity to engage in attention-based mental activities with singular demonstrative contents should be given at the more primitive level of perception, in terms of nonconceptual mechanisms of visual selection.

|| 7 This notion of ‘directness’ will be qualified in chapter four (section 4.1.1), but we can stick to this preliminary definition for now.

30 | Perceptualist Approaches to Demonstrative Thought

This constrains the nature of the explanation, as it requires it to be wholly construed at the more primitive level of perception. But as the considerations above make clear, this is not enough to explain how perception connects demonstrative thoughts to external objects in the world. Taking on board our observations on the ‘direct’ character of the demonstrative-like element in perception, we can now add the following qualification to our definition of perceptualism:

Perceptualism about demonstrative thought: an explanation of our capacity to engage in attention-based mental activities with singular demonstrative contents should be given at the more primitive level of perception, in terms of nonconceptual, direct mechanisms of visual selection.

Of course, this definition still leaves open what kind of perceptual mechanisms these could be, although it imposes specific conditions something must meet in order to play this role. Whatever it is that we posit, it must conform to perceptualism’s theoretical constraints and methodological guidelines. One candidate that naturally comes to mind is the psychological notion of attention. Indeed, when I have introduced the idea of visual selection in the previous chapter through the metaphors of “highlighting” a portion of the visual field or having a “little arrow” in perception pointing at the relevant object, both of these metaphors are strongly suggestive of attentional mechanisms of visual selection. By focusing our attention on ‘this object’ rather than ‘that one’, the object becomes “marked”, “highlighted”, visually selected in a scene among other concurrently presented objects. So at least on an intuitive level, attention seems to be crucially involved in how perception selects objects in the world, which puts us in a position to have demonstrative thoughts about them. Therefore, it makes sense to start our discussion of perceptualism with attention-based models of demonstrative thought, and then move on to non-attentional models. If we remember a schema introduced in the previous chapter (and replicated below for ease of exposition), an attention-based perceptualist would be someone who takes R’ to be an attentional relation, something that explains how the underlying perceptual state P is connected to external objects. By securing an object on the basis of R’, P puts the subject in a position to have demonstrative thoughts (M) about the attended object. In this picture, M would inherit the singular content of the underlying perceptual state P, determined by the attentional relation R’. Following the basic constraints of perceptualism, this is a nonconceptual reference-fixing mechanism, which can be explicated without appealing to concepts in the mind of the thinker.

Attention-based perceptualism | 31

Fig. 1: Simple relation between demonstrative mental states and perceptual states

2.3 Attention-based perceptualism When we come to think of it, it is difficult to see how a perceptualist theory of demonstrative thought could not be “attention-based”. After all, we’ve already seen in the previous chapter that an important property of demonstrative mental states is, precisely, that they are attention-based states, so the appeal to the psychological notion of attention in an account of demonstrative thought seems unavoidable. But if this is true, then the whole idea of distinguishing attentionbased from non-attentional models might seem trivial: shouldn’t it be obvious that any putative theory of demonstrative thought must be based on attention anyway? But here we must be careful to distinguish the claim that demonstrative thought (somehow) involves attention, from the claim that attention is the perceptual relation R’ in the schema above. No one (I hope) would dispute that there is a very tight connection between the psychological notion of attention and the philosophical notion of demonstrative thought, but the claim under consideration is of a different nature: what attention-based theories claim is not only that demonstrative mental states involve the allocation of attention, but that attention plays a very specific explanatory role in relation to demonstrative thought. In accordance with the definition of perceptualism put forward in section 2.1, we may then say that an attention-based perceptualist is someone who is committed to the following claim:

32 | Perceptualist Approaches to Demonstrative Thought

Attention as visual selection: attention explains demonstrative thought in virtue of being a direct mechanism of visual selection, fully characterized in perceptual terms.

This claim is stronger and more controversial than the non-committal claim that demonstrative thought (somehow) involves attention, or that demonstrative mental states are attention-based states. For suppose one denies ‘attention as visual selection’: this would still allow one to be a perceptualist, as long as one remained committed to the claim that there is some other (non-attentional) mechanism of visual selection that can bear this theoretical burden. Further on, denying this claim does not mean severing the connections between attention and demonstrative thought. One could, for example, take attention to be a cognitive phenomenon, which arises when one deploys resources of higher cognition to an object of visual perception. In this picture, attention would no longer be the underlying perceptual relation R’ that connects thought to external objects, although it would still bear a very tight relation to demonstrative thought. In fact, both would be simultaneous effects of a common cause: namely, the selection of an object in the world through some non-attentional perceptual mechanism. The main difference between these two positions is illustrated below:

Fig. 2: Different ways in which attention could be related to demonstrative thought: an ‘attention-based model’ as I have defined it is illustrated on the left side.

In short, what distinguishes an attention-based perceptualist theory is not its appeal to attention in some way or another, but a commitment to the thesis of ‘attention as visual selection’. As we’ve seen, denying the truth of this thesis is still compatible with attention playing an important role in a theory of demonstrative

Attention-based perceptualism | 33

thought. Depending on how we interpret the elements in the figure above and how we take them to be related to one another, the right-hand side of the figure could be modified in some interesting ways in order to accommodate different interpretations of attention and demonstrative thought. Perhaps one could say, for example, that demonstrative thought is nothing but a form of cognitive attention to objects, in which case one would merge the attentional state and the demonstrative mental state into one single notion of ‘cognitive attention’, connected to the external object by non-attentional mechanisms of visual selection. Or perhaps one would want to keep the two notions distinct, and take demonstrative thought to be a further type of focalization on an object of visual perception, that exploits mechanisms of attention while still being distinct from it. If this is one’s view, then one could move the demonstrative mental state to a higher position above the attentional perceptual state, two levels removed from the initial non-attentional state at the bottom.8 No doubt there are other ways to construe the relation between these elements, with interesting philosophical consequences to follow from each construction. But in putting forward attention-based perceptualism in this chapter, I am concerned only with a very specific claim about the relation between attention and demonstrative thought: namely, whether ‘attention as visual selection’ is true. Or, to put in slightly different terms, whether the left-hand side of the figure above paints an adequate picture of how perception puts us in a position to have demonstrative thoughts about external objects. An affirmative answer would make one an attention-based perceptualist, while a negative answer would lead to a non-attentional theory of visual selection. What other roles attention could play in the theory is a further question, that might be posed once we decide on the truth of ‘attention as visual selection’. This was the first clarification needed in our discussion of attention-based perceptualism. But we must also be careful to specify which notion of attention is presupposed in the theory. After all, even a brief survey of the psychological literature on attention will reveal that there is an enormous variety of psychological phenomena studied under the guise of ‘attention’, and, further on, it’s unlikely that there is a single set of neurophysiological mechanisms that realise these phenomena.9 So if the attention-based perceptualist wants to substantiate her claim, she must be more precise about which notion of attention is at stake, so that we can properly understand the claim that attention is what explains our capacity to engage in mental activities with singular demonstrative contents. || 8 Some of these possibilities will be explored in chapters three and four. 9 On this last point see Allport 1989.

34 | Perceptualist Approaches to Demonstrative Thought

The problem may be put in the following terms: there is on the one hand a very intuitive notion of attention, that is familiar from introspection and manifested in an ordinary understanding of the term. This is the notion that is at play in metaphors like “highlighting” a portion of the visual field with a yellow marker or “marking” the attended object with a little arrow. This intuitive notion corresponds to William James’ famous and widely quoted characterization of attention, which we may repeat here for ease of exposition: Every one knows what attention is. It is the taking possession by the mind, in clear and vivid form, of one out of what seem several simultaneously possible objects or trains of thought. Focalization, concentration, of consciousness are of its essence. It implies withdrawal from some things in order to deal effectively with others. James 1890/1981: 403, quoted in Wu 2011a: 93

This view characterizes attention as a conscious phenomenon under volitional control, that can be directed at will to different portions of the visual scene and which has a distinctive phenomenological effect: upon the allocation of attention the object will be experienced in “clear and vivid form”, as “highlighted” or “marked” in experience, as phenomenally more salient relative to other unattended objects concurrently presented in the scene. This is a very intuitive and compelling understanding of attention and its effects on conscious experience (one that “everyone knows”), which seems to capture an important aspect of our conscious lives. But although there may have been a time when the word ‘attention’ could be used in a theoretical context without qualification, and the reader would be licensed to assume the intuitive Jamesian reading, this is no longer true. For many selective phenomena now studied in empirical perceptual psychology under the guise of ‘attention’ do not exhibit the signature marks of Jamesian attention; namely, being conscious, under volitional control, and having a distinctive phenomenal character. Robert Kentridge and collaborators, for example, have provided compelling evidence for attentional selection without awareness in blindsight patients: when they pre-cued the spatial location where visual stimuli would subsequently appear, they found a significant improvement on patients’ performances in detection tasks, even if these patients remained unaware of the stimuli and the pre-cues.10 If, as the authors argue, this behavioural effect is to be explained by attentional mechanisms, the notion of attention at play is clearly very different from the intuitive Jamesian notion that “everyone knows”. || 10 Kentridge et al. 1999/2004/2008. These experiments will be discussed in more detail in chapter 3.

Attention-based perceptualism | 35

And there are good reasons to take these mechanisms to be attentional in nature. For starters, these experiments employ Posner’s classic spatial pre-cueing paradigm (1980), which is widely used and accepted as a reliable and effective method to test the effects of attention. So if we accept, in the normal conscious cases, that faster and more accurate detection upon spatial pre-cueing is due to the beneficial effects of selective attention, we should also accept the same explanation in the blindsight case. Both cases involve the same behavioural effects, and exploit the same neural mechanisms of spatial attention. As the authors put it: Although [the blindseer’s] lesion affects his vision, it is unlikely to affect parietal and other neural representations of space which play a vital role in spatial selective attention—the spatial map in which attention is allocated remains intact. Kentridge et al. 2004: 834

So it seems that being a conscious phenomenon under volitional control with a distinctive phenomenology are not essential properties of attention. Indeed, neuroscientist Victor Lamme claims that attention and conscious awareness are two very different psychological phenomena, and that it would be a mistake to conflate the two. Attention according to Lamme is a scientific and theoretical notion, to be discovered by the empirical sciences and explained in terms of neural mechanisms that select a subset of stimuli for faster and deeper processing, so that they have a better chance of producing or influencing a behavioural response. Explaining these mechanisms do not require us to appeal to conscious awareness or phenomenological effects of any kind. As Lamme puts it: The combination of sensory processing (including internal milieu variables) with short- and long-term memory explains why a particular brain at a particular moment in time is inclined to favour one stimulus over another. We can even imagine this to occur in brains (or machines for that matter) without any phenomenal experience. Therefore, attention is not a priori associated with awareness. Lamme 2003: 15

In this picture, the Jamesian view would be guilty of taking features of a special case of attention – one where there happens to be conscious awareness involved – and generalizing it to the whole psychological kind. And the problem with this generalization is that it cannot distinguish properties of phenomenal awareness from properties of attention, as both are introspectively indistinguishable. But as they belong to different psychological kinds, the resulting description – the everyday notion of attention, accessible by introspection – would not be theoretically well defined.

36 | Perceptualist Approaches to Demonstrative Thought

On the basis of these difficulties, some philosophers have proposed that the intuitive notion should be reduced to the scientific notion, or perhaps even eliminated altogether from psychological theorizing; other philosophers, however, claim a place for the intuitive notion as an adequate phenomenological characterization, which is (somehow) related to the scientific notion without being coextensive with it.11 Settling this debate would require further discussion that is well beyond the scope of this book, but for present purposes we need not make a decision one way or another. We can remain neutral on the legitimacy of the intuitive notion or its relation to the scientific notion, as long as we are careful to specify which of these notions is at stake in the perceptualist theories to be examined in this book. What we can say is this: on the one hand, there is the Jamesian notion of attention that “everyone knows” – an aspect of our conscious lives under volitional control that brings with it distinctive phenomenological effects. The allocation of attention brings an object into focus, making it phenomenally more salient relative to other unattended objects around it. Whenever this notion of attention is employed it will be qualified as ‘conscious attention’, and the reader should have in mind the Jamesian notion with all its signature marks – consciousness, volitional control, and distinctive phenomenological profile. On the other hand there is the scientific notion of attention, one that is not available in introspection and whose understanding requires us to deploy the most advanced methods of the empirical sciences. This notion of attention refers to neural mechanisms responsible for selecting a subset of stimuli for faster and deeper processing. When this notion of attention is at stake I will use the more general term ‘selective attention’. At first this may be a little confusing, since selective attention is often employed in the literature in the sense of conscious selective attention. But I find this terminology useful to highlight the fact that we are dealing here with selective brain mechanisms, which select certain stimuli for faster and deeper processing regardless of the signature marks of Jamesian conscious attention. Whenever the reader comes across ‘selective attention’ in the course of this book, the scientific notion should be kept in mind. And if no qualification is made, it’s because nothing will hang on this distinction. This gives us to distinct paths an attention-based perceptualist could take in an explanation of demonstrative thought: on the one hand, she could argue that

|| 11 See Watzl 2011 for an excellent overview of how these different possibilities could be developed and defended.

Attention-based perceptualism | 37

what makes ‘attention as visual selection’ true is conscious attention, i.e., a conscious mechanism of selection under volitional control and with a distinctive phenomenological profile, that selects objects in the world in a direct manner and that may be wholly characterized in perceptual terms. But on the other hand, she may also claim that what makes ‘attention as visual selection’ true is selective attention, understood in a theoretical sense as the process, or set of processes, responsible for selecting visual stimuli in a visual scene for faster and deeper processing, and where the signature marks of Jamesian attention would play no relevant explanatory role. In chapter three I will explore both of these possibilities. I’ll start by examining John Campbell’s claim that conscious attention explains demonstrative thought precisely in virtue of its distinctive phenomenology, whereby a particular object is experienced as highlighted, as phenomenally more salient relative to other unattended objects around it (2002). Campbell’s strategy consists in arguing, on the basis of empirical evidence, that conscious attention picks out objects in the world directly, and puts the perceiver in perceptual states characterized by the phenomenology of conscious attention. This phenomenology, Campbell claims, may be fully explained by facts about where the subject directs her attention (i.e., which objects are attentively singled out). This explains how demonstrative thought about external objects is possible. In the absence of this phenomenal property, Campbell claims that perceptual states could not adequately ground demonstrative thoughts about objects. This claim will be criticized by Wayne Wu (2011a), who argues that the phenomenal character of conscious attention is nothing other than the phenomenology of demonstrative thought: therefore, it cannot be what explains it. His proposal appeals to a theoretical notion of selective attention he calls ‘attention as selection for action’ (2008/2011b), which he borrows from Alan Allport (1989): an attentional mechanism responsible for selecting a subset of perceptual input in order to drive the appropriate motor outputs, whose operation does not presuppose any of the signature marks of Jamesian conscious attention. Finally, James Stazicker (2012) will be presented as a sort of middle ground between Campbell and Wu. For although Stazicker also appeals to conscious attention in order to construe his theory, he disagrees with Campbell that conscious attention explains demonstrative thought in virtue of its distinctive phenomenology. Rather, particular acts of conscious attention account for visual selection insofar as they set some subpersonal perceptual mechanisms into play that will directly pick out objects in the world. But these acts of conscious attention will have two simultaneous effects – the phenomenal salience of the attended object and

38 | Perceptualist Approaches to Demonstrative Thought

demonstrative thought – so it is only normal that the phenomenology of attention-based states should be inseparable from the phenomenology of demonstrative thought. But as what bears the theoretical burden here is not the phenomenal character of conscious attention, Wu’s phenomenological objections against conscious attention are no longer effective.

2.4 Non-attentional perceptualism Other philosophers, however, deny the truth of ‘attention as visual selection’, and are sceptical about the prospects of explaining object selection through attentional mechanisms of any sort. One reason that ‘attention as object selection’ cannot be true, according to Joseph Levine (2010), is that current empirical evidence supports the existence of pre-attentive perceptual representations of objects, which function as the units of visual attention. Attention is then said to operate on these pre-attentive representations, rather than picking out objects in the world directly. In order to argue for this claim Levine appeals to Pylyshyn’s work on visual indices (2001/2007), where the first point of contact between the mind and the external world is explained in terms of pre-attentive mechanisms of index assignment in the early vision system. This indexing mechanism picks out objects in the world on a purely causal basis, guided by operational constraints built into our visual system by evolutionary pressures. Attention in this picture (be it conscious or selective) is a further mental operation that takes visual indices as its operand, thus falsifying ‘attention as visual selection’. In a similar vein, Athanassios Raftopoulos (2009a,b) appeals to empirical data from fMRI studies and electrophysiological recordings to argue that the time-scales of visual processing do not support an attention-based model of object selection. Based on the work of Victor Lamme and collaborators, Raftopoulos distinguishes between three stages of visual processing: the feedforward sweep (FFS), local recurrent processing (LRP), and global recurrent processing (GRP). These stages are defined and distinguished from one another in terms of latencies of visual responses. The FFS starts at about 40ms after stimulus onset when the first patterns of activation are registered in V1, and lasts until 100-120ms with the activation of most visual areas in the visual cortex. Neuronal activity at this stage, as its name indicates, only moves forward in the hierarchy of visual areas, never sideways or backwards.12

|| 12 Lamme 2003, Lamme & Roelfsema 2000.

Non-attentional perceptualism | 39

The first signs of recurrent processing are registered at about 100-150ms, as horizontal and feedback connections are established in the same areas that were activated during the initial FFS. This is the level of local recurrent processing (LRP), which marks recurrent processing that is local to visual areas and that does not benefit from the modulatory effects of attention. Raftopoulos then presents evidence that at about 100 ms after stimulus onset – so still during the pre-attentive FFS and LRP – there is already in the early vision system a structured representation of the scene, where object-centred segmentation processes deliver multiple representation of objects even before index assignment takes place (Raftopoulos 2009a: 354). In contrast, the effects of attention on perceptual processing are only registered at about 200 ms, at the level of global recurrent processing. What this means is that attention influences visual processing by recurrently affecting the very same areas activated during the FFS and LRP, enhancing activation of neuronal assemblies representing attended objects or locations. This suggests that attention is a mechanism that enhances perceptual representations of objects, rather than selecting objects in the world in the first place. Therefore, ‘attention as visual selection’ is false. What explain visual selection, according to Raftopoulos, are object-centered segmentation processes responsible for parsing the initial visual input into discrete perceptual elements (Raftopoulos 2009a: 354). Although Levine and Raftopoulos disagree on which perceptual mechanism explains object selection, they both appeal to pre-attentive object representations in the explanation of demonstrative thought. So they are both committed to the claim that visual perception selects objects in the world by (pre-attentively) representing them in the early vision system, something that puts the perceiver in a position to direct her attention to these objects and to think demonstratively about them. But this is not the only option available to a non-attentional perceptualist. An alternative view, suggested by Mohan Matthen (2005/2012), is to say that visual perception puts us in a position to attend to objects and to have demonstrative thoughts about them through a mechanism called ‘motion-guiding vision’, which is responsible for locating objects in space in agent-centred coordinates. As Matthen puts it, Vision singles out its object by furnishing the perceiver with an egocentric location for that object. The location is not provided “explicitly” – that is, seeing something does not enable

40 | Perceptualist Approaches to Demonstrative Thought

a perceiver to say where things are relative to her. Rather, seeing something enables a perceiver to attend to the thing and orient herself relative to it. Matthen 2012: 2213

In order to motivate this view, Matthen appeals to a well-known and well-established fact in perceptual psychology, which is that the mechanisms that control and guide motor actions on visible objects are distinct from the mechanisms that provide us with conscious awareness of objects’ features (like colour, shape, motion, and so on).14 Matthen’s thesis is that the former mechanisms are what explain how visual perception puts us in a direct contact with external objects, by putting us in a position to physically manipulate them and providing us with a feeling of perceptual presence. This is what he calls ‘motion-guiding vision’, roughly corresponding to processing in the dorsal visual stream: the mechanism responsible for assigning objects a spatial position in agent-centred coordinates, which is the kind of information the visuomotor system needs in order to properly guide and control action. Motion-guiding vision is not an attentional mechanism. On the contrary, it is what explains how attention is possible in the first place, by providing the egocentric spatial coordinates the visuomotor system needs in order to guide the allocation of attention to a specific location in the visual field. In this sense, it is still a pre-attentive mechanism, albeit one that is very different from the mechanisms Levine and Raftopoulos appeal to. For while object-centred segmentation processes convey information about object’s shapes and sizes, and visual indices are assigned to objects that have been segregated in this process, motion-guiding vision locates objects in space while conveying no information whatsoever about them (other than their location). This mechanism is supposed to be a purely deictic device that points to a particular location in space occupied by an object without conveying any information about what is there other than agent-relative location (2005: 302).

|| 13 Page numbers refer to the electronic version of the paper found in the author’s website: http://individual.utoronto.ca/matthen/Site/Mohan_Matthen_files/VISUAL%20DEMONSTRATIVES%20final%20version.docx 14 Ungerleider & Mishkin 1982, Milner & Goodale 1995.

Final remarks | 41

2.5 Final remarks The aim of this chapter was to provide the reader with a more elaborate picture of what perceptualism about demonstrative thought amounts to. The perceptualist position is now clearly defined as the claim that an explanation of demonstrative thought should be given at the more primitive level of perception, in terms of demonstrative-like mechanisms that individuate and maintain the numerical identity of objects in the world in a nonconceptual and direct manner. In addition, I have also explored different ways in which a perceptualist theory could be developed, depending on the nature of the perceptual mechanisms posited: ‘attention-based’ or ‘non-attentional’. But as our brief excursion into these theories has shown, there are multiple notions of attention as well as different features of attention that could explain visual selection. This introduces some complications in the logical space to be explored in the course of this dissertation, and the picture we now end up with is the following:

Fig. 3: Possible perceptualist theories of demonstrative thought

These possibilities will be explored in greater detail in chapters three (attentionbased theories) and four (non-attentional). Once we have covered this ground we will be in a better position to assess the theoretical adequacy of perceptualism, as we will have in hands a wide variety of theoretical tools and empirical evidence we can appeal to in construing a satisfactory theory of demonstrative thought

42 | Perceptualist Approaches to Demonstrative Thought

under the perceptualist constraints. This will be particularly useful when I introduce the conceptualist challenge to perceptualism in chapter five, for at this point it should be quite clear what the theoretical limitations of perceptualism are.

Attention-based Perceptualist Theories of Demonstrative Thought .

John Campbell

. .

Experiential highlighting

In John Campbell’s attention-based perceptualism, conscious attention is what explains our capacity to have demonstrative thoughts about objects. More specifically, conscious attention plays this theoretical role in virtue of putting the subject in conscious perceptual states with a distinctive phenomenal property, whereby the attended object is perceived as phenomenally more salient relative to other unattended objects. Campbell calls this phenomenal property of attention-based perceptual states ‘experiential highlighting’, and it is only in virtue of having this property that perceptual states can adequately explain demonstrative thoughts about objects. Campbell first introduces this notion in terms of the metaphor of highlighting a portion of the visual field with a yellow marker Campbell : , which seeks to capture the distinctive phenomenology of Jamesian conscious attention discussed in chapter two. When a subject is presented with objects x and y but consciously attends to x, this act of conscious attention brings x into focus, at the same time that y is assigned to the background; x is then highlighted in her conscious experience of the scene, to the detriment of y. But if the subject then consciously shifts her attention to y, the reverse occurs, and y will be highlighted in her experience to the detriment of x. To make matters clearer, try it out for yourself: stare inattentively and distractedly at the landscape in front of your eyes, then consciously focus your attention on a particular object in the scene, disengage attention, shift it to another object, and so on. With each conscious shift of attention you will undoubtedly appreciate the way in which your experience is changed. The attended object now stands out among the others, you are able to see more of its details, its shape and contours become better defined, at the same time that unattended objects in the scene start to fuse into a more-or-less undifferentiated background. It does feel, in a way, as if you are highlighting the attended object with a marker , accentuating its appearance, making it phenomenally more salient. This is something you can do through the conscious allocation of atten See Campbell

: ch. for further details.

 Attention-based Perceptualist Theories of Demonstrative Thought

tion. So when an object is perceived in this manner we shall say it is experientially highlighted, and the perceptual state one is in upon consciously attending to the object will have the property of experiential highlighting. To be clear, what is being emphasized here is not so much a matter of quality or quantity of information one is able to acquire through the conscious allocation of attention to an object or portion of the visual field. In this sense, the example above might be a bit misleading, for it exploits a case where the allocation of attention makes the object be experienced in high detail, with welldefined contours, bright colours, etc. But we should also grant that an object may be experientially highlighted even in circumstances where you are not in a position to have a lot of or good information from it – for example, if the object is seen at a distance or under poor conditions of illumination. But as long as you are able to select, through conscious attention, just that object rather than another, this object will be experientially highlighted for you. So the relevant notion of experiential highlighting should not be understood in absolute terms, i.e., as high quality or quantity of information made available by conscious attention, but always in relative terms: the attended object, or portion of the visual field, is experienced as phenomenally more salient relative to other, unattended objects and/or portions of the visual field. It is essentially an element of contrast. But why should we believe that it is only in virtue of having this phenomenal property that attention-based perceptual states can explain how demonstrative thought is possible? Couldn’t we do without this specific property? One way to argue for Campbell’s claim would be to find cases where we remove the property of experiential highlighting from the perceptual state while leaving attention intact. If the removal of experiential highlighting also removes the capacity for demonstrative thought, this would support the claim that not only attention but also experiential highlighting are required for demonstrative thought to take place. An experiment seen in chapter involving attention without conscious awareness in blindsight patients would make a good case. To briefly review the experiment, Robert Kentridge and collaborators have found that pre-cueing the location where stimuli will appear in a patient’s blind hemifield makes detection of stimuli faster in that location, even if patients do not consciously experience the stimuli or the cues . In the experiment illustrated in figure below, patient G.Y. was initially presented with a central fixation cross frame , which

 See Campbell

: for an explicit endorsement of this point.

John Campbell 

was then briefly followed by a spatial cue illustrated by the two horizontal bars in the frame . Shortly after an auditory note would signal the beginning of the target phase bottom frames , prompting G.Y. to indicate whether a target was presented in the display or not each frame was present in the display for an average of . seconds . After making his response, G.Y. was further asked to comment on whether he had consciously experienced the target or not.

)ig. : Experimental design for attention without awareness in blindsight from Kentridge et al. 999

What Kentridge et al. have found was that valid cues bottom-left frame, where cue and target have matching locations elicited significantly faster responses to targets than invalid cues bottom middle frame ; conversely, invalid cues elicited slower responses than neutral control conditions. In addition, G.Y. did not report conscious experience of the targets or the pre-cues, for that matter in any of the trials he was submitted to. Based on these results, the authors conclude: These findings confirm the observation that topographic information is processed in the blind hemifield and is available to a variety of neural mechanisms controlling responses such as eye movements … and verbal responses … . The present results provide compelling evidence that topographic information is also available to mechanisms which allow G.Y. to direct attention to locations in his blind field selectively. Kentridge et al. :

 Kentridge et al.

:

.

 Attention-based Perceptualist Theories of Demonstrative Thought

These experiments provide compelling evidence that we can have the effects of attention at the neural and behavioural levels without a corresponding effect in conscious experience. But quite plausibly, when we take away the conscious experience of the object we also take away the capacity to have demonstrative thoughts about it. To see why, just consider what things are like for this patient. G.Y. repeatedly denies having any conscious experiences of the targets or cues, and suspects there might not be anything at all in the visual display. He is quoted as telling the experimenters things like I would be none the wiser if you were not putting any cues up, just to confuse me , and as insisting that all he was doing throughout the experiment was listening to the beep [the auditory cue that prompted the beginning of the target phase] and pressing a button . In the absence of the relevant conscious experiences, G.Y. is simply not in a position to think ‘that one’ of one of the targets in the display. Perhaps after a large number of trials G.Y could become convinced he was being presented with targets and cues in his blind hemifield after all, and come to have thoughts about these targets. But they would be descriptive thoughts of the form ‘the target in my blind hemifield causally responsible for these behavioural responses’ or something along these lines, and would not have the directness of demonstrative thoughts, which refer to objects without conceptual intermediaries. As 0aomi Eilan correctly points out , there is a direct explanatory link between the appeal to descriptive material in characterizing the content of the patient’s thoughts, and the absence of conscious experience of the stimulus. Without the latter, G.Y. is not in a position to have demonstrative thoughts about visual stimuli presented in his blind hemi-field. So it seems that the role of attention in explaining demonstrative thought cannot be restricted to the neural and behavioural effects of attention, but must include its phenomenal effects as well: namely, the experience of an object as experientially highlighted. As Campbell puts it, The attention that is needed here is, as it were, a matter of experiential highlighting of the object; it is not enough merely that there be some shifts in the architecture of my information-processing system, remote from consciousness. To understand how knowledge of reference depends on attention we will have to understand the relation between the expe-

 Ibid. Knowledge of reference is what Campbell believes experiential highlighting can give us, but I will be neutral on whether we should call this knowledge or not. As I have explicitly said in the introductory chapter, we can understand the relation between perception and demonstrative thought in terms of the former putting one in a position to do the latter, but

John Campbell 



riential highlighting of an object and underlying shifts in the configuration of information processing machinery. Campbell :

But here an objection could be raised. Let’s grant, based on the considerations above, that in order to think demonstratively of an object one needs to have conscious visual experiences of this object. This is precisely what the blindseers lack, which explains their incapacity to have demonstrative thoughts. But granting this point does not establish that the relevant conscious perceptions need to be perceptions of the object as experientially highlighted. According to the objection, we could fully explain demonstrative thought by appealing to conscious perceptual states with visual phenomenology, causally connected to the external objects they concern. Experiential highlighting does not seem to add anything to this explanation. One way to answer this objection is through an example seen before, involving a contrast between two kinds of experience. The first is the sea of buildings experience, as the experience one may have as one gazes distractedly out of one’s window into the urban landscape below without visually selecting any particular building in the scene. The second is the experience of a building as experientially highlighted, which occurs when one consciously allocates attention to a particular building in the scene. In both cases there is conscious perception of objects with visual phenomenology causally connected to external objects, but only the second experience puts one in a position to have demonstrative thoughts about a particular building. Therefore, it is simply not true that experiential highlighting does not add anything to an explanation of demonstrative thought. The kind of phenomenology of conscious perception that we need if we want to explain how demonstrative thought is possible is precisely the phenomenology of experiential highlighting: for it is this phenomenal property what allows us to distinguish conscious experiences that do not give rise to demonstrative thoughts the sea of buildings experience from those that do. But there’s another – and perhaps more serious – objection that could be raised to the explanatory role of experiential highlighting. According to this objection, the sea of buildings example only establishes that experiential highlighting reliably correlates with demonstrative thoughts about objects; whenever the former is present, the latter is also present; remove the former,

 whether perception does so by providing one with knowledge of the referent is not important for present purposes.

 Attention-based Perceptualist Theories of Demonstrative Thought

and the latter is also removed; and so on. But this correlation is compatible with a suggestion briefly considered in chapter two, according to which conscious attention with its associated phenomenology does not support demonstrative thought but arises simultaneously to it, as two effects of a common cause – namely, some form of visual selection other than conscious attention. In this picture, it would not be strictly speaking correct to say that in the sea of buildings example there is no demonstrative thought because there is no experiential highlighting. Rather, there is neither demonstrative thought nor experiential highlighting because there is no visual selection of a particular building in the first place. So the sea of buildings example does not really establish that experiential highlighting is what explains how demonstrative thought is possible. So it seems that the considerations Campbell appeals to are insufficient to distinguish between two competing accounts of the same phenomenon. If we want to maintain, as Campbell suggests, that experiential highlighting is something more primitive than demonstrative thought, something we can appeal to in explaining how the latter is possible, we need to bring in further considerations that would allow us to decide the issue on Campbell’s behalf. We would need, in other words, to argue for the truth of the following pair of claims: . Conscious attention is a form of visual selection of objects, something that makes objects available to be perceived in the first place. . The distinctive phenomenology of conscious attention ‘experiential highlighting’ arises at a level of experience that is more primitive than thought about objects, and is fully explainable in terms of facts about where the subject consciously directs his attention with no appeal to higher cognitive states . The truth of these two claims would invalidate the objection, as it would rule out the possibility of experiential highlighting being a cognitive element of experience arising at the same level as demonstrative thought, which would presuppose a prior selection of an object of perception. These two claims would establish experiential highlighting as a purely perceptual phenomenon, that takes place as conscious attention roams over the visual scene and visually selects various objects in the world to be experienced by the subject. This is exactly the view Campbell wants to argue for when he compares conscious attention to the Russellian notion of ‘acquaintance’: Russell thought of acquaintance as a cognitive relation more primitive than thought about an object, which nonetheless, by reaching all the way to the object, made thought about the object possible. … This provides a model for the way in which we think of conscious attention to an object. It is a state more primitive than thought about the object, which

John Campbell 

nonetheless, by bringing the object itself into the subjective life of the thinker, makes it possible to think about that object. Campbell :

In this quote we can clearly see how Campbell’s theory fits very well with perceptualism about demonstrative thought, and, more specifically, how Campbell is committed to the claim early characterized as ‘attention as visual selection’. The analogy with Russellian acquaintance emphasizes that Campbell is thinking of conscious attention here as a direct mechanism of visual selection, that picks out objects in the world without representational intermediaries, and which is explainable at the more primitive level of perception. So now let’s see how Campbell manages to defend the truth of this pair of claims.

. . Attention and feature binding In order to defend the truth of the first claim, Campbell recruits Treisman & Gelade’s )eature Integration Theory of attention )IT , a model of perceptual processing that puts special emphasis on spatial attention as the process that binds features together, enabling the perceiver to consciously experience these features as features of a single bounded object. In the )IT model proposed by Treisman & Gelade, simple visual features such as colour or orientation are first detected and processed pre-attentively and in parallel in modular processing streams called feature maps, a part of the early vision system. Spatial attention comes in as the process responsible for binding together features detected in separate feature maps to one and the same object, which is none other than the object that occupies the location one consciously attends to. Three kinds of empirical evidence are usually appealed to in support of )eature Integration Theory: evidence from visual search tasks, illusory feature conjunctions, and binding impairments following damage in brain areas associated with spatial attention. Regarding the first kind of evidence, a paradigmatic visual search task display is illustrated in figure below, where subjects are instructed to detect the presence of a certain target among a number of distractors. When targets differ from distractors by only one feature, like a black circle among white circles a , the target immediately pops out , and subjects are immediately able to tell if the target is present in the display. Moreover, detec-

 See Treisman & Gelade view of )IT see Tsal .

, Treisman & Gormican

, Treisman

. )or a critical re-

 Attention-based Perceptualist Theories of Demonstrative Thought

tion time does not increase with the number of distractors in the display: no matter how many white circles are added, targets that differ in only one feature will always pop out , and subjects will be immediately able to tell whether the target is present or not. This is a signature mark of pre-attentive, parallel visual processing, which conforms to )IT’s hypothesis that this is how simple visual features are detected and processed in the early vision system.

0 0 0 ü 0

0 0

0 0

0 0

0 0

o 0 o 0• oo 0

b)

)ig. : Experimental design for simple feature and conjunction search tasks

But on the other hand, if subjects are asked to detect a target defined by a conjunction of features, for example, a black circle among black squares and white circles fig. b , they take longer, and detection time increases with the number of distractors in the display. This is a signature mark of slower, attentional serial processing. This once again conforms to )IT’s hypothesis that binding features together requires the allocation of attention to each item in the display in a serial manner, until the horizontal white rectangle is found. The second type of evidence comes from illusory conjunctions of features. In a typical experiment of this kind, subjects are presented very briefly . s with a display such as the one illustrated in figure below, containing two digits on each side of the screen and some coloured shapes in the middle. The task, as explained to participants before stimulus onset, is to report on which digits appear in the display, as well as on all the features they are able to see in one of the four locations occupied by a coloured shape in the middle the relevant location is cued ms after stimulus onset ; but the experimenter explicitly instructs participants to prioritize the digits. In order to follow these instructions in such a short period of time, participants have to divide their attention global-

 But see Wolfe et al.

for a different interpretation of these results.

John Campbell 

ly to the whole display, preventing them from consciously focusing their attention on the location of the coloured shapes in the middle. The prediction of the )IT model is that divided attention should induce binding errors, which is precisely what these experiments have found. In the absence of conscious attention to the location of the coloured shapes, subjects reported a high number of illusory conjunctions, much more often than they reported on features that were not presented at all in the display. If the display contained a blue triangle and a green circle, subjects report more often having seen a green triangle and a blue circle. These results fit very well with the predictions made by the )IT model: the high rate of illusory conjunctions suggest that subjects were able to correctly detect the presence of simple features which is done automatically and pre-attentively , but as the task demands prevented them from consciously allocating their attention to stimuli in the middle of the visual display, features at these locations were incorrectly bound.

)ig. : Experimental design for illusory conjunctions of features from Treisman 99

The third type of evidence comes from binding impairments in patients with parietal lesions. As the parietal lobes are crucially involved in the orientation and control of spatial attention, the )IT model predicts that feature binding in patients with parietal lesions will be severely compromised, which is precisely what was found. The most dramatic evidence comes from studies with patient

 Treisman : . Tsal is skeptical that evidence from illusory conjunctions supports the )IT model, but this debate is beyond the scope of this book. )or detailed information on the role of the parietal lobes in spatial attention see Kastner & Ungerleider .

  Attention-based Perceptualist Theories of Demonstrative Thought R.M., who exhibits symmetrical lesions in each parietal region as a result of two successive strokes. Although the strokes left many of R.M.’s cognitive and visual capacities intact – for example, he has normal visual acuity and is normally able to recognize colours and letters – R.M. suffers from severe impairments in tasks requiring spatial orientation and spatial attention. When R.M. was presented with a simple visual display containing two coloured letters say, a red ‘X’ and a blue ‘T’ and asked to report on the first letter he saw, he made numerous binding errors, reporting on illusory conjunctions a red ‘T’ or a blue ‘X’ much more often than he reported on features that were not presented at all in the display which rules out the hypothesis that he was merely guessing . This fits very well with )IT’s hypothesis that feature binding requires conscious spatial attention, for this is precisely what R.M. is unable to do. In the )IT model, when the subject directs her attention to a certain location in the visual field where a stimulus is presented, this location becomes activated in a master map of locations, where boundaries between regions in the visual field are represented but not which features belong to each region. When this location is activated all features detected at this location in the parallel feature maps are bound together to the same object, yielding a conscious perception of a bounded, unitary object bearing features detected at the attended location. The location occupied by the object where the subject directs his attention to constitutes the binding parameter employed by the visual system in order to bind features detected at that location to one and the same object. The )IT model supports Campbell’s claim that conscious attention is a form of visual selection, and a very ‘direct’ one at that: for if )IT is right, conscious attention is the cause of object perception, the mechanism that makes objects available to be experienced in the first place, rather than a psychological phenomenon that arises once objects have already been visually selected. Moreover, selecting objects in this manner does not require the presence of further representational intermediaries: attention is allocated directly to locations in the external environment, setting this location as a binding parameter and making object perception possible. This is the sense in which conscious attention reaches all the way to the object and brings it into one’s subjective life , as Campbell stated in the analogy with Russellian acquaintance. As a result of this selection process the subject will be in a perceptual state whereby the attended object will be perceived as experientially highlighted, relative to other objects at unattended portions of the visual field. This phenomenal property is a direct  The studies with R.M. are well documented in )riedman-Hill et al. .

and Robertson et al.

John Campbell 

product of this selection process, something we can account for at the level of perception without presupposing thought about objects. Or so Campbell will argue.

. .

Experiential highlighting again

It is important to notice that although Campbell insists on there being a central role for the phenomenal character of conscious object perception to play in a theory of demonstrative thought, he is also careful to point out that the phenomenal character of experience is not a property of the internal states of the perceiver. Rather, it is something that arises only to the extent that perception put us in a relation with objects in the external world. As Campbell puts it, T he phenomenal character of your experience, as you look around the room, is constituted by the actual layout of the room itself: which particular objects are there, their intrinsic properties, such as colour and shape, and how they are arranged in relation to one another and to you. … Two ordinary observers standing in roughly the same place, looking at the same scene, are bound to have experiences with the same phenomenal character. )or the phenomenal character of the experiences is constituted by the layout and characteristics of the very same external objects. We have the ordinary notion of a 'view', as when you drag someone up a mountain trail, insisting that he will 'enjoy the view'. In this sense, thousands of people might visit the very same spot and enjoy the very same view. You characterize the experience they are having by saying which view they are enjoying. … this is the same thing as describing the phenomenal character of their experiences. Campbell :

This picture needs to be made a little more complex in order to incorporate conscious attention, for it is not exactly accurate to say that two ordinary observers standing in roughly the same place, looking at the same scene, are bound to have experiences with the same phenomenal character . If each observer is consciously attending to different parts of the scene, they will most likely have experiences with different phenomenal characters. I take it, for example, that what it’s like to see Paris from the top of the Eiffel Tower while consciously attending to the Panthéon is different from what it’s like to see Paris from the very same spot while consciously attending to the Notre Dame. Otherwise, I have wasted my money going up there a second time because I missed the 0otre Dame. So it does seem plausible to suppose that two experiences of the same visual scene, as seen from the same vantage point, may nevertheless differ in phenomenal

 Attention-based Perceptualist Theories of Demonstrative Thought

character due to a difference in where conscious attention is allocated. This is something our theory needs to be able to accommodate. But I take it that there’s enough room in Campbell’s notion of a view , as formulated in the passage above, to accommodate the effects of conscious attention on the phenomenal character of experience. With the appropriate qualifications, we should be able to say that the view a subject is enjoying at a certain time is not only a matter of the position from which she perceives the scene, but also a function of where in the scene she consciously allocates her attention. Once we incorporate attention into the picture, we can now propose the following view of the phenomenal character of experience: Phenomenal: the phenomenal character of a visual experience of a scene P, had by a subject S at time t, is jointly constituted by the following sets of parameters: The vantage point from which P is seen, relative to an origin and axes centred in the position occupied by S’s body at t Where in P the subject consciously directs her attention at t

This view of the phenomenal character of experience is directly related to the property of experiential highlighting, for consciously directing one’s attention to different portions of the visual field will make objects occupying the attended locations experientially highlighted. So on the basis of ‘Phenomenal’ we may now put forward the following definition of experiential highlighting: ExpHigh: For all subjects S, objects x and times t, x is experientially highlighted for S at t iff x occupies the location where S consciously directs her attention at t.

But although this is on the right track, it cannot be right as it stands. )or merely saying that x occupies the location where S consciously directs his attention at time t is not enough to explain why x should be perceived as experientially highlighted to S. To see why, suppose that we fill all the relevant parameters specified in ‘Phenomenal’ above, which are required in order to determine the phenomenal character of a subject’s experience of P at t: we fix S’s vantage point based on the position she occupies in relation to P at t, as well as where in  This claim is supposed to be neutral on whether every change in phenomenal character brought by a shift of attention corresponds to a change in the representational content of perception, a topic that is hotly debated. See 0anay for a positive answer to this question, and Speaks for a negative one.

John Campbell 

P she consciously directs her attention. As a result, we now have a snapshot of P from S’s point of view at t centred on the object x that occupies the attended location; but being in the centre of a snapshot is not the same as being experientially highlighted. There is nothing in the snapshot itself, or in the fact that a certain object is at its centre, that explains why this object is phenomenally more salient relative to other objects. So what is it exactly about conscious attention to an object that explains why the attended object is perceived as experientially highlighted? Although Campbell does not elaborate much on this point, if we look at the empirical literature on attention there are a number of candidates we can appeal to in order to account for the relation between conscious attention and experiential highlighting. One type of empirical evidence that is directly relevant to our discussion comes from a series of experiments conducted by Marisa Carrasco and collaborators, which purport to show that the allocation of attention to a stimulus alters the appearance of the stimulus by boosting its apparent contrast. This is a change in perceptual appearance that plausibly correlates with experiential highlighting: attended stimuli will be perceived as higher in contrast relative to other unattended stimuli, which will not benefit from this contrast boost. Perhaps, then, for an object x to be perceived as experientially highlighted is for x to be perceived as higher in contrast relative to other objects in the scene. In the experiment illustrated in figure below, subjects are presented with a visual display containing two Gabor patches that differ in perceived contrast, divided by a fixation point in the middle. Subjects are then instructed to indicate the orientation of the grating that is higher in contrast, while maintaining focus on the central fixation point. In a control condition where participants are presented with the Gabor patches without any kind of spatial pre-cueing, they naturally report on the orientation of the right patch, which clearly looks to  Carrasco et al. , Treue . The maintenance of focus on the central fixation point means that the experiment actually probes into the effects of the covert allocation of attention. This is important because it allows us to control for changes in perceptual appearances that are merely due to foveation of the stimulus, something that may be explained simply by the high number of receptor cells in the fovea. But as what we are interested in investigating are not the effects of foveation but the effects of the conscious allocation of attention, the phenomenon of covert attention is a better way to probe into these effects. The covert allocation of attention is known to replicate the effects of foveation in how attended stimulus perceptually appears Yeshurun & Carrasco , while ruling out the possibility that these effects are merely due to the high number of receptor cells in the fovea as opposed to an attentional effect .

 Attention-based Perceptualist Theories of Demonstrative Thought

be higher in contrast. However, when presentation of the stimulus is briefly preceded by a spatial cue at the location where the left stimulus will appear – thus attracting subjects’ covert attention to that location – this stimulus will appear to be higher in contrast, and participants will be at chance in indicating the orientation of either the left or the right stimuli as both will be perceived as equal in contrast .

)ig. : Experimental design for attentional effects on contrast perception from Treue

4

This provides very compelling evidence that the allocation of attention alters the appearance of a stimulus by boosting its contrast, something that may be explained in purely perceptual terms: at the neurophysiological level, the allocation of attention works like a contrast gain, lowering the firing threshold of attending neurons and thus diminishing the required contrast for these neurons to respond to stimuli in the focus of attention. This effectively boosts the strength of the visual signal, making attended stimuli appear to be higher in contrast. Besides contrast, it has also been shown that the allocation of attention enhances brightness Tse , spatial resolution Yeshurun & Carrasco , and accelerates the rate in which stimuli is perceptually processed Carrasco & McElree . These results give some empirical support to ‘ExpHigh’: when a subject consciously attends to the location occupied by an object x in the visual field, this will make x appear to be higher in contrast/brightness/spatial resolution/etc., relative to other objects at unattended locations of the visual field. This is what it means for x to be experientially highlighted, as phenomenally more salient relative to other unattended objects and/or portions of the visual field.  Carrasco et al.

:

, Di Russo et al.

.

John Campbell 



With this account of experiential highlighting in hands, we can make better sense of Campbell’s claim that the phenomenal character of experience is constituted by the external layout of the subject’s external environment, as revealed by the conscious allocation of attention. To borrow Campbell’s own metaphor, we can think of conscious attention as if it were a pane of glass : a transparent medium that makes the external world available to be consciously experienced by the subject, revealing what the world looks like at the locations one points the glass to. So if we imagine that the glass has limited scope, i.e., that it cannot simultaneously occupy the entirety of the visual field, as the glass is placed in certain portions of the scene it will reveal details of the scene behind it at the same time that details that fall outside the scope of the glass will be lost . As a consequence, the subject will consciously experience objects behind the glass as experientially highlighted. But as a transparent medium, the glass itself makes no contribution to the phenomenal character of the experience of seeing through it Campbell : - . These considerations mark the end of our discussion of Campbell’s attention-based perceptualist model. If the exposition was clear enough, we should be now in a position to see how, for Campbell, conscious attention explains demonstrative thought in virtue of the following pair of features: . It is a direct mechanism of visual selection by binding features together and enabling the subject to perceive a single bounded object . It puts the perceiver in perceptual states with the phenomenal property of experiential highlighting, something that can be fully accounted for in terms of facts about where the subject consciously directs her attention through the effects of attention on conscious perceptual experiences as demonstrated by the Carrasco studies Wayne Wu a will deny both of these claims. Conscious attention, according to Wu, cannot explain demonstrative thought because it is not a form of visual selection but a cognitive way of focusing consciousness on objects that have already been perceptually represented. Correspondingly, its associated phenomenology i.e., experiential highlighting is explained as a higher-order feature of experience, arising from what it’s like to cognitively select an object of visual perception. Hence, it cannot be a pre-requisite for demonstrative thought to be possible in the first place. As Wu puts it,

 Attention-based Perceptualist Theories of Demonstrative Thought

Phenomenal salience associated with conscious perception derives in part from cognition. The phenomenal salience of an attended object correlates with one’s perceptual-based demonstrative thoughts about it, specifically a demonstrative awareness that one is attending to that object. Wu a: –

. Wayne Wu ..

Wu’s argument against conscious attention as visual selection

Wu’s argument can be summarized in the following terms: . There is no perceptual feature of what it’s like to attend to objects that explains what it is for an object to be experientially highlighted; but . There is a cognitive feature of what it’s like to think demonstratively about objects that correlates with the property of experiential highlighting; hence . Conscious attention is a cognitive phenomenon, whose phenomenal character derives from the phenomenology of demonstrative cognition. The argument purports to show that if we want to appeal to the psychological notion of attention in an explanation of demonstrative thought, conscious attention cannot be the right tool for the job. In Wu’s picture there is still a role for selective attention to play, but it will require us to think of attention in terms of a psychological-theoretical notion he calls ‘attention as selection for action’ / b . According to this view attention is something built into the very notion of agency: for an agent to act she needs to be able to select a subset of stimuli concurrently presented in the visual scene in order to control the appropriate motor action directed at the selected stimuli. Attention is the process, or set of processes, that make this selection possible. Once stimuli pertaining to a particular object which the agent acts upon have been attentionally selected, the agent will be in a position to ground her cognitive activities in that object, thus thinking demonstratively of it. Experiential highlighting plays no role in the explanation of how grounding is possible: on the contrary, it is something that arises once grounding has already taken place. So now let’s proceed to a more detailed discussion of Wu’s argument.

Wayne Wu 

.. Synchronic and diachronic phenomenal salience We may begin by making a distinction between two notions of phenomenal salience, corresponding to two temporal dimensions of conscious attention. On the one hand, we may say that conscious attention makes an object phenomenally more salient relative to other objects concurrently presented in the visual scene. This is a notion of phenomenal salience that draws on a simultaneous contrast between attended and unattended objects, in which case we shall say that the attended object is ‘synchronically phenomenally salient’. But on the other hand, we may also say that when an object is brought into the focus of attention it becomes phenomenally salient, a notion of phenomenal salience that draws on a temporal contrast between the present state of the object and its past state prior to the conscious allocation of attention. In this case, we shall say that the object is ‘diachronically phenomenally salient’. So which of these two notions of phenomenal salience is at play in experiential highlighting? James described conscious attention as the taking possession by the mind, in clear and vivid form, of one out of what seem several simultaneously possible objects , something that indicates synchronic phenomenal salience. Campbell, however, sometimes speaks of highlighting a portion of the visual field, as when we move from the experience as of a sea of buildings to the experience of a building as experientially highlighted. This suggests a notion of diachronic phenomenal salience, but one way to make these two ideas compatible is this: diachronic phenomenal salience refers to the process of making an object phenomenally salient, whereas synchronic phenomenal salience is a property of the resulting state following this process. Since Campbell appeals to attentional states in his account of demonstrative thought, this suggests that synchronic phenomenal salience is what he has in mind. So let’s start out with the assumption that experiential highlighting amounts to the synchronic phenomenal salience of an object in experience, and see how far it takes us. Section . . above suggested that it might be possible to explain experiential highlighting in terms of the effects of conscious attention in the way stimuli perceptually appears as demonstrated by the Carrasco studies . This means that we should be able to explain the synchronic phenomenal salience of an object in these terms. But the problem is that if we look closely to these experiments, we’ll see that they are more naturally associated with a notion of diachronic phenomenal salience. In the contrast experiment with the Gabor patch-

 Wu

a:

- .

 Attention-based Perceptualist Theories of Demonstrative Thought

es, for example, Carrasco et al. describe a situation where the covert allocation of attention to the left gabor patch makes it appear to be higher in contrast relative to its prior appearance, not relative to the other, unattended gabor patch on the right which is perceived as being equal in contrast . This suggests a notion of diachronic phenomenal salience, but it is not immediately clear that the same results may also be used to account for synchronic phenomenal salience. To see why, suppose we say that synchronic phenomenal salience can also be explained using Carrasco’s experimental results: that conscious attention to an object x will make x appear to be higher in contrast relative to another unattended object y, which will not benefit from this contrast boost. But of course, we need not restrict our explanation to contrast effects; as similar results have also been found for other visual features such as brightness and spatial resolution, we can introduce a higher-order variable  that ranges over all visual features whose appearance is enhanced by the allocation of attention. In this picture, to explain synchronic phenomenal salience in perceptual terms would require one to defend the truth of the following claim: Perceptual synchronic phenomenal salience PSPS : For all subjects S, objects x and y, and times t, x is synchronically phenomenally salient for S at t iff S’s conscious allocation of attention to x at t makes x appear to be higher in  relative to y

But as Wu points out, PSPS cannot be true: x appearing to be higher in  relative to another concurrently presented object y is neither necessary nor sufficient for x’s synchronic phenomenal salience. After all, it is perfectly possible for an object x to be synchronically phenomenally salient due to the conscious allocation of attention even if x appears to be lower in  than other objects in the visual field. Just imagine, for example, consciously attending to x in a poorly illuminated and distant corner of a room while simultaneously having a range of well illuminated objects right in front of your eyes, all of which appear to be higher in  relative to x. But since x may still be synchronically phenomenally salient through the conscious allocation of attention, PSPS cannot be true as it stands. But here a proponent of Campbell’s theory may object. The claim that synchronic phenomenal salience may be perceptually explained is not meant as a claim that x being phenomenally more salient than y is just a matter of x appearing to be higher in  relative to y; the effects of attention in the way stimuli per Wu

a:

.

Wayne Wu 

ceptually appear do not make a direct contribution to synchronic phenomenal salience in this manner. Rather, the strategy would be to explain diachronic phenomenal salience using Carrasco’s studies, and then proceed to explain the synchronic phenomenal salience of the object on the basis of its diachronic phenomenal salience. After all, the diachronic phenomenal salience of an object also seems to imply its synchronic phenomenal salience: if we shift attention to an object and make it phenomenally more salient relative to its prior state before the allocation of attention, we also make it phenomenally more salient relative to other objects in the scene. Therefore, the idea would be to explain the diachronic phenomenal salience of an object through Carrasco’s studies, and on this basis extract its synchronic phenomenal salience since the former implies the latter . To make matters clearer, let’s start by assuming the following view of diachronic phenomenal salience: Perceptual diachronic phenomenal salience PDPS : For all subjects S, objects x and times t and t+, x is diachronically phenomenally salient for S at t+ iff S’s conscious allocation of attention to x at t+ makes x appear to be higher in  relative to its prior appearance at t.

PDPS is not vulnerable to Wu’s objection against PSPS. Regardless of how other objects in the visual scene perceptually appear, Carrasco’s studies have clearly demonstrated that consciously attending to x will make x appear to be higher in  relative to is appearance prior to the allocation of attention. This explains what it is for x to become diachronically phenomenally salient from t to t+. And since its diachronic phenomenal salience implies its synchronic phenomenal salience, this accounts for its synchronic phenomenal salience as well. This allows us to explain an object’s synchronic phenomenal salience through its diachronic phenomenal salience, without having to say that x being synchronically phenomenally salient is just a matter of x appearing to be higher in  relative to y. We thus end up with the following view of synchronic phenomenal salience: Perceptual synchronic phenomenal salience II PSPS II : For all subjects S, objects x and y and times t and t+, x is synchronically phenomenally salient for S at t+ relative to y iff S’s conscious allocation of attention to x at t+ makes x diachronically phenomenally salient for S relative to x’s prior appearance at t.

 The converse, however, is not true: an object may be phenomenally more salient relative to other objects in the scene without it being phenomenally more salient relative to its prior state we could maintain it phenomenally salient through sustained attention .

  Attention-based Perceptualist Theories of Demonstrative Thought But unfortunately this strategy will not work either; diachronic phenomenal salience is explained in terms of changes in the perceptual appearance of x across different times, but it doesn’t seem to be required, for x to be synchronically phenomenally salient at a time t+, that x has changed its appearance from t to t+. It is perfectly possible, for example, for x to retain its perceptual appearance from t to t+, as we sustain attention on it throughout this time. The problem is clearly formulated in the following passage from Wu: When we maintain attention to one of the [objects] without making further shifts of attention, the attended [object] remains synchronically salient even if nothing about it changes over the relevant period of time. Yet in the absence of any changes in salience, the notion of diachronic salience doesn’t get a grip as that notion is tied to the perceptible changes in an object over time. … So where attention doesn’t shift over time but is maintained on an object, there is no change in the diachronic salience of any object, yet the attended [object] is synchronically salient. Wu a:

These considerations falsify both versions of PSPS; for any visual feature  whose appearance may be altered by the allocation of attention, x may be synchronically phenomenally salient for S even if x does not appear to be higher in  relative to another object y, or higher in  relative to its prior appearance. We are then led to conclude, with Wu, that there are no purely perceptual effects of conscious attention that plausibly correlate with the synchronic phenomenal salience of an object in experience. If we want to account for this phenomenal property we must appeal to extra-perceptual features.

..

The cognitive view of synchronic phenomenal salience

In order to understand Wu’s cognitive account of synchronic phenomenal salience, we may begin by drawing a distinction between two different dimensions of conscious attention: on the one hand, there is an obvious perceptual element in conscious attention, manifested in how attention changes the way we perceptually experience the world. As we explore the layout of our external environment by consciously attending to different portions of the visual field, we bring to the forefront of our experience different portions of our environment through the conscious allocation of attention. When we do this, we come to experience the attended objects and features in a different manner: the experimental results from the Carrasco studies present us with compelling evidence that conscious attention alters the way stimuli perceptually appear by boosting their contrast/brightness/spatial resolution etc.

Wayne Wu 

There is, however, another important dimension to conscious attention, which is also emphasized in James’ original characterization: this is the agentive dimension, which stresses that conscious attention is a form of voluntary, goaldirected action, with the distinctive phenomenology that characterizes an action’s being voluntary. In consciously attending to x one is typically aware of oneself as an agent, as someone who is actively doing something rather than someone to whom things are happening: one is typically aware that one is attending to the object in question. This agentive element is what’s behind James’ observation that conscious attention is a form of active selection of objects involving an element of concentration, which is of course a feature of agentive experience: a feeling of effort and concentration is part of the phenomenal character of an experience of intentionally doing something. Indeed, it seems hard to find cases where conscious attention is divorced from the agentive experience of attending. Although there are forms of selective attention that do not give rise to agentive experience as demonstrated by the Kentridge studies with blindsight patients , a constitutive element of what makes something an act of conscious attention is that one is typically aware of what one is doing in respect to the attended object. When one consciously shifts one’s attention to x as opposed to y, w or z , or consciously maintains attention focused on x, one experiences oneself as the agent of these actions, and one is typically aware that one is shifting/maintaining attention on x as one intends to. In addition, we’ve also seen that conscious attention is characterized by its distinctive phenomenology, i.e., the synchronic phenomenal salience of an object. So with these two dimensions of conscious attention in hands, we may ask: what phenomenal features of conscious attentional experience account for the synchronic phenomenal salience of the attended object? Wu has already argued that perceptual effects alone are unable to account for the synchronic phenomenal salience of an object; therefore, the obvious alternative would be to look for a feature of the agentive experience of conscious attention, which is exactly Wu’s strategy in arguing for a cognitive view of synchronic phenomenal salience. According to this view, the synchronic phenomenal salience of an object is a feature of cognition, brought by the agentive dimension of conscious attention. We shall soon explore a bit more what it means for the agentive experience associated with conscious attention to be cognitive in nature, but for now let us focus on the contribution of agency to the phenomenal salience of an attended object. As a contrast case, take the study of goal-directed mechanisms of covert attention carried out by Michael Land , where subjects do not report having a feeling of agency. In a series of experiments, Land recorded subjects’ eye

 Attention-based Perceptualist Theories of Demonstrative Thought

movements with a head-mounted eye tracker as they were actively engaged in a series of everyday tasks. What he found was that when an agent is engaged in a certain task, her eyes will make a series of quick ballistic movements one to four times per second across the scene in a way that is intelligibly related to the task at hand. If the agent, for example, is engaged in the task of making a cup of tea, as she walks into the kitchen her eyes will quickly move to the spatial locations where the items needed to execute the task are most likely to be located, such as the cupboard where tea is located , the sink to gather water the stove where the kettle will be boiled , and so on. If, however, the task is to make a sandwich, the agent’s eyes will quickly move to the refrigerator, the utensils drawer, the counter, etc. The standard explanation is that these eye movements are guided and controlled by mechanisms of covert attention. Each of these ballistic movements is preceded by a covert attentional shift to the location where the eyes will move next, which sets the spatial parameter for the saccade to follow. This prevents random and wasteful eye movements, as this covert attentional shift will initiate a saccade only if it is accompanied by a go signal that conveys the presence of a potentially behaviourally relevant target at the attended location. Otherwise, the eye is inhibited from moving and attention is covertly shifted elsewhere. Moreover, as argued by Hoffman, this attentional mechanism is quite plausibly the same mechanism of covert spatial attention studied in the Carrasco experiments, responsible for altering the perceptual appearance of visual stimuli. As Hoffman puts it, The evidence favors the parsimonious view that there is a single covert orienting mechanism responsible for both perceptual enhancement and programming of eye movements. Hoffman :

However – and this is what is important for Wu’s argument – a subject in a Land experiment is not typically aware of covertly shifting attention in the manner recorded by the eye trackers. In fact, she would be quite surprised to learn about the frequency and speed in which her eyes move across the scene, as well as to all the locations covered in such a short period of time. As expected, these covert attentional shifts will not make attended objects synchronically phenomenally salient either, something that gives support to Wu’s claim that phenome Land . The patterns of eye movements for the tea-making task are diagrammed in page . )or the sandwich-making task Land appeals to experimental results reported in Hayhoe . Hoffman , Kowler et al. .

Wayne Wu 

nal salience is closely associated with the agentive experience of attending. )or an experience with this phenomenal character to occur, it is required that attention be deployed in a conscious and voluntary manner, i.e., that the attentional shifts in question be experienced as one’s own action. But here one may object: what about cases where attention is automatically drawn to an object that has suddenly appeared in the scene? Here there doesn’t seem to be any intentions on the part of the subject to attend to this or that object. Although a full discussion will have to wait until section . . , for now we can just mention that these cases also involve an element of agentivity: one is typically aware of shifting attention to the new object, even if the action is exogenously initiated. Once attention has been automatically drawn to the object one will be also aware of maintaining attention focused on that object, for the purposes of assessing it for behavioural relevance. So even in automatic attentional capture one still experiences the action as one’s own. Based on these observations, Wu argues that synchronic phenomenal salience is a higher-order feature of experience built up from both perceptual and agentive elements of conscious attention. When attention is consciously allocated to an object x, x will be perceived in a certain manner i.e., as having a certain colour, shape, spatial position etc. , and, quite plausibly, as having some of its perceptual features enhanced by the allocation of attention. But one will also have the experience that one is consciously attending in this manner, something that makes a difference to how the object is experienced: it is experienced as the object one consciously attends to, as the target of one’s conscious, intentional actions. This distinctive way in which an object is experienced in conscious action, according to Wu, is what explains its synchronic phenomenal salience. This account avoids the problems of PSPS we’ve seen in section . . above, which relied on changes in the perceptual appearance of an object x caused by the allocation of attention. Regardless of the effects of conscious attention on the way x perceptually appears, x may still be synchronically phenomenally salient to a subject S due to an awareness that x is the target of S’s conscious action of attending. In order to accommodate synchronic phenomenal salience in an account of conscious attention, Wu proposes an impure representationalist theory that appeals to both representational content and psychological mode. This allows him to say that synchronic phenomenal salience is not a feature of representational content which just represents the attended object bearing certain features but of what Wu calls the ‘cognitive demonstrative mode’. Roughly speaking, to represent an object x in a cognitive demonstrative mode is to represent x with an awareness of x as the target of one’s conscious thoughts and actions, an

 Attention-based Perceptualist Theories of Demonstrative Thought

awareness that comes from the agentive experience of consciously attending to x. But this awareness does not arise in virtue of any property attributed to x in representational content. It is, rather, a feature of the cognitive demonstrative mode. The idea that the psychological mode makes a contribution to the overall phenomenal character of experience is already familiar to those that employ the mode/content distinction. In Recanati’s framework briefly discussed in chapter one, for example, the feeling of presence that is characteristic of visual perception, as well as the feeling of pastness that accompany episodic memories, are features of experience that arise from the perceptual and mnemonic mode respectively. As Recanati puts it, The mode also contributes to the phenomenology, since the mode is something the subject is aware of. In the memory mode, the content is presented as true with respect to a past perceptual situation, hence the scene represented is felt as past. In the perception mode, the content is presented as true with respect to the current perceptual situation, hence the scene represented is felt as present. Recanati : -

In a similar vein, we may say that conscious attentional experience presents the attended object as synchronically phenomenally salient, which is a feature of the cognitive demonstrative mode. More specifically, of the agentive dimension of the mode. In addition – and this is a crucial step in Wu’s cognitive account of synchronic phenomenal salience – this way of experiencing the object is cognitive in nature, since it cannot be explained in terms of changes in the perceptual appearance of the attended object, but arises out of one’s agentive experience of cognitively engaging with it. It is an awareness that this object, rather than any other in the visual scene, is at the center of our cognitive activities shifting and maintaining attention to it, orienting oneself in relation to it, planning further actions on it, and so on . This is what makes the object synchronically phenomenally salient. As Wu puts it, The attended object … anchors such broadly cognitive activity. One is in general then aware of what one is variously doing, activities that are united by a common anchor: the attended object. To the extent that these states make a subjective difference to the subject, they do so because the selected object rather than others is at the center of explanations of that subjective difference. That is, the subject is demonstratively cognitively representing that object and not others concurrently perceived. Wu a:

But to represent an object in a cognitive demonstrative way is nothing other than to have a demonstrative thought about it remember: demonstrative

Wayne Wu 



thoughts are attention-based mental activities with singular demonstrative contents . Correspondingly, the synchronic phenomenal salience that comes with it will be nothing other than the phenomenology of demonstrative thought. )or when we think about a particular object in our external environment we are not just aware of its perceptible features. We’re also aware of what we are doing in respect to that object, i.e., thinking about it, cognitively engaging with it. We’re aware that this object is the target of our cognitive activities. Therefore, it makes sense to say that this form of agentive experience is cognitive in nature, and that the corresponding mode in which the object is experienced is a cognitive demonstrative mode. But if in order to explain synchronic phenomenal salience we need to appeal to this form of cognitive awareness, then synchronic phenomenal salience cannot be what explains how demonstrative thought is possible in the first place. Rather, the order of explanation is effectively reversed: it is the agentive awareness that comes from our thinking demonstratively about objects that explains their synchronic phenomenal salience, and not the other way around. To conclude, Wu’s arguments suggest that conscious attention cannot be what explains demonstrative thought under the perceptualist constraint. It is a phenomenon that has its roots in demonstrative cognition, not perception, and that presupposes that objects have already been perceptually selected in order to be acted upon. Its distinctive phenomenology, characterized in terms of synchronic phenomenal salience, is just the phenomenology of demonstrative thought, and can be explained in the following way: Cognitive synchronic phenomenal salience CSPS : For all subjects S, objects x and y and times t, x is synchronically phenomenally salient for S at t relative to y iff S is cognitively aware of x at t as the target of S’s cognitive activities.

..

The agentive view of synchronic phenomenal salience

But here one may object: even if we grant that there is a constitutive agentive element in conscious attention, and that, quite plausibly, this agentive dimension has an important role to play in accounting for synchronic phenomenal salience, why suppose that the agentive awareness involved in consciously attending to an object must be cognitive in nature? I see two main problems with this proposal. )irst of all, Wu says that when we think demonstratively of an object we are also aware of what we are doing in respect to the object, i.e., thinking about it.

 Attention-based Perceptualist Theories of Demonstrative Thought

But this assumes that episodes of thinking are accompanied by a sui generis cognitive phenomenology of thought, which is a controversial claim. It is not obvious, for example, that judging ‘this perceptually presented chair is white’ comes with a characteristic ‘judging’ feeling distinct from the phenomenology of perceiving a white chair. It is far from clear that taking the chair to be white must also involve an awareness of ourselves judging that the chair is white, or an awareness of the chair as the target of our judgment. Even if there are important differences – as argued in chapter one – between perceptual states and demonstrative mental states, it is not clear that these differences may be cashed out in terms of differences in the phenomenal character of what it’s like to think about objects as opposed to merely perceive them. Therefore, it’s not completely clear that thinking demonstratively of objects will necessarily give rise to a distinctive cognitive phenomenology. This is a more substantial claim, that needs to be argued for. Secondly, it is one thing to say that synchronic phenomenal salience cannot be explained by changes in the way visual stimuli perceptual appears, and that the agentive dimension of conscious attention needs to be brought in in order to complement the explanation. I am quite happy to accept this point; but does this establish the stronger conclusion that the agentive phenomenology that helps account for synchronic phenomenal salience must be cognitive in nature? What exactly is the argument for that? Unfortunately, Wu does not elaborate much on the cognitive nature of our experience of acting on objects, other than acknowledging in a few footnotes that this is a complicated question that demands further work. The few clues we have on this respect tell us that Wu employs ‘cognitive’ in a contrasting sense, in order to point out that the experience of consciously attending to objects cannot be reduced to the perceptual phenomenology that accompanies our perception of the object’s visible features its colour, shape, size, etc. . But he is happy to concede that this is a rough distinction, and that further investigation might make us further distinguish between the phenomenology of objectdirected intentional action and the phenomenology of demonstrative thought. This is a plausible point, but it is a surprising concession: for if we acknowledge that the phenomenology of object-directed intentional action may differ from the phenomenology of demonstrative thought, then Wu’s argument  See the essays in Bayne & Montague issue. Wu a: fn, fn. Wu a: fn.

for a good overview of different positions on this

Wayne Wu 

that synchronic phenomenal salience presupposes demonstrative thought will no longer hold. )or we may now say that it is the phenomenology of objectdirected intentional action what accounts for synchronic phenomenal salience, which in turn explains how demonstrative thought is possible. But as it is still unclear what would be the nature of this agentive phenomenology, I will not push Wu on this point. Rather, I would like to focus on the contrasting sense of ‘cognitive’: what makes us so sure that the kind of agentive awareness involved in object-directed action cannot be perceptual in nature? Although Wu does not say too much about it, he does make a quick reference to Shoemaker’s arguments against perceptual models of introspection , where he argues that it would be wrong to take our awareness of our own cognitive life including our actions to be perceptual in nature. But the appeal to Shoemaker here is simply changing the subject, and conflating two different questions that should be kept apart. Shoemaker is primarily concerned with providing a philosophically adequate account of introspection, one that does not presuppose that knowledge of our own mental states must be a result of some kind of inner perception. In this sense, Shoemaker’s question concerns the kind of access we might have to our own mental life, but the question here is a different one: we are concerned with the nature of agentive experience in object-directed intentional action and its contribution to phenomenal salience, not with the kind of introspective access we have to our experiences of agency. In this sense, saying that we do not have a perceptual access to our experiences of agency, as Shoemaker does, is not the same as saying that our agentive experiences of intentionally acting on objects cannot be a part of our perceptual experiences of these objects. Indeed, some philosophers take the phenomenal character of perceptual experience to include the experience of agency. Horgan et al., for example, talk of an interpenetration of object-perception experience and doing-experience : , and of perceptual experience being “infused with a distinctive voluntary-agency phenomenal character : . )or Horgan et al. the phenomenal character of perception includes the experience of oneself as an embodied agent who actively interacts or is capable of interacting with objects in one’s external environment. This agentive dimension of perception is especially clear when we’re actively engaged with an object, and where the object is perceived as the object we act upon. As the authors put it,

 Wu

a:

fn.

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 Attention-based Perceptualist Theories of Demonstrative Thought

In experiencing yourself as acting voluntarily, typically you perceive certain objects in the world in a distinctive way—viz., as things toward which, or on which, you act. Horgan et al. :

This distinctive way in which objects are perceived when we act upon them plausibly correlates with their synchronic phenomenal salience. When we are actively engaged with a particular object x, we momentarily withdraw ourselves from other objects in order to deal more effectively with x. This will make x be perceived in a distinctive way, namely, as the target of our actions, which explains its synchronic phenomenal salience. 0othing in this explanation requires us to say that this agentive experience must be cognitive in nature. Of course, not everyone will agree with Horgan et al.’s views on the phenomenal character of visual perception, and it is not my goal here to engage in a full discussion of the nature of our agentive and perceptual experiences. The point of this brief excursion was just to show that being aware of x as the object one acts upon does not necessarily mean being aware of x in a cognitive demonstrative way. An alternative view, suggested by Horgan et al, would be to take this agentive element to be an ineliminable aspect of the phenomenal character of perceptual experience, in which case we could have a perceptual account of synchronic phenomenal salience after all. To sum up, I believe Wu is right in emphasizing the agentive dimension of conscious attention in an account of its distinctive phenomenology. Quite plausibly, part of what it is for an object to be synchronically phenomenally salient in one’s experience is that we’re consciously acting on this object rather than another, and that we’re aware of doing so. But we can grant this point while remaining uncommitted as to whether this form of phenomenal awareness of objects is cognitive or perceptual in nature, or perhaps something different altogether, not easily assimilated in one category or the other. One way to capture the merits of Wu’s account while avoiding its pitfalls would be to propose an agentive account of synchronic phenomenal salience. This would leave an important role for the experience of agency to play in the phenomenology of conscious attention, while still leaving open the exact nature of agentive experience in object-directed actions. The resulting account could be neutrally formulated along the following lines: Agentive synchronic phenomenal salience ASPS : For all subjects S, objects x and y and times t, x is synchronically phenomenally salient for S at t relative to y iff S is agentively aware of x at t and not y as the target of S’s actions.

Wayne Wu 

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As formulated, ASPS is compatible with Campbell’s claim that the phenomenology of conscious attention can be accounted for in terms of facts about where the subject directs his attention to, if we include in these facts the agentive experience of directing one’s attention to the location in question or to the object in that location . And if we decide, following Horgan et al.’s suggestion, that this agentive experience is part of what it’s like to perceive objects, we might rehabilitate Campbell’s idea that conscious attention to objects explains demonstrative thought in virtue of its distinctive phenomenology. As the demonstrative thought is directly based upon a conscious attentional experience, it will inherit the phenomenal character of this experience, which explains Wu’s inclinations to tie the phenomenal character of conscious attentional experience to the phenomenology of demonstrative thought. But notice that we have once again re-reversed the order of explanation: it is only because conscious attentional experience presents an object as synchronically phenomenally salient that the corresponding demonstrative thought will also have this distinctive phenomenal character, and not the other way around. But of course, whether this modified version of Campbell’s account is true or not will hang on how we analyse ASPS above. Defending a perceptual account of ASPS would require an independently motivated account of agentive experience in intentional object-directed action as being perceptual in nature, something that would demand substantial further work. But since Wu’s own proposal to account for demonstrative thought makes no appeal to conscious attention or to its distinctive phenomenology, one advantage of adopting his view is that we are no longer required to make a decision on whether the agentive experience that contributes to the phenomenology of conscious attention is cognitive or perceptual in nature. In fact, if Wu is right conscious attention might simply be explanatorily idle.

..

Attention as selection for action

As we’ve seen so far, the standard way to characterize conscious attention is in terms of a certain perceptual state, distinguished by its phenomenology: the phenomenal salience of the attended object. Wu’s account, however, suggests a different way of approaching the study of attention, which focuses on the notion of agency. In this picture, attention is something built into the very notion of agency, so that when we posit the existence of agents in the world we are already positing the existence of attentional mechanisms. Any creature capable of action must be able to select a subset of perceptual inputs in order to drive

  Attention-based Perceptualist Theories of Demonstrative Thought the appropriate motor outputs to execute the action in question; attention is just the process or set of processes that makes this selection possible. Consequently, what it is for this creature to attend to this or that object at a time cannot be determined in abstraction from the actions the creature is performing towards this or that object. To speak of attention , Wu tells us, is to speak of a way that the subject is attuned during action to relevant information such that it is deployed to inform the subject’s response. And of course, to be attuned to relevant information is nothing other than to be able to select the relevant information while simultaneously filtering out irrelevant information where the ‘relevance’ of information is always relative to the task at hand . This idea can be made clearer in the following passage from Alan Allport, from whom Wu borrows the whole idea of attention as selection for action: Any goal-directed action requires the specification of a unique set of time-varying parameters for its execution – parameters that determine the outcome as this particular action rather than any other: as this particular vocative or manual gesture, this particular directional saccade, and so forth. Consider now what is required if these parameters are to be controlled by sensory say, visual information. Suppose that visual information has to guide manual reaching, for example, to grasp a stationary object or to catch a moving one. Clearly, many different objects may be present in the visual field, yet information specific to just one of these objects must uniquely determine the spatiotemporal coordinates of the end-point of the reach, the opening and closing of the hand, and so on. Information about the position, size and the like of the other objects in view, and also available, must not be allowed to interfere with that is, produce crosstalk affecting these parameters—though they may need to influence the trajectory of the reach in other ways. Consequently, some selective process is necessary to map just these aspects of the visual array, specific to the target object, selectively onto the control parameters of the action. Allport :

Attention, as the passage above makes clear, is the selective process mediating input where this includes not only perceptual information from external objects, but also information concerning the states of one’s own body and output typically, a motor action , in a way that is intelligibly related to the agent’s goals. Therefore, it cannot be understood in abstraction from the agent’s actions. Attention always involves selection of inputs for something, in the service of the subject’s actions in a certain context. 0otice that this account is very dif-

 Wu b: . Page numbers refer to the electronic version of the final draft of the paper from the author’s website http://www.cnbc.cmu.edu/~waynewu/Research_ _files/WUAAS. .pdf .

Wayne Wu 

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ferent from traditional ‘limited capacity’ views, where attention is conceived as a filtering mechanism designed to protect a system of limited capability i.e., the human brain from a computational overload in the face of more stimuli than it can process. In this picture processing systems with unlimited capacity would have no need for attention. In the ‘selection-for-action’ view, in contrast, the need for attentional mechanisms is orthogonal to processing capacity, and directly tied to the necessities of selecting a subset of stimuli and a specific motor action in order to generate coherent behaviour. To make this idea clearer, imagine for example that during a dinner party you are faced with two glasses of water on both sides of your plate, and your goal is to drink from one of these glasses. Abstracting a little for ease of exposition, we may say that at this time, and relative to this task, your relevant behavioural space is constituted by four different possible courses of action: to drink from the right-side glass with your right or your left hand, or to drink from the left-side glass with your left or your right hand. In order to make a move in this behavioural space at this time , you need to be able to select the appropriate inputs – from just one of the water glasses – in order to drive the appropriate motor output, i.e. to drink with the right or the left hand. With these ideas in mind, Wu proposes the following definition of attention as selection for action: )or all subjects S, appropriate item objects, properties, spaces, etc. X, and times t: SfA S’s attention to X is S’s selection of X so as to solve the Many-Many problem present to S at t, namely selection of X inherent in S’s traversing a specific path in the available behavioural space at t i.e., S selects X for action . Wu b:

0ow that we have a better notion of what the ‘selection-for-action’ view consists in, how can it be used in an explanation of demonstrative thought? In order for one to think demonstratively of a particular object x, it is required that information from x as opposed to information from other objects be selected in the visual field, so attention must be somehow involved in this process. But Wu denies that the kind of attention that is needed here is conscious attention. In order to contrast Wu’s account with Campbell’s, let’s return to the sea of buildings example; at time t you gaze distractedly at the urban landscape below, experiencing a sea of buildings but without selecting any particular building  Limited capacity theorists explicitly acknowledge this point; see for example Broadbent : . The ‘Many-Many problem’ is the problem of sifting through many inputs and many potential outputs so as to generate coherent behavior, as illustrated by the water glasses example.

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 Attention-based Perceptualist Theories of Demonstrative Thought

as opposed to another. But when a building is visually selected at t+ you are in a position to think demonstratively about it. What mediates the transition from the sea of buildings experience to the demonstrative thought? Campbell says it is the experience of the object as synchronically phenomenally salient, but here’s what the ‘attention as selection for action’ view would say: At some point during the sea of buildings experience, let’s suppose you decide to inspect the landscape in more detail, starting by visually examining the farthest building on the right portion of the landscape. You now have an intention with a descriptive content – to visually examine the farthest building on the right side of the visual scene. This descriptive intention acts as a goaldirected attentional mechanism, shifting attention to that portion of the visual field and allowing selection of perceptual information from a particular building in that location. The way the descriptive intention guides attentional selection can be explained through a few different neurophysiological processes, for which we have good empirical evidence. )irstly, the allocation of spatial attention to a certain location in the visual field increases the firing rates of neurons that respond to that location in extrastriate and parietal areas, allowing stimuli in that location to be processed faster and deeper. Secondly, a stored representation of the target object in this case, a building is activated in working memory, and remains active during the whole search task. During this time, electric signals are constantly sent from working memory to the visual cortex, enhancing the activation of cortical neuronal assemblies that encode typical features of buildings ‘rectangular’, ‘vertical’, etc . In this manner, things at the attended location that exhibit these features will have a better chance of being selected and be made available to the higher cognitive processes, while irrelevant information will be more easily filtered out. Once information from a particular building has been selected in this manner, you are now in a position to maintain your attention focused on this building, visually examine it, plan a course of action in relation to it, etc. Your intention now has a demonstrative content: you no longer intend to visually examine ‘the building that is farthest on the right in the visual field’, you intend to visually examine that building which has been visually selected. In other words, you come to think demonstratively of it. But here we have gone directly from the sea of buildings to the visual selection of the building and to the correspond-

 Hopfinger et al. , Treisman , Reynolds at al. . Duncan & Humphrey , Driver & )rith , Hollingworth & Henderson

.

Wayne Wu 

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ing demonstrative thought without ever mentioning the building’s synchronic phenomenal salience. As Wu puts it, All that seems to be required to move from the descriptive to the demonstrative intention is consciously given inputs and a goal-directed mechanism of selection … that allows certain information to control and anchor thought. It is not clear what is missing in this generative story that synchronic phenomenal salience would provide. Wu a:

But here a proponent of Campbell’s theory may object: the building example explores a case of endogenous, top-down control of attention, where visual selection is driven by a previously formed descriptive intention to ‘examine the building that is farthest on the right in the visual field’. In this case, it is not difficult to make the transition from the descriptive intention to the selection process on the basis of the neurophysiological mechanisms reviewed above and then to the demonstrative thought, without passing through the building’s synchronic phenomenal salience. But what about cases of exogenous attentional capture, when attention is automatically captured by the sudden appearance of a new object in the scene? In these cases there are no previous intentions to select an object for some purpose or another; it’s just something that automatically happens to the subject. Isn’t that a problem for the ‘selection-for-action’ view? But the fact that attention was automatically captured does not mean that the subject’s intentions are not involved: an action may be exogenously initiated and be guided by the subject’s intentions at the same time. Here’s an example: imagine that you are high up on a rock looking down on the ocean, ready to dive. 0ow, normally you are an excellent diver, except that you have only dived in swimming pools and you are terrified of the ocean. So you freeze, and cannot make the jump. Suddenly, someone gets impatient with your procrastination and pushes you off the rock. At first you fall rather clumsily, but in mid-air you manage to bring your diving skills to bear and manage to orient your body in a way that would ensure a graceful and elegant fall on the water below. Here we have an action that is exogenously initiated you did not intend to jump at that moment , but that once initiated, the movements of your body as you orient yourself to fall are guided by your intentions to fall gracefully on the water. In a similar vein, we may say that when a new object appears in the scene attention is indeed automatically drawn to it. 0evertheless, the subject is involved in her intentions to sustain attention on this object for the purposes of assessing it for behavioural relevance. Her intentions to inspect the object guide the way she orients herself in respect to it in order to visually examine it, once

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 Attention-based Perceptualist Theories of Demonstrative Thought

her attention has been automatically drawn to it. As before, we can go from the initial event that attracted one’s attention – the object appearing in the scene – to the selection of the appropriate object for the purposes of inspection and to the corresponding demonstrative thought without going through the object’s synchronic phenomenal salience. To conclude, it doesn’t matter if we end up explaining synchronic phenomenal salience at the more primitive level of perception or not; from everything that’s been said so far, it might be that conscious attention plays no causal role in grounding demonstrative thought after all. This conclusion, however, would be too hasty. If the problem raised by Wu is that the phenomenology of conscious attention plays no relevant explanatory role, it might be possible to drop it from our theory without dropping the notion of conscious attention altogether. We can say, for example, that particular acts of conscious attention on the part of the subject select objects in the world and make demonstrative thoughts possible, synchronic phenomenal salience no longer playing a significant explanatory role. This is exactly James Stazicker’s proposal , which I shall examine in the next section of the chapter.

.

James Stazicker

. .

Conscious attention without synchronic phenomenal salience

In order to see how we can abandon the problematic notion of synchronic phenomenal salience without abandoning conscious attention altogether, we need to make a distinction between particular acts of conscious attention on the part of a subject, and the effects these acts of attention will bring about. With this distinction in place, we can now say that a particular act of conscious attention will select an object in the world and make it available to be experienced by the subject, while the synchronic phenomenal salience of the attended object will be an effect of this act. But it is the act, and not the effect, which is explanatorily prior to demonstrative thought Stazicker : . Therefore, we can safely abandon the phenomenology of conscious attention from our theory without having to abandon the explanatory role of conscious attention altogether. Stazicker, following Campbell, proposes that particular acts of conscious attention select objects in the world by setting subpersonal perceptual mechanisms into motion that will bind together features of the attended object and allow one to perceive them as features of a single bounded object Stazicker : . The operation of these mechanisms will typically have two effects: the attended object will be perceived in more detail, i.e., as higher in contrast,

James Stazicker 



brightness, spatial resolution, etc. a perceptual effect and the subject will come to think demonstratively of it a cognitive effect . This story leaves it open whether synchronic phenomenal salience can be ultimately cashed out in terms of perceptual effects alone as Campbell would argue , or if we need to bring in the cognitive effects of demonstrative thought in order to explain it as Wu claims . As these two effects will be simultaneously felt by the subject, it is only normal that we have trouble disentangling the perceptual from the cognitive aspects of the phenomenology of conscious attention on introspection alone. But if we follow Stazicker we are no longer required to do so: the explanatory burden now falls on particular acts of conscious attention, regardless of their distinctive phenomenology. Recall that one advantage of Wu’s theory was that it did not require us to make a decision on the nature of agentive experience and its role in synchronic phenomenal salience, since this notion no longer played any role in the theory. This move, however, led us to abandon the notion of conscious attention altogether, and look for alternative accounts of attention. Stazicker’s view offers us a similar advantage, while still acknowledging a role for conscious attention to play. As long as we are careful to distinguish acts of conscious attention from their effects, we can unproblematically say that the former, but not the latter, is what accounts for demonstrative thought under the perceptualist constraint. Conscious attention could provide us with a direct mechanism of visual selection, making objects available to be consciously experienced and putting one in a position to have demonstrative thoughts about them. Wu’s arguments, which are primarily directed against the explanatory role of synchronic phenomenal salience, have no bite against this claim. Recall the building example Wu employs in order to motivate his view. With attention-as-selection-for-action functioning as a goal-directed selection mechanism, we were able to explain how a subject may visually select a building and think demonstratively of it without ever mentioning the building’s synchronic phenomenal salience. But there is nothing in this picture that Stazicker needs to disagree with. Recall that in Wu’s example, the selection mechanism is itself guided by the subject’s conscious descriptive intention. This allows us to say that it is an act on the subject’s part, to consciously direct his attention to the location occupied by the building, what explains how the building can be visu This is not to be confused with the more controversial claim, criticized by Wu, that these accentuation effects constitute the synchronic phenomenal salience of the attended object. The claim here is only that these accentuation effects are perceptual in nature, a claim even Wu would agree with.

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 Attention-based Perceptualist Theories of Demonstrative Thought

ally selected and demonstratively thought of. We can even appeal to the same sort of subpersonal mechanisms we did before, while still maintaining that it is the subject’s act of conscious attention that sets these mechanisms into play. As a result, the building will be experienced in more detail, and the subject will come to think demonstratively of it. How the notion of synchronic phenomenal salience fits into this picture is another question; no doubt an interesting one, but not something we have to decide at this point. In short, Wu may be right about the effects of conscious attention playing no causal role in grounding demonstrative thought. But it doesn’t follow, from this observation, that acts of conscious attention will not be able to play this role. In the next section I’ll explore in more detail Stazicker’s notion of demonstrative thought, where an interesting picture will emerge: that of demonstrative thought about an object as a form of cognitive attention to that object.

. . Attention to thought )irst of all, it should be noted that Stazicker’s primary goal is not to develop a theory of demonstrative thought per se, but to provide an account of conscious attention. In particular, one that acknowledges the various ways in which it may be realized: both as variations in conscious perception, as the subject attends to various objects in the scene and comes to perceive these objects in more detail, as well as variations in conscious thought, as the subject focuses on different trains of thought that happen to go through her mind. Demonstrative thought comes into the picture as an instance of the latter form of attention, where we focus our thoughts on an object of visual perception. Stazicker borrows the idea of ‘attention to thought’ from Martin, when he writes: What are the most obvious generalizations about attention and thought that form part of the manifest image of these aspects of mind? When I think about the level of subsidy for arable land in the Common Agricultural Policy, I thereby attend to European farming policy. In general, whatever we are prepared to call an object of thought – be it the things thought about, what one thinks about them, or the proposition one thinks in thinking these things – we can also take to be an object of attention. Conscious, active thought is simply a mode of attending to the subject matter of such thoughts. Martin , quoted in Stazicker :

 Recall James’ original definition: “[attention] is the taking possession by the mind, in clear and vivid form, of one out of what seem several simultaneously possible objects or trains of thought James / : , quoted in Wu a: . Emphasis mine .

James Stazicker 

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As this passage suggests, ‘attention to thought’ is not some kind of second-order thought directed at thought itself. Rather, attention to thought is attention to the subject matter of the thought. But if the subject matter of demonstrative thought is an object of visual perception, then it follows from this suggestion that thinking demonstratively of an object is a form of attending to that object – a cognitive form of attention, where one’s thoughts are focused on an object of visual perception and not, for example, on one’s plans for the upcoming weekend . Imagine, for example, that you consciously attend to a particular building and come to think demonstratively of it. At this moment, your thoughts are focused on that building. But after a few minutes you get distracted, and your mind starts wandering to other thoughts: you think about items in your grocery list, about your plans for the upcoming weekend, and so on, only to return to the building after some time. With each shift of attention from one subject matter to another, you come to think thoughts with different contents. This is the sense, emphasized by Stazicker, in which attention also consists in variations of conscious thought. This allows us to say that demonstrative thought about an object is a form of cognitive attention to that object: a form of attention, exercised in thought, to an object of perception. Of course, this proposal needs to be considerably fleshed out before we can properly evaluate it. In the next section I will propose a few different ways to understand it, but for now I would like to address a worry that can be raised against this view. This worry was raised by Jesse Prinz, who is sceptical of the whole idea of ‘attention to thought’. Prinz’s objection is based on the observation that visual attention is something we understand quite well, as it has been investigated for decades using a number of well-established experimental paradigms: visual search and discrimination tasks, spatial pre-cueing, etc. These paradigms provide us with methods to probe into the effects of attention on the way visual stimulus is perceptually processed, as well as on behavioural tasks concerning attended stimuli, with well-established results. We have already seen how pre-cueing a spatial location in the visual field, for example, makes responses directed at stimuli presented in that location faster and more accurate, at the same time that it impairs performance in tasks directed at non-cued locations. We also have a good idea of how to account for these effects at both

 Prinz raised this worry at a Q & A section following Stazicker’s presentation at the Perceptual Attention Workshop held at the University of Antwerp, Belgium, on September st and nd of .

 Attention-based Perceptualist Theories of Demonstrative Thought

the neurophysiological and the behavioural level, as some of the empirical research reviewed in this chapter has already demonstrated. But Prinz’s worry is that if we now say that we can direct our attention not only to visual stimuli but to thoughts as well, to things like European farming policy or the upcoming weekend, this has to be a mere façon de parler. We cannot possibly mean that when I think about whether I should attend a friend’s dinner party this Saturday, I am exercising the same psychological capacity that has been traditionally studied under the guise of ‘attention’ in cognitive psychology. There is simply no clear sense in which the methods, models and theoretical tools deployed in the empirical study of visual attention can be also used to elucidate the notion of ‘attention to thought’. Prinz’s worries are understandable, but the analogy is not so far-fetched as it may sound at first. Indeed, some interesting parallels can be drawn between perceptual and cognitive attention. Take, for example, the phenomenon of semantic priming, where exposure to a word belonging to a certain semantic category will influence later responses to other words, depending on whether they belong to the same/different semantic categories. Suppose, for example, that you are first shown a word like ‘dog’, and are then asked to do a semantic task like finding a word in a list of non-words, or complete a morpheme like ‘wo…’ so as to turn it into a word. Empirical studies have shown that you will be faster to find words in the first task that belong to the same semantic category as ‘dog’, and slower to find words of different semantic categories. And in the second task, you are more likely to form a word like ‘wolf’, which is semantically close to ‘dog’ i.e., they both refer to similar animals , than you are to form a word like ‘world’. 0ow suppose we understand these effects through the notion of ‘attention to thought’, drawing a parallel to the way in which visual attention affects responses directed at attended stimuli. When you read the word ‘dog’, you come to think about dogs you cognitively attend to dogs . As a result, your performance in cognitive tasks involving stimuli that bear close resemblance to dogs like wolves will be improved, at the same time that your performance in cognitive tasks involving stimuli that belong to unrelated semantic categories will be impaired. If spatial pre-cueing is said to ‘highlight’ a region of the visual field, making you respond faster and more accurately to stimuli presented in that region, why not say that inducing a thought about dogs by showing you the word ‘dog’ ‘highlights’ a region in ‘conceptual space’, so to speak? That is to

 Vaidya et al.

, Kolb & Whishaw

.

James Stazicker 

say, that the cue highlights ‘dog’ and makes certain conceptual and semantic connections between dogs and other similar animals salient, thus making you respond faster to stimuli that falls into these neighbouring categories? And we can take the parallel even further. Visually attending to stimuli, as we’ve seen, makes an object be perceived in more detail, as the value of features like contrast, brightness, spatial resolution, etc., are boosted by the allocation of attention. In this sense, visual attention works like a gain-control mechanism, improving the signal-to-noise ratio of stimuli at the attended location so that relevant information can be extracted from it in a more efficient and quicker manner. In a similar vein, we can say that cognitive attention will have an analogous effect concerning semantic processing, allowing the subject to extract conceptual and semantic information from the attended content in a faster and more efficient manner. Attending to the content of a thought, for example, makes it easier for us to assess this content for veridicality, grasp some of the consequences that follow from it, relate it to other contents in neighbouring domains, and so on. It is almost as if, quite literally, the attended content becomes clearer; this is a phenomenon that we philosophers are very familiar with at first sight the claim sounded reasonable, but when I focused on it I came to see that it was flawed . Of course, this is still quite abstract and metaphorical at this point. )urther work would still be needed in order to give more substance to the analogy, but doing so would take us too far off the main topic of this book. My purpose in this brief detour was just to address some of Prinz’s worries, and suggest that the analogy between perceptual and cognitive attention is not so far-fetched as it may seem at first. At the very least, it is an analogy that deserves further examination and that cannot be so quickly dismissed.

. .

Demonstrative thought as cognitive attention

Let’s grant, for the sake of argument, that it would be wrong to understand thoughts about European farming policy or the upcoming weekend as a form of attention to these subject matters. Even so, there may still be a legitimate use of ‘cognitive attention’ in the domain of demonstrative thought, as a type of thought that bears close relations to the psychological notion of perceptual attention. We could say, for example, that demonstrative thought is a form of

 Hillyard et al.

:

.

  Attention-based Perceptualist Theories of Demonstrative Thought ‘cognitive focusing’ on an object of visual perception, something that exploits the same mechanisms of perceptual attention while still being distinct from it. Of course, this proposal still needs to be fleshed out in more detail; what does it mean exactly for one’s thoughts to be ‘focused’ on an object in this way? What is it to cognitively attend to an object of visual perception? In order to address these questions Stazicker considers two possibilities: ‘mode focalization’ or ‘content focalization’. If the former is true, cognitive attention to x consists in you becoming aware of the same content that characterizes your perceptual experience of x, but under a different mode of consciousness: one that is distinctive of thought. If the latter, then cognitive attention to x consists in you becoming aware of a different content, one that is not normally available in perceptual experience and that is made available only when you cognitively focus on the object. It is not clear what it would mean for cognitive attention to be a form of mode focalization. One possibility, following Wu, would be to say that this cognitive mode of consciousness is characterized by an awareness of the attended object as the target of one’s actions. But I have already raised some worries about this proposal section . . : under one construal, this awareness comes with the experience of agency, which is not obviously cognitive in nature; and on another construal, it comes from the experience of thinking, which relies on the highly controversial assumption that there is a sui generis phenomenology of thought. In either case, there’s still a lot of work to be done before this proposal can be properly motivated and taken off the ground. A more promising and less controversial option would be to opt for content focalization. In this picture, cognitive attention would not involve a distinctive mode of consciousness but it would involve conscious awareness of a different content: one that is only available in thought and not in perception. There are three different ways in which this difference in content may be understood: the ‘object view’, the ‘property view’, and the ‘structural view’. I will tackle each of these possibilities in turn. According to the object view, perceptual attention does not make you aware of a singular content, where particular objects are represented. Although you can perceptually attend to things that are in fact objects, the contents you become aware in perception have a general, ‘feature-placing’ structure: ‘apple Stazicker : - . It should be said that although Stazicker briefly considers these two possibilities, he chooses to leave this question open; therefore, all claims concerning mode and content focalization that will be presented in the discussion to follow are my own interpretation, and should not be attributed to Stazicker.

James Stazicker 

ness’, or ‘appleness again’. It is only when you are capable of cognitively attending to objects that you become aware of a singular content, that represents this perceptually presented particular apple. This position is naturally associated with the view I have earlier characterized chapter one as conceptualism about demonstrative thought, according to which singular object representation comes only with substantial conceptual knowledge. The conceptualist would welcome Stazicker’s suggestion of demonstrative thought as cognitive attention, as this would allow her to make sense of the idea that the singular element of these thoughts can only be elucidated by conceptual knowledge brought by cognitive focusing. Clearly, the object-view is not available to the perceptualist. If she wants to cash out the notion of cognitive attention in terms of content focalization, she must look elsewhere. Another option would be the property view, which locates the difference in content in the kind of properties that can figure in the content of either perception or thought. The idea would be that perceptual attention can only make you aware of perceptual properties like colour, shape, size, movement, and so on. Cognitive attention, in contrast makes you aware of further, non-perceptual properties the object may possess, properties whose instantiation you cannot know on the basis of perception alone. But which properties are these? Here are some suggestions. I once read the following advice in a travel guide to Brazil: If you visit the Nossa Senhora do Carmo church in Ouro Preto, pay close attention to the baroque style of its statues. 0ow, ‘being baroque’ is a plausible candidate for being a non-perceptual property, a property whose instantiation I cannot know on the basis of perception alone. In this sense, we might say that ‘being baroque’ is a property of the statue I become aware of only when I cognitively attend to it. Of course, in order to cognitively attend to the statue’s artistic style I must also deploy mechanisms of perceptual attention: I must be able to consciously perceive it and notice some of its surface features – the curves on the statue’s body, the facial expression carved by the artist, and so on. But attending to these features of the statue is not the same as attending to its artistic style. Compare, for example, a tourist who knows that these features are typical of the baroque style, and one who does not. Both are able to perceptually attend to the statue’s shape and facial expression, but only the former knows how to follow the travel guide’s advice and attend to the statue’s baroque style. Therefore, ‘being baroque’ is quite plausibly a property I cannot come to know only in virtue of perceptually attending to the statue and becoming aware of its perceptual features. If attention can make me aware of a content like ‘this statue is baroque’, this can only mean cognitive attention, where I deploy fur-

 Attention-based Perceptualist Theories of Demonstrative Thought

ther cognitive resources to bear in order to recognize certain recognizable features as features that are typically baroque. This, in short, is the property view of content focalization, according to which cognitive attention to an object makes you aware of a different content. Although the object of attention remains constant from perceptual to cognitive attention, the properties that are attributed to it differ in kind. There are, however, some serious difficulties with this view. More specifically with the notion of a ‘non-perceptual property’, something that is notoriously difficult to make precise. One of the most hotly debated topics in the philosophy of perception concerns precisely which properties we can attribute to objects on the basis of perception, and which properties can only be attributed in thought. At one extreme, so-called conservatives claim that only low-level visual features such as colour, shape, movement etc. are properly speaking perceptual properties; at the other extreme, so-called liberals allow properties such as being an object of a certain kind a building, an antique car, a baroque statue to permeate the content of perceptual experience. This makes it difficult to see what it could mean for demonstrative thought to be a form of attention to an object’s ‘non-perceptual properties’. What keeps us from going liberal and saying that properties like ‘being baroque’ can also be represented in the content of perception? Jesse Prinz, for example, has claimed that we directly i.e., noninferentially perceive very abstract properties like the property of being a philosophy major Prinz . According to Prinz, when you ask the philosophy majors in a room full of students to raise their hands and a number of them do, the perceptual state caused by the raised hands represents in that context the property of being a philosophy major. Here’s Prinz: )olk intuitions allow only that we can perceive properties like [being a philosophy major] in an indirect way. It is hardly controversial to say that we can perceive abstract properties by first perceiving something else that indicates that the abstract property has been instantiated, and then representing the abstract property in a subsequent mental episode. On this model, seeing the property of being a philosophy major is very different than seeing red. I want to claim that there is no difference. Seeing red is a matter of having a visual state that represents red. Seeing the property of being a philosophy major is a matter of having a visual state that represents that property. By assigning transient meaning to our visual states, we can literally and directly see the property of being a philosophy major. Prinz :  I borrow the terms ‘liberals’ and ‘conservatives’ from Tim Bayne’s informative discussion on this topic . )or various positions on this debate see the essays in Howley & Macpherson .

James Stazicker 

But if we allow that properties like ‘red’ and properties like ‘being a philosophy major’ can be perceptually represented, we blur the distinction between perceptual and non-perceptual properties. To return to our original example, if visual states can represent a property like ‘being baroque’ we can no longer say that the content ‘this statue is baroque’ is only available to be consciously experienced at the level of thought. Of course, Prinz’s view remains controversial, but it does raise some significant problems to a proponent of the property view. Drawing a distinction between perceptual and non-perceptual properties in a principled way is something notoriously difficult to do, so if we can cash out the notion of cognitive attention without having to do so, this would be preferable. But even if we manage to draw this distinction in one way or another, there is another reason to be suspicious of the property view. The reason is that it is perfectly possible for me to perceptually attend to an object and come to think of one of its perceptual properties, like its colour or its shape. In this case, the content I become aware of in a demonstrative thought like ‘this cube is red’ would not differ from the content I become aware of when I see a red cube, regarding the kind of property that is represented in each case. If I attentively perceive a red cube I am in a position to think of the cube I see that it is red, but this has nothing to do with me becoming aware of a different content, which attributes a different kind of property to the cube. One way to respond to this objection would be to deny that the properties attributed to the cube in perception and thought are of the same kind. Richard Heck, for example, has argued that only thought attributes properties like ‘red’ to a perceived object . )or ‘red’ is a conceptual property that groups together many different shades of red, but this is not how perception represents colours. Rather, perception always represents a maximally determinate shade of red, and never a general property like ‘red’. Bringing in more determinate shade concepts like ‘ruby’ or ‘scarlet’ does not help either: these properties still group together similar shades, which are different from the maximally determinate properties that are attributed in perception. Heck’s suggestion, therefore, points to a way in which the property way could be maintained: perceptually attending to a red cube would make you aware of a content where a maximally determinate shade of red would be attributed to the cube, while cognitive attention would attribute the more general conceptual property ‘red’ to that same object. In conformance with the property view, these are different properties. But this is confused. Saying that perception represents a maximally shade of red does not exclude the possibility that it also represents this shade under a more general perceptual category like ‘red’. Even if it is true that we cannot perceive something red without perceiving it as a more specific shade of red,

 Attention-based Perceptualist Theories of Demonstrative Thought

this is compatible with the claim that ‘red’ can be a genuine perceptual category, and that perception represents something as ‘red’ while simultaneously representing it as a more specific shade of red. Mohan Matthen, for example, has proposed that the function of perceptual systems is precisely to create ordering relations of similarity and dissimilarity among stimuli, which grade the degree of similarity that stimuli bear to one another Matthen : . When we perceive two instances of red of different shades in the same visual scene, we can see that these shades are different from one another, but we can also see that they bear certain similarities i.e., that they are shades of the same colour , which sets them apart from other colours like green or blue that may also be present in the same scene. This is because of the way the visual system represents and classifies colour, in ordering relations that grade the degree of similarity between different stimuli. Therefore, saying that perception represents a maximally determinate shade is not an argument against the claim that it also represents more general colour categories: for according to the sensory ordering thesis this shade is represented in an ordering relation, which groups it together with other shades of red while also differentiating it from shades of blue or green. Moreover, there are obvious epistemological difficulties with Heck’s proposal. )or if we exclude more general perceptual categories like ‘red’ from the content of perception, there will be nothing in common between an experience of seeing a red cube and an experience of seeing a red apple, when these differ only in maximally determinates shade of red: each perceptual experience would represent a different maximally determinate shade, and they would not be represented as bearing some similarity relation to one another. And although Heck is happy to accept this consequence : , this is implausible: if there is nothing in common between these experiences, how could we move from perceiving a series of distinct shades to the application of the more general category ‘red’ that groups these shades together? There would be no perceptual basis for the application of the concept ‘red’, since we do not really perceive things as ‘red’; but this is implausible. If the cube does not really look ‘red’ to me, how could my perception justify the demonstrative judgment ‘this cube is red’? Heck is, of course, well aware of these epistemological difficulties. His solution consists in saying that although perception explicitly represents only max This is one of the main ideas behind Matthen’s ‘sensory ordering thesis’, which he defends at length in his book. See Matthen : for a clear statement of this thesis, which emphasizes the point raised in the present discussion.

James Stazicker 



imally determinate shades of red, it nevertheless implicitly represents shades of red as ‘red’. So even if there are no similarities between the experiences of the red cube and the red apple regarding their explicit content, there is nevertheless a similarity in their implicit content: this is what allows us to subsume these experiences under a more general category like ‘red’, and which explains how experience can justify our demonstrative judgments that attribute ‘red’ to objects that look to be so. But what exactly does it mean for perception to implicitly represent a property like ‘red’? Heck attempts to clarify this point by appealing to the implicit/explicit distinction as it has been traditionally applied to beliefs. To illustrate with an example, suppose that I believe I am less than two meters tall. If this is something I believe, then I also believe that I am less than three meters tall, that I am less than four meters tall, and so on. But of course, only the first belief is explicitly represented in my ‘belief box’, so to speak. The others are only implicit beliefs, in the sense that they can be inferred from explicit beliefs via a short enough chain of reasonably obvious inferences , as Heck puts it : . But regardless of the merits of this distinction when it comes to beliefs, it is far from clear how to understand it in the case of perception. In our example above of ‘being less than two meters tall’, we can easily account for my capacity to infer the implicit beliefs from the explicit one in terms of logical relations between contents. ‘Being less than two meters tall’ entails ‘being less than three meters tall’ which entails ‘being less than four meters tall’ and so on. So if I as a rational agent self-ascribe the first property, I should normally be able to draw the relevant inferences. But what does it mean to say that the more general category ‘red’ is inferred from a representation of a more specific shade of red? Heck does not really elaborate on this. Perhaps what this means is that perception represents a maximally shade of brown within a certain scale of similarity, that groups it together alongside other shades of brown. So although perception explicitly represents only a maximally determinate shade, its similarity to other shades would be implicitly represented by its ‘position’ in a certain quality space. If I simultaneously perceive red and red , my perception would represent each of these shades differently but placed next to one another in a sensory quality space. This would allow me to grasp that they are similar to one another, although this is not something perception explicitly represents. This proposal still needs to be fleshed out in more detail, but at this point we risk turning it into a purely terminological dispute. It’s not clear how different this view would be from Matthen’s claim that perception simultaneously represents ‘red’ and a maximally determinate shade of red, i.e., that there is a

 Attention-based Perceptualist Theories of Demonstrative Thought

certain hierarchy in the way visual systems classify and represent visual stimuli. In addition, this proposal does not really help the property view of content focalization. Once we grant that perception represents a shade of red within a quality space next to other shades of red i.e., that it implicitly represents this relation of similarity , the claim that I cannot become aware of a more general property like ‘red’ on the basis of perceptual attention loses much of its force. If I simultaneously perceive two different shades of red and see that they’re similar, haven’t I become perceptually aware of a more general property, one that applies to both shades I experience? But perhaps what Heck has in mind is not so much what is suggested by the property view, but rather what we may call the ‘structural view’ of content focalization. This is the view according to which cognitive attention to O consists in you becoming aware of a content with a different structure – one with conceptual structure, as opposed to the nonconceptual structure of perceptual content. In this picture, although the attended object and property would remain constant from perceptual to cognitive attention, they would be represented in different ways, i.e., in terms of a different kind of content. One way to cash out this suggestion, following Peacocke, is to say that perception represents the world with a spatial, image-like scenario content, while thought consists in relations to structured )regean propositions Peacocke : ff . When we come to think of it, this is the most plausible option for an attention-based perceptualist to pursue. It allows her to give substance to the claim that it is perception what explains our capacity to have demonstrative thoughts about objects in our external environment, while also having something substantial to say about what thinking demonstratively of an object consists in. Having in mind the material discussed so far in this chapter, we can now propose the following picture of attentional perception and demonstrative thought: Perception explains our capacity for demonstrative thoughts in virtue of the psychological notion of conscious attention. As Stazicker suggests, particular acts of conscious attention function as the natural analogs of demonstratives at the level of perception, by ‘directly’ i.e., with no representational intermediaries selecting objects in the world and making these objects available to be consciously experienced. These acts of conscious attention will have two effects: the attended object will be perceived in more detail, and the subject will cognitively attend to it. When she does so, she will become aware of a different con There are also other ways of cashing out the conceptual/non-conceptual distinction, but we need not go into details at this point. See the essays in Gunther for different proposals along these lines.

James Stazicker 

tent – with conceptual structure – that represents the same objects and properties that were nonconceptually represented in perception. This conceptual content is characteristic of demonstrative thought, and marks the difference between perceptual and cognitive attention. But as perceptualism insists, it is only in virtue of being in a perceptual state with a singular nonconceptual content that the subject is able to cognitively attend to the object represented in that content, i.e., have a demonstrative thought about it. Therefore, the main idea of perceptualism can still be maintained in this picture. We’ve already seen how conceptualism will call into question the main tenets of this theory. At the level of perception, the conceptualist will say, there is no singular content, not even a nonconceptual one. We can only be in mental states with singular contents when we are able to bring some more sophisticated background conceptual abilities to bear in the content of perception. This objection will be spelled out in more detail in chapter five. Before that, however, I would like to consider a different kind of objection to the attention-based model I’ve sketched above. According to this objection, while a form of perceptualism must be true of demonstrative thought, it cannot be an attention-based model. The reason is that attention operates on object representations, which of course presupposes that objects have already been selected pre-attentively. So if perceptualism wants to maintain the overall project of explaining demonstrative thought in terms of demonstrative-like selection mechanisms that pick out objects in the world directly, an attention-based theory cannot be right. We must look to an earlier level of perceptual processing, where objects are first singled out by our perceptual systems in conceptually unmediated ways. It is these mechanisms what ultimately explains how perception supplies us with the objects of our demonstrative thoughts. Spelling out some proposals along these lines will be the main subject matter of chapter four.

0on-attentional Perceptualist Theories of Demonstrative Thought .

Joseph Levine

. .

Intentionally mediated vs. direct meta-semantic mechanisms

Let’s start by making a distinction, suggested by Levine, between ‘intentionally mediated mechanisms’ IMM’s and ‘direct meta-semantic mechanisms’ DMM’s . IMM’s are defined by Levine as any kind of reference-fixing mechanism that refers through the semantic content of another representation, while DMM’s pick out their referents directly, by which he means ‘without any sort of representational intermediaries whatsoever’ Levine : - . A paradigmatic example of an IMM would be a descriptive name like Evans’ ‘Julius’, which picks out an individual in virtue of this individual satisfying the description ‘being the inventor of the zipper’ Evans : . But although being descriptive is a sufficient condition for a reference-fixing mechanism to be an IMM, it is not necessary. Ordinary proper names like ‘Aristotle’ are also IMM’s in Levine’s definition, even if they do not refer in virtue of some descriptive material associated with the name. )or if some version of the causal theory of names is correct and the name refers in virtue of a causal chain of uses leading back to an initial baptism, then ‘Aristotle’ secures its reference through the content of another representation – namely, through the demonstrative representation ‘this baby is called Aristotle’, involved in the initial baptism which endowed an individual with that name Levine : . With this terminology in hands, Levine makes the point that when we refer to an object in thought with a demonstrative like ‘that building’, this act of mental demonstration cannot be a DMM; after all, in order to mentally demonstrate the building one must first perceive it, so plausibly mental demonstratives secure their referents through the content of perceptual representations. So if we want to know how mental demonstratives can refer to objects in the world, we must ask, in turn, how visual perception selects objects in the world. What in perception can play the role of a DMM? According to the attention-based perceptualist theory sketched in chapter , conscious attention plays this role. More specifically, particular acts of conscious attention, as they set subpersonal mechanisms into play that will select objects in the world and make these objects available to be consciously experienced and thought about. Levine, however, argues that conscious attention cannot be a DMM.

Joseph Levine 

Levine’s first argument against attention as a DMM stems from his commitment to a computational-representational theory of mind CRTM . That is to say, if mental processes and operations are functionally defined over mental representations, as they are in CRTM, then it follows that attention, as a type of mental operation, must take as its immediate operand a mental representation: it cannot operate on external objects directly. )or a mental operation like ‘attend to [x]’ to be executed, the value of ‘x’ must be specified, and if follows from CRTM that ‘x’ must be a mental representation. Therefore, conscious attention cannot be a DMM. It must presuppose that objects have already been perceptually selected and represented in the visual system. This argument, however, begs the question. What’s at stake is precisely whether conscious attention must presuppose a prior object representation, or if conscious attention is the cause of object selection in the first place. If the former, then indeed conscious attention must take the form of something like ‘attention to [x]’, where ‘x’ stands for a perceptual representation of an object. But this is not something one can assume from the outset. The attention-based perceptualist is putting forward a causal hypothesis to the effect that conscious attention is the cause of object selection, which is an empirical claim. This is not something that can be decided on a priori grounds, by the theoretical requirements of one’s preferred theory of the mind. It is an object of empirical investigation. We can make this point clearer by making an analogy with two security guards equipped with a spotlight, whose duty is to watch prisoners from a watchtower during the night. The first guard is given a map with the exact locations of each prisoner’s cell, which allows him to focus the spotlight on a particular cell, turn it off, shift it to the location of another cell, turn it back on, and so on. The second guard, however, is given no information about the cells’ locations. Therefore, he must scan the prison with the spotlight until a prisoner’s cell is found, check on this prisoner, and then continue with the spotlight until the next cell is located. Although the second guard is also able to select prisoners with the spotlight, it doesn’t follow, from this general capacity, that he must already have a map of the prison that represents the locations where the spotlight will be directed. Even in the absence of a map, there are different strategies he could use in order to select prisoners with the spotlight. He can, for example, search for signs of movement or shadows at certain locations, which may be reliable indicators of prisoners in those locations. This does not require

 See Levine

:

. The locus classicus of the CRTM is )odor

.

  0on-attentional Perceptualist Theories of Demonstrative Thought that prisoners must already be represented in a map for the spotlight to be directed at them. On the contrary, in this second strategy the spotlight itself is the cause of prisoner representation . Which of these analogies best captures the role of attention in object selection is an empirical question, that cannot be decided on purely a priori grounds. There is one kind of empirical study that may allow us to settle this issue. It is a well-established fact in cognitive psychology that the sudden appearance of a new object in the scene automatically attracts attention to this object. In order to account for automatic attentional capture by abrupt object onsets, Steven Yantis has put forward two different hypotheses: according to the ‘luminanceincrement explanation’, low-level visual processes detects luminance increments caused by an abrupt onset of a new object in the scene, and automatically directs attention to the region of the visual field where the luminance increment is detected. In contrast, the ‘new-object explanation’ claims that as soon as a new object appears in the scene, a perceptual representation is automatically and pre-attentively created for it, prompting the visual system to automatically direct attention to the new object in order to assess it for behavioural significance Yantis : . If the luminance-increment hypothesis turns out to be true, it would imply that attention can operate without a prior object representation. The value of ‘x’ in an operation like ‘attention to [x]’ would be a region of the visual field where a certain luminance increment was detected, and not an object representation. Once attention is spatially allocated to the relevant region, the object in that region would be selected by the subpersonal mechanisms posited by the attention-based perceptualist chapter , section . . , making her causal hypothesis true. This suggests that we need to be careful with the IMM/DMM distinction and the whole idea of ‘direct’ mechanisms of visual selection. As Levine formulates it, a DMM is a reference-fixing mechanism that selects objects in the world without any sort of representational intermediaries whatsoever. In this sense, perhaps it is true that conscious attention is not a DMM. )or even if the luminanceincrement hypothesis turns out to be true, attention would still secure its referent through a perceptual representation – namely, a representation of a luminance increment. But as long as conscious attention does not operate on object representations, it could still be described as a mechanism that selects objects in the world directly, in the sense that it does not presuppose that objects have already been selected and represented in the visual system. In other words, attentional processing would still be the lowest level in the hierarchy of visual processing where objects would be represented, over and above luminance

Joseph Levine 

increments. Therefore, what matters for the present discussion is not so much whether representational intermediaries are involved in visual selection, but whether object representations are. In order to capture these observations we could modify Levine’s original definition of DMM’s in the following way: Perceptual DMM: a perceptual mechanism P selects objects in the world ‘directly’ iff P is the lowest-level mechanism that explains how objects are represented in the visual system.

If Yantis’ luminance increment hypothesis is true, then attention could be a perceptual DMM in the sense above, even if it selects objects in the world through some representational intermediaries, namely, representations of luminance increments in certain regions of space. But this does not mean that this mechanism is any less ‘direct’, or that we have severed the connection between mind and world. After all, the luminance increments that guide the allocation of attention in this hypothesis are reliably caused by the presence of external objects in the visual field, and it makes sense to suppose that our visual system has evolved to be causally sensitive to the luminance increments that reliably indicate objects. But as long as attentional processing is the lowest-level mechanism that explains how objects are represented in the visual system, it could still be considered as the cause of object selection. So if one wants to argue against attention-based perceptualism on empirical grounds, one would have to argue against the luminance increment hypothesis. But here it seems that the non-attentional perceptualist has an advantage: the empirical evidence from abrupt object onsets speaks against this hypothesis, and in favour of the new-object explanation. In a paradigmatic abrupt onset experiment, subjects are instructed to search for a certain target letter in a visual display. They are first presented with a set of figure-eight placeholders for two seconds, followed by a display of letters where the target is to be found. An abrupt onset stimulus is one that appears in a previous blank location, such as the ‘E’ in figure below. Yantis & Hillstrom have found that subjects are faster to detect the target when it matches the abrupt onset stimulus, and that reaction time does not increase with display set size in contrast with a control condition where the target letter is presented in the location of one of the figureeight placeholders . This provides strong evidence that attention is automatically captured by abrupt onsets.

 0on-attentional Perceptualist Theories of Demonstrative Thought

)ig. 9: Experimental design for automatic attentional capture by abrupt object onsets from Yantis 99

According to the luminance increment hypothesis, this is to be explained in terms of low-level mechanisms that detect luminance increments caused by abrupt onsets, causing attention to be directed to the region of the visual field where the luminance increment was detected. So if no luminance increment were detected, the prediction would be that no automatic attentional capture should occur either. This is not, however, what Yantis & Hillstrom have found . Using stimuli whose mean luminance was equal to the background, they have found the exact same results as in paradigmatic abrupt onset experiments, with subjects detecting targets faster when it matched the abrupt onset stimulus, and where reaction time does not increase with display set size. This provides strong evidence that attention is automatically captured by the sudden appearance of a new object in the scene, regardless of whether it is accompanied by a change in luminance or not. Therefore, it cannot be detection of luminance increment what is driving the allocation of attention to the new object. The alternative, suggested by Yantis , is that the sudden appearance of a new object in the scene automatically causes the visual system to perceptually and pre-attentively represent the new object, prompting attention to be directed towards it for the purposes of assessment for behavioural relevance. This corroborates Levine’s claim that

 Besides luminance, similar abrupt onset experiments have also been run with features like brightness, motion and colour, with the same results: that is to say, abrupt onsets automatically capture attention even if they are not accompanied by changes in brightness, motion, colour or luminance Yantis .

Joseph Levine 

conscious attention cannot be a mechanism of object selection, since it already presupposes some form of pre-attentive representations of objects. So if objects must already be represented in the visual system for attention to be directed towards them, what kind of pre-attentive mechanism can play the role of a DMM in perception? The best candidate for filling this role, according to Levine, is Pylyshyn’s )I0ST mechanism / , which is posited as a nonconceptual and pre-attentive mechanism of object selection. Pylyshyn’s hypothesis is that our visual system has around four indices available – or )I0ST’s – which can be simultaneously assigned to four distinct objects in the world, allowing us to individuate and maintain the numerical identity of these objects independently of the allocation of attention.

. . Multiple object tracking and pre-attentive object representations Pylyshyn’s first reason for postulating )I0ST’s stems from the need for something to provide the initial point of contact between mind and world, a referential relation that does not presuppose a prior capacity to represent or make reference to objects, but on the contrary, can be used to explain it. Pylyshyn’s hypothesis is that what explains visual reference and object representation is the )I0ST mechanism in the early vision system. This mechanism has been shaped by evolutionary processes to be causally sensitive to certain clusters of features in the world, as these clusters tend to correspond, in the kind of environment where our visual system has evolved, to ordinary material objects. According to the )I0ST hypothesis whenever we are confronted with a visual scene our visual system will automatically and simultaneously assign visual indices to up to four of these clusters, allowing us to individuate and maintain their numerical identity in time. As this index assignment is done automatically and pre-attentively, this falsifies the attention-based perceptualist’s causal claim. Conscious attention can no longer be the cause of object selection because it presupposes that objects have already been selected and perceptually represented in early vision through indexing mechanisms.

 )I0ST stands for ‘)ingers of I0STantiation’, to stress the analogy with pointing fingers that allow one to refer and keep track of objects without having to encode the properties of what is being pointed at see Pylyshyn : . The ‘early vision system’ is functionally defined as the part of the visual system which is ‘cognitively impenetrable’, i.e., encapsulated from beliefs, expectations, and other higher cognitive processes see Pylyshyn .

 0on-attentional Perceptualist Theories of Demonstrative Thought

In addition, Pylyshyn argues that )I0ST’s are needed to explain empirical data from object individuation and tracking tasks. The most important evidence comes from the Multiple Object Tracking MOT experimental paradigm. )or if Pylyshyn is right and the visual system has its own means of individuating and keeping track of up to four visual units independently of the allocation of attention, then it predicts that something like multiple object tracking should be possible, even in conditions where one cannot allocate attention to each individual object to be tracked. In a typical MOT experiment like the one illustrated in figure below, subjects are instructed to keep track of four targets moving randomly among qualitatively identical non-targets. At t targets are identified by a cue that initially distinguishes them, such as blinking on and off once before the experiment begins. After the targets move for some time across the display t , subjects are asked to report at t whether the indicated stimulus is a target or a non-target. These experiments have been widely replicated in different laboratories, and the evidence shows that subjects are quite good in tracking up to four of these targets, with a success rate of about % Pylyshyn : . This success rate is maintained even if targets are occasionally overlapped by non-targets, disappear behind obstacles, or change some of their surface features like colour or shape . After five targets, however, performance drops drastically, something that fits very well with Pylyshyn’s hypothesis about the set-size limitations of the )I0ST mechanism.

)ig.

: Experimental design for Multiple-Object-Tracking from Pylyshyn & Annan

6.

But here one may object; sure, the evidence clearly shows that we can keep track of up to four objects at the same time, but why should we suppose that the  Pylyshyn & Storm

, Dennis & Pylyshyn

, Bahrami

.

Joseph Levine 

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visual mechanisms that explain MOT must be pre-attentive? After all, phenomenologically speaking it certainly feels as if attention is being recruited in a MOT task. There is a clear feeling of effort and concentration in carrying out the task, which are distinctive of attentional engagement. )urther on, it has also been shown that tracking performance decays in time as tracking periods grow longer, something that shouldn’t happen if tracking is being done automatically and pre-attentively Oksama & Hyönä . Pylyshyn, however, argues against an attentional explanation of MOT on the following grounds: as targets and non-targets spatially overlap, one could not keep track of them with a single attentional spotlight, as this would fail to distinguish between targets and non-targets. The next best attentional strategy, according to Pylyshyn, would be to serially shift attention to each target so as to encode their locations. Then as targets move around the screen, one would quickly revisit each encoded location, move the spotlight to the object that is closest to it, update the location of the object to this new location, and so on successively for each target until the end of the task. But even with a very conservative estimation about the time-scales of these successive attentional shifts, computer simulations have shown that this strategy would yield a much, much poorer performance than what is actually observed in MOT. Moreover, this strategy is also phenomenologically inadequate. As argued at length in chapter three specially section . . , when one consciously directs one’s attention to an object, one is typically aware of doing so. But when we are engaged in a MOT task, we are not aware of allocating attention to each target in a serial manner. On the contrary, as soon as we try to focus on a particular target, we lose track of the others targets. But what explains the feeling of effort and concentration that is characteristic of attentional engagement and which is also present in MOT tasks? According to Pylyshyn, the feeling of attentional effort does not come from the MOT task itself but from an ‘error recovery stage’, where one attempts to recover a target which has been temporarily lost Sears & Pylyshyn , or to the effort of shunning off other competing tasks and events so that one can be fully engaged in the MOT task Pylyshyn et al. . This allows Pylyshyn to maintain that our capacity for MOT is to be explained at the pre-attentive level, while the feeling of effort that accompanies it is attributed to other cognitive processes.  The reader is invited to try the task for herself in order to feel this effect. Online video demonstrations can be found at http://ruccs.rutgers.edu/faculty/pylyshyn/DemoPage.html More precisely, a % success rate according to Pylyshyn : - . Again, the reader is invited to try this for herself see fn. .

 0on-attentional Perceptualist Theories of Demonstrative Thought

So if we assume for the moment that )I0ST’S can play the role of a preattentive mechanism of object selection, how could we incorporate it into a perceptualist theory? The attention-based theory sketched in the previous chapter gave us three levels to look at: first, there is the distal object itself. This object is selected by some subpersonal mechanisms set into motion by conscious perceptual attention, yielding a level of perceptual representation that is more primitive than thought about the object. In addition, there is a further act of cognitive attention that exploits mechanisms of perceptual attention but makes the subject aware of a new kind of content, with conceptual structure. This is what allows one to think conceptually structured thoughts about external objects, thoughts of the form ‘this is )’. In Levine’s non-attentional model, however, we must acknowledge one additional level, even more primitive than the level of conscious attentional perception. This level, corresponding to )I0ST representations , accounts for how visual perception selects objects in the world in a direct manner, through an indexing mechanism that is causally sensitive to certain clusters of features in the world that tend to correspond, in the kind of world we live in, to ordinary material objects . At the level above it, attentional mechanisms select a subset of these visual indices for further processing, allowing the subject to perceive them in more detail and have faster and more accurate behavioural responses in relation to them. At the highest level we have a further cognitive operation that selects an object of perceptual attention to be a constituent of a conceptually structured thought of the form ‘this x is )’. The demonstrative ‘this x ’ inherits its singular content from the content of the underlying attentive representation, which in turn inherits its content from the underlying visual index Levine : - . The difference between the two models can be captured in the figure below:

 There is a disagreement between Pylyshyn and Levine on whether )I0ST’s qualify as perceptual representations or not; Levine thinks they do, while Pylyshyn argues they merely point to objects in the world without representing them. This debate, however, is largely terminological, and has no bearing on the present discussion.

Joseph Levine 

)ig.

: Contrast between attention-based and non-attentional perceptualism

In this picture, although there is still an important role for attention to play in the theory, it is no longer as a mechanism of object selection. Attention is now a selection operation that mediates between the pre-attentive level of index assignment and the higher cognitive level of demonstrative thought. This is still compatible with an idea sketched in chapter three, according to which demonstrative thought may be understood as a form of cognitive attention to an object of perception: cognitive attention would select an object of conscious attentional perception and make it available to be part of a conceptually structured thought. The crucial difference between the two models is that what explains how perception selects and represents objects in the world is not an attentional mechanism but a pre-attentive one, namely, Pylyshyn’s )I0ST mechanism. We’ve already seen that the main reason why )I0ST’s are supposed to be pre-attentive is that the experimental results from MOT cannot be explained in an attentional model. In the next section, however, I would like to consider further evidence and alternative explanations of these results, which will call into question whether the evidence really speaks in favour of )I0ST’s as a preattentive mechanism.

. .

An attentional account of multiple object tracking

Pylyshyn has already argued that subjects’ performances in MOT tasks cannot be explained in a traditional ‘spotlight’ model of attention. )or either the spotlight is focused over a larger region of the visual field in order to encompass all targets at once, but then fails to distinguish targets from non-targets, or it is narrowed down in order to focus serially on one target at a time, yielding a highcost and error-prone strategy that could not possibly account for the % success rate routinely observed in MOT.

 0on-attentional Perceptualist Theories of Demonstrative Thought

But although these observations effectively rule out these kinds of attentional strategies, they do not establish the existence of a pre-attentive mechanism. )or once, there is now empirical evidence that attention does not have to work like a single spotlight but can be simultaneously divided among multiple foci Cavanagh & Alvarez , Rensink . Using Posner’s classical spatial cueing paradigm, Awh & Pashler have shown that simultaneously cueing multiple regions of the visual field yields attentional benefits for all cued regions, with no benefits at regions between cues. These results cannot be explained in a single spotlight model, as it would predict attentional benefits at regions between cues as well. At the neurophysiological level, imaging studies from McMains & Somers have also shown separate peaks of activation in striate and extrastriate cortices that correspond to multiple attended regions of the visual field. In addition, there is also evidence of signature marks of object-based attention in MOT tasks. One of the main findings of object-based attention is that when attention is directed to a part of an object it ‘spreads’ uniformly to cover the entire surface of the object, yielding attentional benefits for stimuli presented anywhere within the object’s boundaries. Cueing the bottom part of an object, for example, diminishes reaction time directed at stimuli at the top part of the same object, but increases reaction time directed at stimuli presented in a different object. This is so even if both stimuli are equidistant to the initial cued location Scholl et al. . Similar results have also been found in MOT tasks. When target and nontarget pairs are conjoined by a line, Scholl et al. have found that tracking performance is severely impaired, even if targets and non-targets move in the exact same trajectory as a control condition without the conjoining lines and where performance is normal . This impairment can be easily explained if we assume that MOT involves object-based attention. In the conjoined condition, the target/non-target pair is being treated by the visual system as a single object, so when attention is allocated to a target, attention spreads uniformly to cover the entire ‘object’, causing observers to lose which is the target and which is the distractor. These observations allow us to propose an alternative account of MOT on the basis of multifocal attention, where each target attracts an independent focus of attention that follows it as it moves, thus explaining subject’s good performances in MOT. This is exactly what Cavanagh & Alvarez have proposed. In their model each target is simultaneously tracked by an individual focus of attention, guided by a control process that keeps selection centred over targets as they move. These processes are then supplemented by an encoding

Joseph Levine 

stream that takes information from the targets and passes it on to higher cognitive processes, which control subjects’ verbal responses at the end of the task. So instead of the set-size limitations in MOT tasks being explained by the number of indices available in the early vision system, in a multifocal attentional model the number of items one can track is constrained by working memory limitations, which can only deal effectively with around four items at a time Kahneman et al. . There’s nothing in the MOT results that forces us to seek a pre-attentive explanation of the phenomenon. )inally, there is also a striking feature of MOT tasks that seems to be a problem for the )I0ST theory. Typically, after the end of a MOT task subjects are remarkably good at indicating whether a certain element is a target or a nontarget, with a success rate of over %. However, subjects are generally quite bad in indicating which particular target that is. That is to say, if before the beginning of the task you mentally label each target to be tracked with the letters ‘A’, ‘B’, C’ and ‘D’, at the end of the task you may accurately and confidently indicate whether an indicated item is a target or a non-target, but you would be unable to tell whether this target is ‘A’, ‘B’, ‘C’ or ‘D’, or whether this target identified at the end of the task is identical to that target which started out at the top-right corner of the screen . But if performance in MOT is explained by the automatic deployment of visual indices to each target to be tracked, this is a surprising result. After all, one of the main motivations for positing visual indices is to endow the visual system with a capacity to automatically individuate and keep track of particular objects, where each object is individuated by a numerically distinct index automatically assigned to it. That is why Pylyshyn compares )I0STS to fingers that point to particular objects, where the pointing finger is supposed to provide the visual system with an address it can use in order to direct attention to these objects. This is especially clear in the passage below, where Pylyshyn draws the analogy between )I0ST’s and ‘pointing fingers’: It seemed to me that the superhero [Plastic Man] had what we needed to solve the identitytracking or reidentification problem. Plastic Man would have been able to place a finger on each of the salient objects … . Then no matter where he focused his attention … Plastic Man would still be able to think this finger and that finger and thus be able to refer to individual things that his fingers were touching. Pylyshyn :

 See Scholl

for discussion.

  0on-attentional Perceptualist Theories of Demonstrative Thought But if you are simultaneously tracking one object with your index finger and another object with your middle finger, you should not have any problem in telling, at the end of the tracking period, which one is which: each finger provides an unique address for each tracked object, which gives you means to know that ‘this one’ at the end of your index finger is different from ‘that one’ at the end of your middle finger , at any point during the tracking period. But now it seems that, on the contrary, this indexing mechanism is constantly swapping targets among one another. It is still successfully maintaining the identity of targets as a set, but not the identity of individual targets. This weakens considerably the whole purpose of having individual indices in the first place. A more apt analogy would be that of a ‘closed hand’, which holds objects together and enables one to distinguish targets the ones inside the hand from non-targets the ones outside it , but not individual targets from one another. This is exactly Ronald Rensink’s proposal in his coherence theory of attention, where attention functions like a hand that grabs a small number of proto objects – around four – and allows the subject to keep track of their spatial trajectory in time Rensink . Rensink even suggests that in the contexts of MOT tasks we should replace Pylyshyn’s ‘)I0ST’s’ with the more apt term ‘HA0ST’, to capture the way attention holds four items together as a set, and not as four individual items which one can independently refer to Rensink : fn . This model also allows us to explain Pylyshyn’s results without resort to pre-attentive tracking mechanisms. In the same spirit, Scholl proposes a set-based attentional model in order to account for MOT results, where attention is allocated to the targets to be tracked as a set. The allocation of attention enhances perceptual processing of members of the set throughout the duration of the trial, allowing one to successfully track the set and identify elements as members or non-members of the set. As the attended set as a whole benefits from enhanced processing due to the allocation of attention, this accounts for subject’s good performance in MOT tasks. But insofar as attention is being directed to the set as a whole, individual members would not be differentiated from one another, thus explaining subject’s inability to tell which one is which at the end of the trial. So it seems that the ‘HA0ST’ model or the set-based attentional model are able to account for the same data as the )I0ST model, and, in addition, explain additional data that the )I0ST model has trouble accommodating. Moreover, it also makes fewer assumptions than the )I0ST model. After all, )I0ST posits a mechanism of pre-attentive tracking for which we have no other independent evidence, while the set-attentional model simply builds on well-established facts about working memory and the benefits of attention on attended stimuli.

Joseph Levine 

Of course, many details of this model would still need to be fleshed out, but it is not my purpose here to defend this model against Pylyshyn’s. The purpose of this section was just to show that it is not clear that evidence from multiple object tracking establishes the existence of a pre-attentive indexing mechanism. The only reason we are led to a pre-attentive account of the phenomenon comes from the inability of traditional single spotlight models to explain the data, but we have seen that there are other attentional models that can explain the data equally well. As nothing in an attention-based perceptualist theory requires commitment to single spotlight models, evidence from MOT tasks does not take the attention-based perceptualist out of the game yet. All evidence presented so far is compatible with the thesis that conscious attention is the cause of object selection and tracking. MOT would just be a special case where attention selects more than one object at a time.

. .

The evidence from subitizing

Another type of evidence that supporters of )I0ST theory often appeal to comes from subitizing, a process for estimating numerosity which is usually taken to be fundamentally different from counting. Subitizing occurs when the items to be enumerated are less than four, in which case one will be able to tell immediately, accurately and with a high degree of confidence how many items there are. If, however, the items to be enumerated are more than four, the process of recognizing their numerosity is slower, effortful, and error-prone, as one must serially count each individual item to be enumerated. Although different models have been proposed in the literature in order to account for the mechanisms underlying these two processes, one popular explanation is that subitizing recruits pre-attentive processes of object individuation, while counting requires serial attentional processing. One important motivation for explaining subitizing in terms of pre-attentive processes comes from its effortlessness, accuracy and immediacy, which are usually taken to be signature marks of pre-attentive processing. Recall Treisman’s visual search tasks we have reviewed in chapter section . . : no matter how many distractor items are added to the search display, targets that differ from distractors in one single dimension immediately ‘pop out’, and the search task is effortless, immediate and accurate. If, in contrast, the target is defined by  )or a useful review of different models of subitizing and counting see Dehaene & Cohen .

 0on-attentional Perceptualist Theories of Demonstrative Thought

conjunction of features, search is slower and effortful. This is usually explained by the fact that binding features together requires focal attention, while detection of single features occurs pre-attentively and in parallel Treisman . In a similar vein, Trick & Pylyshyn have found that subjects are capable of subitizing single-feature targets in a display with up to twenty distractors, while no evidence for subitizing was found for targets defined by conjunctions of features presented among a number of distractors. This evidence links subitizing to pre-attentive processing. In addition, if subitizing were a serial attentive process, as we increase the number of items to be enumerated we should expect there to be a linear increase in estimation time. Enumerating two items should take longer than one, three should take longer than two, and so on. This is not, however, what is routinely observed in these tasks. 0umerous studies have consistently found that there is little increase in estimation time until the number of items to be estimated reaches four. After that, there is a steep increase in estimation time, forming an elbow in the graph curve at around four items fig. .

)ig. : Relation between reaction time and errors in estimations of numerosity from Dehaene & Cohen 994 .

In order to explain this pattern, Trick and Pylyshyn argue that there must be some pre-attentive mechanism of individuation that is recruited by the subitizing process. As the subitizing range coincides with the number of available

 See Trick & Pylyshyn

, Dehaene & Cohen

.

Joseph Levine 

)I0ST’s four , Pylyshyn’s indexing mechanism provides an excellent candidate for the pre-attentive mechanism in question. When the number of items to be enumerated is equal to or lower than the number of available )I0ST’s, subitizing occurs; one knows immediately, confidently and accurately how many items there are. If, however, the number of items exceeds the number of )I0ST’s, serial attentional processes must be recruited, and counting begins. This hypothesis is consistent with the data, and accounts for the elbow curve found in subitizing studies. But notice that one more time, attentional explanations of subitizing are ruled out only if we assume a single spotlight model of attention, that must move to each item to be enumerated in a serial manner. Indeed, when Trick & Pylyshyn criticize attentional explanations of subitizing, this is exactly what they have in mind: although ‘attention’ has come to mean different things, they write, when we refer to attention we are simply referring to analyses that occur one location at a time Trick & Pylyshyn : . Granted, the subitizing data cannot be explained in this model, but we have just seen that there are alternative ways to conceive of attentional selection. It seems, for example, that the data could be explained equally well in a multifocal attentional model, much like the one we’ve briefly sketched in the previous section: a mechanism that allows attention to be simultaneously deployed to multiple locations or objects in the visual field, with a set-size limit of about four which corresponds to working memory limitations . In this picture, subitizing and counting would both be attentional processes, but with an important difference: subitizing recruits multifocal attention, while counting involves serial deployment of attentional selection. This explains why subitizing is fast for a number of items equal to or lower than four. After that, this mechanism can no longer be deployed and serial focusing takes over, explaining the elbow curve obtained from subitizing studies. Moreover, there seems to be empirical evidence that speaks in favour of an attentional model of subitizing. Using the ‘attentional blink’ experimental paradigm, Egeth et al. and Olivers & Watson have independently found evidence that when a subitizing task is immediately preceded by an attentional task such as a letter identification in a visual display , the subitizing task is negatively affected. An ‘attentional blink’ arises when subjects are required to perform two attentional tasks A and B immediately after one another, with an observed negative effect on B. This is usually explained by the fact that attention is still involved in processing task A when task B comes up Egeth et al. : .

 0on-attentional Perceptualist Theories of Demonstrative Thought

But the fact that a subitizing task can be negatively affected by an immediately preceding attentional task is not itself surprising. After all, subitizing itself is a cognitive task, involving not only the individuation of items but a judgment of their numerosity: we usually don’t go around enumerating every group of four items or less we encounter in the world. As such, the negative effect could be traced to the post-perceptual stage of judging how many items there are in the display. But if this were the case, we should expect only general task impairments explained by dual-task constraints, and the observed negative effects should be the same throughout the whole subitizing range. If the attentional blink affects only post-perceptual judgments of numerosity, we should not expect these negative effects to differ within the subitizing range. This is not, however, what the evidence shows. Egeth et al. and Olivers & Watson have found a progressive increase in estimation time during the attentional blink, even for numbers within the subitizing range. Enumeration of one single item was not affected by the attentional blink, but enumeration of as few as two items was already impaired if immediately preceded by an attentional task, with estimation time rising progressively for three and four items. But if subitizing relied on the automatic assignment of )I0ST’s in the early vision system, this should not occur. We should at most expect some general interference due to dual-task constraints, but this should affect the subitizing range in a uniform manner: we shouldn’t see a progressive increase in estimation time from two items onwards, which is what was observed. To conclude, it is not clear that data from subitizing studies demonstrate the existence of the pre-attentive indexing mechanism posited by Pylyshyn. Although this hypothesis is consistent with the elbow curve obtained from subitizing studies, it seems to conflict with the present data, where a progressive increase in estimation time for as few as two items has been observed during an attentional blink. In contrast, these results fit very well with an attentional explanation of subitizing, which predicts that the deployment of multifocal attention should be impaired during the attentional blink, as attention would still be engaged in the letter identification task when the enumeration task comes up. But even if this evidence calls into question the pre-attentive status of Pylyshyn’s )I0ST’s, it does not yet establish the truth of the attention-based perceptualist’s causal hypothesis. There could still be other, independent reasons for positing pre-attentive object representations, even if these turn out not to be )I0ST’s. After all, even if a multifocal attentional model turns out to be correct, we still need to explain how attention may be simultaneously directed to objects, as opposed to regions of the visual field. There must be, at bottom, some

Joseph Levine 

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pre-attentive processes that determine the units of multifocal attention, by organizing the initial visual input into discrete perceptual elements to which attention may be allocated. There is robust empirical evidence, for example, that the visual system amodally completes objects behind occluders during very early stages of visual processing, before the allocation of attention Rensink & Enns , Driver et al. . Take the visual displays depicted in figure below. If your task is to search for a notched pac man figure, you will immediately be able to spot it in the bottom display, even as the number of distractors is increased. In the top display, however, search is slower, requiring you to serially attend to each circle in the display until the target is found. Moreover, search time also rises progressively with the number of distractor items added to the display, which is a trademark of serial processing.

)ig.

: Experimental design for pre-attentive amodal completion from Driver et al.

This provides strong evidence that the visual field over which attention roams already contains amodally completed objects, which explains subjects’ difficulties in finding the pac man figure in the top display. But if pre-attentive processes deliver a representation of the visual field where objects have already been amodally completed, then conscious attention cannot be the cause of

 0on-attentional Perceptualist Theories of Demonstrative Thought

object selection, falsifying the attention-based perceptualist’s causal hypothesis. But notice that these studies do not provide evidence for an indexing mechanism à la Pylyshyn but reveal processes of object segregation, which are responsible for organizing the initial visual input into perceptual units. Object segregation, as Vecera puts it, refers to the visual processes responsible for determining which visual features combine to form a single shape and which features combine to form other shapes” Vecera : . These processes are responsible for amodally completing the full circle behind the square in figure a above. Indeed, Pylyshyn admits that the assignment of visual indices presupposes that the visual scene has already been organized into perceptual units, which may then be picked out by )I0ST’s. As he writes, In assigning indexes, some cluster of visual features must first be segregated from the background or picked out as a unit … . Until some part of the visual field is segregated in this way, no visual operation can be applied to it since it does not exist as something distinct from the entire field. Pylyshyn :

This suggests that Pylyshyn’s )I0ST cannot be the perceptual DMM we are looking for. If we want to find, as Levine suggests, a perceptual mechanism that picks out objects in the world directly, i.e., without presupposing further object representations, we must look to an earlier level of perceptual processing, where object-centred segmentation processes parse the scene into discrete perceptual elements. It is at this level that we shall find the initial link between mind and world, the lowest level of perceptual processing where objects are picked out in the world and perceptually represented. This is exactly Raftopoulos’ suggestion, who argues that the natural analogs of demonstratives should be cashed out in terms of object-centred segmentation processes in the early vision system, which retrieve information from a visual scene and parse it into units in a purely bottom-up manner Raftopoulos & Müller , Raftopoulos a,b .

. Athanassios Raftopoulos ..

Perception, attention and cognition

We have seen, with Levine, two arguments against attention-based perceptualist theories. The first, stemming from Levine’s commitment to a computationalrepresentational theory of mind, argued that attention cannot be the cause of

Athanassios Raftopoulos 

object selection, since it is a mental operation defined over perceptual representations of objects. This argument was quickly dismissed as begging the question against the attention-based perceptualist, who puts forward an empirical hypothesis concerning the role of attention in object selection. This led us to Levine’s second argument, which appealed to empirical evidence in order to argue for pre-attentive mechanisms of object individuation and tracking, based on Pylyshyn’s work on visual indices. This evidence, however, was deemed inconclusive, and did not clearly point to pre-attentive perceptual mechanisms. All the data Pylyshyn gathered in support of visual indices – namely, multiple object tracking and subitizing – could also be explained in a multifocal attentional model or an attentional set model, for which we have independent evidence. But now Raftopoulos gives us another argument against attention-based theories of demonstrative thought. One of the main tenets of perceptualism is the claim that singular representation is to be explained at the more primitive level of perception, through processes of visual selection that pick out objects in the world directly, independently of the application of concepts in thought. The success of this theoretical project depends on showing that perception retrieves and represents objects in a visual scene in a purely bottom-up manner, encapsulated from the effects of higher cognition. On this basis, Raftopoulos argues that a non-negotiable theoretical constraint of perceptualism is that the perceptual mechanisms in question must be cognitively impenetrable. But according to Raftopoulos attention does not meet this constraint. Attention, write Raftopoulos and Müller, brings with it the involvement of memory circuits and higher cognitive centers, and thus infuses perception with conceptual content Raftopoulos & Müller : . Based on fMRI studies and electrophysiological recordings conducted by Victor Lamme and collaborators Lamme , Lamme & Roelfsema , Raftopoulos argues that the effects of attention are only registered at about ms after stimulus onset, at a level of perceptual processing where there is already significant interaction with higher cognitive centres in the brain. This provides evidence that attentional processing is cognitively penetrable, and thus cannot serve as the analogs of demonstratives at the more primitive level of perception. Rather than being the cause of object selection, attention in this picture functions to enhance processing for attended objects and integrate them into cognition, something that presupposes that objects have already been selected and perceptually represented in a preattentive manner.  See Raftopoulos : for an explicit endorsement of this claim. The term ‘cognitive impenetrability’ comes from Pylyshyn .

 0on-attentional Perceptualist Theories of Demonstrative Thought

Raftopoulos then claims that there is a level of perceptual processing, roughly corresponding to what Pylyshyn calls the ‘early vision system’, that is not affected by top-down signals from higher cognitive centres in the brain. Raftopoulos’ proposal is to define ‘perception’ properly speaking, as an autonomous level from cognition, in terms of cognitively impenetrable perceptual processing that occurs in early vision, and to identify perceptual representational content with neural states in the early vision system Raftopoulos a: . In this picture, questions about the structure of perceptual content, or what is represented in the content of perception, become purely empirical questions, to be answered by cognitive science. Only empirical investigation will tell us what neural states in the early vision system are sensitive to and what they encode, before the modulatory effects of attention and top-down signals from higher cognitive centres in the brain reach perceptual processing. So if one wants to argue, in accordance with perceptualism, that singular representation of objects is to be explained at the more primitive level of perception, one needs to show that neural assemblies in the early vision system already represent particular objects, which is exactly Raftopoulos’ proposal. Drawing support from Victor Lamme and Ronald Rensink , Raftopoulos argues that neural assemblies in early vision encode a structural representation of the scene where particular objects – or proto-objects – have already been segregated from the visual scene and represented as discrete perceptual units. This licenses us to include objects in the contents of perception, and to look for the natural analogs of demonstratives in the processes responsible for segregating objects in the scene and representing them in this manner. Therefore, the evidence suggests that perceptual DMM’s are not indexing mechanisms but pre-attentive processes of object segregation Raftopoulos & Müller : . In conformance with perceptualism, this would allow us to account for both the singular and the demonstrative questions of demonstrative thoughts at the more primitive level of perception. The reader might remember that in Levine’s model there were two levels of perception below the more sophisticated level of thought: a pre-attentive level where )I0ST’s were assigned to objects in the world on a purely causal basis, and an intermediate level of attentional perception where a subset of these )I0ST’s were selected for further perceptual processing. At the top level we had demonstrative thought – or cognitive attention – as a further selection opera-

 The nature of these ‘proto-objects’ will be examined in more detail in section . . .

Athanassios Raftopoulos 

tion on attended objects that allowed one to have conceptually structured thoughts about the objects of visual perception. In Raftopoulos’ model, in contrast, the level of perception is now restricted to the early vision system, where objects are picked out in the world through object-centred segmentation processes, which put us in a position to consciously experience and think about them. As attention already implicates cognitive penetrability and the involvement of concepts, the distinction between perceptual and cognitive attention introduced in chapter can no longer be maintained. All forms of attention are cognitive in nature, in the sense that they infuse perceptual experience with conceptual content. The difference between the two models can be captured in the following schema:

)ig.

: Contrast between Levine’s and Raftopoulos’ non-attentional perceptualist theories

Removing the intermediate level of attentional perception should not lead us to blur the distinction between object perception and demonstrative thought. In accordance with the empirically oriented nature of Raftopoulos’ project, object perception and demonstrative cognition are defined by the kind of processing that takes place at each level. Perception corresponds to perceptual processing that is encapsulated from higher cognitive centres and restricted to the early vision system. As soon as perceptual processing is modulated by attention experience becomes infused with conceptual content, and it would make no sense to distinguish, at the level of conscious attentional experience, ‘object perception’ from ‘demonstrative thought’. As we shall see in more detail in the next section, during early vision processing we are only phenomenally conscious of visual stimuli; there is conscious experience of visual stimuli at this level, although this experience is

  0on-attentional Perceptualist Theories of Demonstrative Thought short-lived and not easily reportable. In order to have access, or report consciousness, attentional processing is required. Therefore, another way to understand the distinction between object perception and demonstrative thought is through the distinction between phenomenal and access consciousness. At the level of perception, we are only phenomenally aware of objects or protoobjects ; our experience has an iconic, image-like structure, and is not easily reportable. Demonstrative thought, in contrast, arises at the level of attentional processing, where we have access consciousness of a more limited number of items in the scene. This is where perception merges with cognition, and object representations become incorporated into higher cognitive processes. To attend to x, therefore, is already a way of thinking about it, as attention brings with it the involvement of concepts, semantic memory, background knowledge, goals and expectations, etc. The perceptual states underlying demonstrative thought are not attentional states but pre-attentive states. Before we examine the empirical evidence in favour of this theory, it is important to notice that Raftopoulos presupposes a model of attention that is quite different from the other ones we’ve seen so far. In the attention-based theory presented in chapter three section . . , for example, attention was conceived as a binding mechanism: pre-attentive processing would deliver non-integrated structures which are bound to a single perceptual unit on the basis of attention. In Levine’s model, on the other hand, objects are represented pre-attentively in a small number corresponding to the number of available )I0ST’s around four . Attention is then conceived as a mental operation that intervenes in perception in order to select a subset of these pre-attentive representations for further processing. Raftopoulos, in contrast, bases his theory on a competition model of attention. In this model, attention is not the cause of selection but the result of a competition between neuronal assemblies representing multiple stimuli i.e., proto-objects in order to see which ones will enter visual working memory. After proto-objects have been segregated from the background, bottom-up salience cues or abrupt onsets and top-down factors the goals and expectations of the observer bias the competition towards one or a few stimuli that happen to be more behaviourally relevant for the task at hand. The stimuli that win the competition get to enter visual working memory, but as Raftopoulos puts it, "it is the object or objects that win the competition that are said to be attended rather  Raftopoulos b: - ; Lamme ‘access’ consciousness see Block . Desimone & Duncan , Vecera

:

. )or the distinction between ‘phenomenal’ and

, Reynolds & Desimone

.

Athanassios Raftopoulos 

than the case being that some faculty, namely attention, determines or selects the winner” Raftopoulos b: . The crucial difference is that in competition models attention is a dynamic property of the system, arising from competitive interactions between bottom-up and top-down processing, rather than a further mental operation that intervenes in perception in order to select a subset of represented stimuli for further processing. This model of attention should be kept in mind when we discuss Raftopoulos’ theory.

.. Three levels of visual processing Raftopoulos’ theory is heavily based on Victor Lamme’s model of perceptual processing Lamme , Lamme & Roelfsema , so it might be worth going over this model in some detail. Based on fMRI studies and electrophysiological recordings, Lamme proposes a distinction between three stages of visual processing: the feedforward sweep ))S , local recurrent processing LRP , and global recurrent processing GRP . These stages are defined and distinguished from one another in terms of latencies of visual responses. The ))S starts at about ms after stimulus onset when the first patterns of activation are registered in V , and lasts until - ms with the activation of most visual areas in the ventral and dorsal streams Lamme : . 0euronal activity at this stage, as its name indicates, only moves forward in the hierarchy of visual areas, never sideways or backwards. )urther on, there is very little perceptual organization at this stage; contours are extracted but not yet assigned to perceptual elements i.e., there is no figure-ground segregation . Basic features like colour and orientation are also registered in feature maps, but not yet bound together. More importantly, there is no conscious experience of visual stimuli during processing in the ))S. One of Lamme’s main goals in distinguishing these levels is precisely to argue in favour of recurrent processing as the neural correlate of visual awareness, so it follows that visual stimuli processed during the ))S are unconscious by definition. These stimuli will not be consciously perceived unless they reach the subsequent level of local recurrent processing, not even if they are attended to. Masked stimuli, high temporal and spatial frequencies, or dominated stimuli in binocular rivalry are good examples. These stimuli cause activation of cells during the ))S, but as they do not benefit from recurrent processing, they are never consciously perceived Lamme : - . The first signs of recurrent processing are registered at about - ms, as horizontal and feedback connections are established in the same areas that were activated during the initial ))S. This is the level of ‘local recurrent pro-

114 | Non-attentional Perceptualist Theories of Demonstrative Thought

cessing’ (LRP), which is local to visual areas and cognitively impenetrable. As the connections between populations of neurons encoding different features are strengthened through recurrent horizontal and feedback connections, some of these features may be bound together before the modulatory effects of attention are registered. Notice that this binding model is very different from Feature Integration Theory, where attention is posited as the “glue” that binds features together to one and the same object, through the attended location becoming activated in a master map of locations. Lamme's model, in contrast, acknowledges feature binding at multiple levels across the visual hierarchy, with or without attention, from the binding of simple features through recurrent horizontal and feedback connections, to the binding of more complex stimuli that requires focal attention (Lamme & Roelfsema 2000, Roelfsema 2005). Figure 15 below provides a good illustration of feature binding that occurs on the basis of recurrent processing without attention. The bottom panel shows a visual display with a yellow circle on the left and a red triangle on the right. Immediately above it, an early visual area EV contains neurons that are sensitive to conjunctions of colours and locations. These conjunctions, however, are formed through reciprocal horizontal and feedback connections between EV and visual area TI, which responds only to colour but not to location, and a spatial salience map SaM, which responds to the presence of stimuli at certain spatial locations. As the connections illustrated in bold lines are strengthened through recurrent processing and connections in dashed lines suppressed, binding of colour and location may be achieved during the LPR without the need of focal attention (Roelfsema 2005: 229).

Fig. 15: Model of pre-attentive feature binding (from Roelfsema 2005)

Athanassios Raftopoulos 

This provides an example of how the visual system is able to construe a complex structural representation of the scene through recurrent processing in different visual areas, binding some features together and segregating perceptual elements from the background. According to Lamme, the perceptual representation of the scene during the LPR consists in tentatively bound features and surfaces” Lamme : , roughly corresponding to David Marr's / D sketch . These features and surfaces are only tentatively bound because they may be overridden by subsequent attentional processing. Moreover, as neurons at this stage of visual processing have relatively large receptive fields, there is little competition between stimuli, and multiple perceptual elements - i.e., proto-objects – can be simultaneously represented. And as recurrent processing according to Lamme is the neural correlate of visual awareness, at this level there is already conscious experience of visual stimuli, although in a form that is iconic, short-lived, and not easily reportable. In other words, we have phenomenal awareness of Marr's / D sketch containing multiple proto-objects, but not access or report awareness, which requires global recurrent processing Lamme : . Up until this point, the horizontal and feedback connections that characterize LPR are local to visual areas, registered before the modulatory effects of attention and before information flows to and from higher cognitive centres in the brain. Therefore, the ))S and the LRP correspond to what Raftopoulos calls ‘perception’: a level of perceptual processing that is pre-attentive, cognitively impenetrable, and of which we have only phenomenal awareness. More importantly, a level where proto-objects have already been segregated from the background and perceptually represented through horizontal and feedback connections established during the LRP. This allows us to posit the set of processes responsible for segregating proto-objects from the background as the natural analogs of demonstratives at the more primitive level of perception. Or to put it in our current terminology, these processes are perceptual DMM’s: they are the lowest-level mechanisms that explain how objects or proto-objects are represented in the visual system. As these recurrent interactions grow more and more widespread, they eventually reach areas in executive and mnemonic space i.e., frontal, prefrontal, and temporal cortex . At this point there is ‘global recurrent processing’ GRP , where, as Lamme puts it, "visual information is put into the context of the systems' current needs, goals and full history” Lamme : . Here is also where the modulatory effects of attention are first registered, at about ms. This provides good evidence that attention indeed "infuses perception with conceptual content", as Raftopoulos claims. As neuronal activation moves upwards

 0on-attentional Perceptualist Theories of Demonstrative Thought

and grows more widespread, neuron's receptive fields become increasingly smaller, and competition among stimuli starts to arise. Attention comes in to bias the competition towards one or a few stimuli, according to the goals, desires and expectations of the perceiver, relocating attended elements from iconic to working memory and allowing one to report on one’s experience of attended items. Attention, in other words, is what brings the object into one’s cognitive life and integrates it into one’s cognitive system. As recurrent connections to higher cognitive centres in the brain are established and attention bias the competition towards one of these objects, one may recognize the attended object, make verbal reports about it, and think about it in various ways. But this presupposes that objects have already been perceptually represented, at a level of perceptual processing that is encapsulated from higher cognitive centres. In accordance with perceptualism, this allows us to explain our capacity for singular representation at the more primitive level of perception, through the set of objectcentred segmentation processes responsible for segregating multiple protoobjects during the ))S and LPR stages of visual processing. These processes will determine which particular object one’s thoughts and verbal reports concern. As Raftopoulos and Müller put it: We argue that causal chains relating the world with mental acts of perceptual demonstration single out the demonstrata and attach mental particulars to things. In a linguistic context our claim is that these causal chains fix the reference of the perceptual demonstratives in a nonconceptual and nondescriptive way. The causal relation is provided by the nonconceptual contents of perceptual states that are retrieved in bottom-up ways from a visual scene by means of preattentional object-centered segmentation processes. Raftopoulos & Müller :

But here one may object. Granted, there is strong empirical evidence for preattentive representations of proto-objects in the early vision system, which are the output of object-centred segmentation processes. But what exactly is the nature of these representations? As seen in chapter one section . , there are two basic constraints governing object representation: individuation and maintenance of numerical identity. Can proto-objects meet these two constraints? As the output of segmentation and segregation processes, they plausibly meet the first constraint: after all, the function of these processes is precisely to individuate perceptual elements in a visual scene. As Vecera puts it, object segregation refers to the visual processes responsible for determining which visual features combine to form a single shape and which features combine to form other shapes” Vecera : . But without the benefits of attentional processing,

Athanassios Raftopoulos 



do these representations maintain their numerical identity in time? In the next section I will present some empirical evidence that suggests a negative answer to this question.

..

Proto-objects and the coherence problem

When Raftopoulos introduces proto-objects he appeals to the work of Ronald Rensink, where proto-objects are functionally defined in the following way: . They are the highest level outputs of low-level vision; . They are the lowest-level operands upon which attentional processes can act Rensink : . In Rensink’s model, the function of low-level vision is to provide a quick and dirty interpretation of the visual scene, yielding a rough structural sketch that provides the basic ‘gist’ of the scene. In this structural representation multiple perceptual elements i.e., proto-objects are simultaneously represented, although they are still volatile and short-lived at this point Rensink : . The function of attention in Rensink’s theory is to endow these short-lived representations with greater coherence in space and time hence the theory’s name: ‘the coherence theory of attention’ . Attention acts as a hand that grabs a small number of proto-objects – around four – and forms a so-called ‘coherence field’, a stable representational structure that persists for as long as attention is maintained on these items, allowing them to enter visual short term memory. After attention is disengaged, the coherence field dissolves into its constituent and unstable proto-objects Rensink : . So far this is compatible with Lamme’s model reviewed in section . . , where pre-attentive processing provides a structural representation analogous to Marr’s / D sketch. In a similar vein, the ‘gist’ of the scene in Rensink’s picture is something of which we are only phenomenally aware, and which is constantly regenerated as our eyes move across the scene. But as attention is required in order to see change, we are not aware of this constantly changing flux: we remain only phenomenally aware of the basic gist of the scene, a virtual representation that merely seems stable and constant to us Rensink : .  See Rensink : . One of the main goals of Rensink’s coherence theory is also to provide an account of perceptual change and inattentional blindness, or the inability to perceive change when the changing elements are not attended to.

 0on-attentional Perceptualist Theories of Demonstrative Thought

However – and here lies the main problem for Raftopoulos’ perceptualist theory – in Rensink’s model proto-objects have very limited coherence in space and time, inevitably decaying after a few hundred milliseconds or being immediately replaced whenever a new stimulus appear at the same retinal location where a proto-object had been previously represented Rensink : fn . In fact, one of Rensink’s main conclusions is that in order for the visual system to maintain an object representation in time, attention is required. Here’s Rensink: Given that unattended structures have only limited spatial and temporal coherence, it follows that focused attention must provide the coherence that knits them into larger-scale objects and allows them to retain their continuity over time. Rensink :

These considerations strongly suggest that the proto-object representations Raftopoulos appeals to cannot meet the second constraint on object representation. Although they might be able to meet the individuation constraint, as discrete perceptual elements upon which attentional processes may act, these representations do not persist for more than an eye saccade, thus failing the ‘maintenance of numerical identity’ constraint. So if attention is needed to endow these volatile and unstable proto-object representations with spatiotemporal coherence, it could still be true that attention is the cause of object selection. After all, attentional processing would be the lowest-level perceptual mechanisms that explain how objects and not just proto-objects are represented in the visual system. As Rensink suggests, attention may do this by selecting a few items from the unstable flux of proto-objects and creating a ‘coherence field’ around them, which would persist for as long as attention is sustained. This is what allows one to perceive an object as the same through time and motion. Or, to put it in the vocabulary of competition models of attention, the objects in the coherence field would be those that won the competition between bottom-up and top-down processing, in virtue of being more behaviourally relevant in the context of the agent’s goals. But now the perceptualist might have a problem in her hands. If attention is required for object representation to be possible, and if attention, as the evidence presented by Raftopoulos suggests, implicates higher cognitive processing, does this mean that a perceptualist account of singular object representation is unfeasible? 0o, it does not. This would be the case only if we needed to appeal to conceptual knowledge in order to account for the greater spatiotemporal coherence that is characteristic of genuine object representations, but nothing in what was said so far suggests this interpretation. In Rensink’s coherence theory, for ex-

Athanassios Raftopoulos 

ample, attention endows object representations with spatiotemporal coherence in virtue of these representations entering visual short-term memory Rensink : . 0othing in this explanation requires us to appeal to more sophisticated conceptual abilities in order to explain how these representations persist in time. Although at this level of processing there may be recurrent connections to higher cognitive centres in the brain, as long as spatiotemporal coherence is not imposed onto the objects of perception by higher conceptual abilities, perceptualism may still be a viable theoretical option. To conclude, non-attentional theorists like Levine and Raftopoulos are right to emphasize the importance of pre-attentive processing in a theory of singular representation and thought, especially if one of the goals of the theory is to connect the mind and the external world in nonconceptual terms. But at the same time, we’ve also seen that pre-attentive representations are too volatile and unstable to explain how perception picks out objects in the world and put us in a position to have demonstrative thoughts about them. These pre-attentive mechanisms seem too primitive to be a perceptual DMM according to the definition proposed in section . . . )or perception to represent objects as discrete perceptual units that retain their identity in time, attention is required. But rather than this conclusion being a problem for perceptualism, what this suggests is the possibility of a hybrid perceptualist theory, one that acknowledges an important role for both pre-attentive and attentional processing. )irst, pre-attentive processes segregate perceptual elements in the scene in a purely bottom-up manner, providing the basic units upon which visual attention operates and connecting mind and world in a nonconceptual manner. These units, however, are not yet object representations. With the allocation of attention these pre-attentive representations are endowed with greater spatiotemporal coherence, allowing one to represent an object that retains its numerical identity in time. As per perceptualism, our capacity for singular representation is explained at the more primitive level of perception, on the basis of both pre-attentive and attentional perceptual processing. Once an object has been segregated from the background and attention has been allocated to it, we are in a position to have demonstrative thoughts about it. But before we settle on this theory, I would like to examine one final nonattentional view: according to Mohan Matthen / , what explains how perception puts us in a position to have demonstrative thoughts about objects is something he calls ‘motion-guiding vision’, which roughly corresponds to the processing of visual information along the dorsal stream. As processing in the dorsal stream is associated with the representation of visual information in egocentric coordinates for the control of motor action Milner & Goodale ,



 0on-attentional Perceptualist Theories of Demonstrative Thought

this model introduces a novel and important element that has been neglected so far in our discussion of perceptualism: the connections between object perception, demonstrative thought and action. If Matthen is right, we are looking at the wrong place when we posit segmentation processes as the pre-attentive mechanisms that provide the units of visual attention. As Matthen puts it, being able to attend to something is, among other things, a physical thing. It depends on the subject’s ability to turn his eyes to the thing, fixate it, focus on it, etc. [And] vision controls attention through egocentric location coordinates” Matthen : . As motion-guiding vision is what provides egocentric location coordinates, it follows that motion-guiding vision, not segmentation processes, is the non-attentional mechanism we need.

.

Mohan Matthen

. .

Seeing objects versus seeing pictures

Let us start by noticing that there is an important difference between seeing real three-dimensional objects in space and being presented with a pictorial depiction of the same scene down to its minute details, as seen from the same vantage point. This difference cannot be traced to differences in some property of objects that is represented in experience, since these properties are stipulated to be the same in both the real scene and the picture. Rather, one important difference seems to be this: in genuine object perception the objects are felt to be perceptually present in our external environment, as real things out there we can physically manipulate and act upon. This feeling of perceptual presence, however, does not accompany our perception of objects in a picture. If something is felt as perceptually present in the space around us, it is the surface of the picture itself, and not the objects it depicts. )or where would these objects be? 0ot in the surface of the picture, which only contains the pixels that represent the objects in question. 0or, say, five meters away into the wall where the picture is hung, which is where they would be if the picture was actually a window onto another room. )or if this were the case, if we moved closer to the picture the objects should also appear to be closer to us, but phenomenologically speaking, this is not the case. The picture is closer to us, but not the objects it depicts, which remain at some unspecified distance. In a similar vein, our perspective upon these objects does not change as we move to the right or to the left; all the visual angles and occlusion rela-

Mohan Matthen 



tions between objects depicted in the image remain unchanged. The space in the picture, as Matthen puts it, lacks a ‘here’ Matthen : . Moreover, apart from this lack of spatial connection there is no temporal connection to objects in a picture either. )or suppose the picture depicts a coffee cup falling from the edge of a table. When is the cup falling from the table? If we were talking about perception, the answer would be clear: now, a time indexed to the time of the perception, which allows us to try to reach for the cup in order to prevent it from shattering on the floor. But in the case of the picture, we would have to say: at the time the picture was taken. But we have no information about what time that is. There is no connection between the time of the events depicted in the picture and the time of the perception. Time in the picture also lacks a ‘now’ Matthen : . In short, there is in genuine object perception a kind of spatiotemporal relation to objects that is absent in a perception of a picture of objects, even if the picture depicts them in the same way, i.e. as having the same surface features and as seen from the same vantage point. In genuine object perception the perceived objects are here, in the space around us, and now, at the time of the perception. They are felt as perceptually present. In a pictorial depiction, in contrast, objects are not felt as things we can physically manipulate and act upon. This is so even if both cases rely on pre-attentive processes of object segregation. After all, in order to perceive objects in a picture our visual system also needs to segregate the surfaces that belong to the coffee cup and those that belong to the table from the background or, to be more precise, the pixels that represent those surfaces , so that we can perceive a picture depicting a coffee cup falling from the edge of a table. But these segregated surfaces are not objects in the here and now; what our visual system has segregated are only pixels printed on the surface of photographic paper. This suggests that object segregation processes are insufficient to explain how perception picks out objects in the world and put us in a position to cognitively engage with them in various ways. This, Matthen argues, is the job of ‘motion-guiding vision’ – the part of the visual system dedicated to processing spatial information to guide the body in motor action and physical manipulation, which functions like deictic pointers to objects in one’s external environment. When one approaches an object, motion-guiding vision will automatically assign a spatial position for that object in agent-centred coordinates, thus allowing one to shift attention to this object and physically manipulate it in

 See also 0anay

:

.

  0on-attentional Perceptualist Theories of Demonstrative Thought various ways. This suggests that assignment of egocentric location by motionguiding vision is a more plausible candidate for the natural analog of demonstratives at the more primitive level of perception.

. . Motion-guiding vision and visual reference There is strong evidence in cognitive science that the mechanisms that control processes like direction of gaze to a sudden change in the visual periphery, or grip alignment when reaching to pick up an object, are largely independent from perceptual mechanisms that make one consciously aware of visual features such as colour, shape, motion, etc. Matthen calls this latter set of processes ‘descriptive vision’, whose function is to provide the perceiver with information about properties like shape, colour, etc., in a format that is suitable for epistemic purposes. In other words, descriptive vision provides the perceiver with conscious, relatively stable visual information in object-centred or scene-centred coordinates, which one can hold in memory for a period of time so that one can assess its behavioural relevance in light of other incoming information, background knowledge and past experience. Motion-guiding vision, in contrast, provides information about the spatial locations of objects in agent-centred coordinates, suitable for the online control of motor action. Differently from spatial information processed by descriptive vision, which is relatively stable and centred on objects in the scene, spatial information computed by motion-guiding vision is constantly changing as perceiver and/or object move, and has no lasting significance Matthen : . To illustrate with an example, imagine keeping your attention focused on two coffee cups sitting on top of a table as you slowly circle around it; once you o have completed an circle around it, the spatial orientation of the two cups will have reversed from left to right. And yet, as long as you keep your attention focused on the cups throughout this period of observation, there is no confusion about which cup is which. This is because of descriptive vision, which computes spatial relations in object-centred or scene-centred coordinates that are preserved as the observer and/or the object move in relation to one another. In contrast, the spatial information that allows you to reach for the right location in order to grab one of the cups, or choose the correct grip when picking it up by

 See Milner & Goodale

for review.

Mohan Matthen 



its handle, must be constantly updated as you move in relation to the cups. Every time your eyes, hand, or body change position relative to the cups, the parameters that guide your motor actions must be updated accordingly. )or the guidance of motor action, having more stable spatial information in object or scene-centred coordinates would do no good. Computing these parameters in agent-centred coordinates, suitable for the online guidance of motor action, is the job of motion-guiding vision. Moreover, there is accumulating evidence that these two functions of the visual system are, to a large extent, anatomically independent. Processing visual information for the online control of motor action in agent-centred coordinates has been associated with processing along the dorsal visual pathway, which runs upwards from the primary visual cortex to the parietal lobe at the top of the head. In contrast, processing visual features in object-centred coordinates for epistemic purposes like identification and recognition has been associated to processing along the ventral visual pathway, running from the primary visual cortex to a part of the brain located just behind the ears, in the lower temporal lobe. The distinction between a dorsal and a ventral visual stream was initially proposed by Ungerleider & Haxby as a distinction between a ‘where’ dorsal system that locates objects in space, and a ‘what’ ventral system that provides descriptive information about objects for the purposes of identification and recognition. 0owadays, however, it is widely acknowledged that spatial information can also be processed in the ventral stream, and that, conversely, some featural information is processed in the dorsal stream as well. The current distinction is that between a visual system that directly guides motor interactions with one’s external environment bypassing higher cognitive centres in the brain, and a system that represents and stores features of objects in working and long term memory for epistemic purposes. Milner & Goodale have famously called these two systems ‘vision for action’ and ‘vision for perception’ respectively, but for the purposes of the present discussion I will stick to Matthen’s terms ‘motion-guiding vision’ and ‘descriptive vision’, which are supposed to be functionally equivalent. The most compelling evidence in favour of this anatomical distinction comes from brain lesions that cause damage to one of these visual pathways while leaving the other intact. Patients with lesions in the dorsal visual stream, for example, are able to recognize objects and even describe their relative loca-

 Milner & Goodale

, Jacob & Jeannerod

.

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 0on-attentional Perceptualist Theories of Demonstrative Thought

tions, but they have severe difficulties in directing their hands or configuring their fingers properly when attempting to reach for these objects. In contrast, when the lesion is local to the ventral visual stream, patients are unable to recognize everyday objects or faces of friends and relatives, but show striking accuracy in coordinating hand and finger movement when reaching for the very same objects they fail to recognize. The first condition is called optic ataxia, while the second one is called visual form agnosia. Both are well documented in the relevant literature, and provide evidence of visual specialization and the anatomical separation of both pathways. Moreover, evidence for this distinction can also be gathered from studies with normal subjects in the context of perceptual illusions. Take, for example, the Ebbinghaus illusion depicted in figure below, where a target disk surrounded by smaller disks appears to be larger than a disk of equal size surrounded by larger disks. Although the two disks perceptually appear to differ in size, Aglioti et al. have found that when subjects attempt to reach for the central disks in order to pick them up in a three-dimensional version of the illusion with poker chips , the visual system that controls the scaling of grip aperture is not fooled by the illusion: subjects choose exactly the same grip aperture regardless of which of the two poker chips they attempt to pick up.

)ig.

: The Ebbinghaus illusion

 Goodale & Milner , Goodale et al. , Milner & Goodale . The same experiments have also been conducted by Haffenden & Goodale , with similar results. In addition, Daprati & Gentilucci have also tested subjects’ motor actions directed at arrows that appear to differ in size, as in the Müller-Lyer illusion. They have also found that the ‘vision for action’ system, or motion-guiding vision, is not fooled by the illusion.

Mohan Matthen 



This provides good evidence for a difference in the metrics and frames of reference used by both visual subsystems. As descriptive vision computes featural and spatial information about objects relative to other objects in the scene, we should expect it to be vulnerable to illusions of this kind due to size-contrast computations: an object that is smaller than its immediate neighbours is assumed by the descriptive visual system to be smaller than a similar object that is larger than its immediate neighbours. This gives rise to a conscious perceptual experience of the left-hand circle as larger than the right-hand one. Motionguiding vision, in contrast, uses metrical computations that are insensitive to the kind of contextual cues that give rise to the illusion, delivering information about the true size of the target that may be used for correct grip calibration. As a consequence, it is not fooled by the perceptual illusion. But although the evidence points to an anatomical separation between the dorsal and the ventral visual pathways, it is important to notice that Matthen’s distinction between descriptive and motion-guiding vision is a functional one. It points to a distinction between two different functions of the visual system: to compute visual information about objects in agent-centred coordinates for the online control of motor action motion-guiding vision , and to compute visual information about objects in object-centred coordinates for epistemic purposes like identification and recognition descriptive vision . This is so regardless of which specific brain structures subserve each of these functions. As Matthen puts it, motion-guiding vision is a term that takes the functional implications of the [dorsal and ventral distinction] without making a specific commitment to what areas of the brain are involved” Matthen : . So even if there is some controversy as to the extent to which these two visual pathways are anatomically independent, this debate need not concern Matthen’s distinction, as long as its functional implications can be maintained. And the evidence presented in this section strongly speaks in its favour. With this distinction in hands, Matthen’s thesis is that motion-guiding vision is the perceptual mechanism responsible for picking out objects in the world and putting us in a position to cognitively engage with them. It does so by furnishing the perceiver with a location for the object in agent-centred coordinates, which guides motor actions in relation to it including the motor action ‘shift attention to [x]’, where the value of [x] is an egocentric location which  But see )ranz et al. for contrary evidence, and Goodale & Wolf for general discussion. See Jeannerod for evidence of significant interactions between the two visual pathways.

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 0on-attentional Perceptualist Theories of Demonstrative Thought

motion-guiding vision has assigned to the object . This egocentric location uniquely determines which object one perceives and thinks about. Let’s go back to the contrast between seeing real objects and seeing objects in a picture. In the latter case, motion-guiding vision does not assign egocentric location to the depicted objects, independently of the egocentric location of the picture itself. Only objects in real space , says Matthen, can be assigned egocentric coordinates : . In the picture case, the spatial coordinates of the depicted objects that allow one to shift attention to them are in fact coordinates of parts of another object: the picture itself. When you shift attention to the various objects depicted in the picture, you are in fact shifting attention to different parts of the same object, namely the picture. This is because the picture is the only real object in space which is assigned an egocentric location by motionguiding vision. The objects depicted in the picture, in contrast, are represented only through descriptive vision. As Bence 0anay puts it, When we see an object face to face, our dorsal and ventral visual subsystems attribute properties to the same object: the perceived object. When we see objects in pictures, in contrast, the dorsal and the ventral visual subsystems attribute properties to different objects. The ventral subsystem attributes properties to the depicted scene whereas the dorsal subsystem attributes properties to the surface of the picture. 0anay :

This explains why depicted objects in the surface of a picture are not felt as perceptually present. The feeling of perceptual presence, as Matthen puts it, is a phenomenological consequence of motion-guiding vision assigning egocentric locations to objects in the space around the subject : . In picture perception, the only real object which one can demonstratively refer to and think about is the picture itself. To repeat a point made earlier, as segmentation processes are also involved in our perception of depicted objects, they cannot explain how visual perception picks out objects in the world and put us in a position to cognitively engage with them. This is the job of motion-guiding vision, which assigns egocentric locations to objects in our external environment. This assignment of egocentric location functions as a sort of demonstrative reference to external objects, a purely deictic relation explicated at the more primitive level of perception Matthen : .

 Although 0anay here talks of the ventral and dorsal visual streams, he also endorses a functional interpretation of this distinction, and explicitly compares his account with Matthen’s : . Therefore, we may safely take 0anay’s usage of ‘ventral’ and ‘dorsal’ as equivalent to Matthen’s descriptive and motion-guiding vision respectively.

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0ancy Kanwisher has presented empirical evidence in support of Matthen’s claim that motion-guiding vision is the source of the ‘feeling of perceptual presence’ of objects. Kanwisher distinguishes two forms of visual awareness of objects: content-dependent and content-independent. The first corresponds to awareness of properties of objects like their colours or shapes, and is traced to recurrent processing along the ventral stream. However, as Kanwisher points out, there is also a content-independent element of visual awareness, which Kanwisher describes as a what it’s like to be aware of external things, a feeling of perceptual presence that cannot be traced to an awareness of properties these objects might possess. Kanwisher’s claim is that this form of awareness is correlated with enhanced activity along the dorsal stream, something that fits very well with Matthen’s hypothesis that motionguiding vision, functionally associated with processing in the dorsal stream, is responsible for the feeling of perceptual presence of objects Kanwisher : . It should be noted, however, that although motion-guiding vision controls attentional shifts, it does not do so by pre-attentively representing objects in space, to which attention could then be allocated. In this sense, Matthen’s nonattentional theory is very different from Levine’s or Raftopoulos’, where preattentive representations of objects or proto-objects were posited as the basic units of visual attention. Matthen is careful to point out that what motionguiding vision provides are the egocentric locations of points in the object’s surfaces, which are constantly updated as object and/or perceiver move, and which guides one’s actions in relation to that object including attentional shifts . As he puts it, motion-guiding vision gives you, directly, reference to certain objects, or rather to points on their surfaces : , my emphasis . Therefore, motion-guiding vision does not strictly speaking represent objects. In order to perceptually represent an object as a discrete perceptual element that retains its numerical identity in time, the visual system needs among other things to segregate the surfaces that belong to the object from surfaces that belong to other objects. But in order to assign egocentric location to parts of objects for the control of motor action, no process of figure-ground segregation or gestalt grouping is needed; reference is only to points in space where objects are located : . At first, this claim might seem surprising. How could we, for example, know how to pick up a coffee cup by its handle without first segregating the shape of the coffee cup from the background, or without having information about the overall size of the cup? This seems strange. There is, however, empirical evidence that the spatial coordinates that control grip aperture and the movement

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of our fingers as we reach for objects are not controlled by a representation of the overall shape or size of the thing we act upon. On the contrary, the evidence suggests that the movement of each digit is programmed and controlled in an independent fashion Smeets & Brenner / . As we reach for a coffee cup, the index finger is directed to a point at one end of the cup’s handle an egocentric location supplied by motion-guiding vision , and the thumb to a point at the other end. 0o information about shape or size is needed for the motor system to execute this task. Only the egocentric locations of these two points in space are required, corresponding to both edges of the object to be acted upon. This evidence supports the claim that motion-guiding vision does not perceptually represent objects. Rather, it provides egocentric coordinates for points falling on the surfaces of objects, which the visual system can use in order to guide and control motor actions in relation to them. As Matthen puts it, there is in motion-guiding vision a wholly or largely non-descriptive reference to parts of material objects, a deictic element akin to ostension in language” Matthen : , my emphasis . As such, Matthen’s theory cannot by itself be the perceptualist theory we are looking for, as it is not the purpose of motion-guiding vision to perceptually represent objects. Differently from Levine or Raftopoulos, who argued against attention-based theories on the grounds that objects were perceptually represented before the allocation of attention, Matthen grants that attention might be required in order for object representation to be possible : . Motionguiding vision, in this picture, comes in as the perceptual mechanism which guides the allocation of attention to objects, by assigning egocentric location to points on their surfaces. It is a primitive deictic relation that makes the allocation of attention possible. This gives us a hybrid perceptualist theory that is quite different from the one sketched at the end of section . . . In that theory, pre-attentive processes of object segregation segmented the initial visual input into discrete perceptual elements i.e., proto-objects , thus providing the basic units upon which visual attention operates. These units, however, were not yet object representations. With the allocation of attention these pre-attentive representations were endowed with greater spatiotemporal coherence, allowing one to perceive an object that retained its numerical identity in time, and putting one in a position to have demonstrative thoughts about it. But if Matthen’s theory is right, what we should now say is that motionguiding vision guides and controls the allocation of visual attention, by assigning egocentric locations to points on the surfaces of material objects. When

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attention is allocated to one of these points, it will uniformly spread to the entire surface of the object a signature mark of object-based attention as argued in section . . . This allows one to perceive the object as a unitary entity that retains its identity in time. Although segmentation processes are undoubtedly involved in this story, they need not be explicitly mentioned in an account of how vision manages to pick out objects in the world and put us in a position to have demonstrative thoughts about them. There is, however, one basic problem with Matthen’s account. As Matthen is ready to admit, motion-guiding vision is only able to assign egocentric locations to objects in near space, i.e., the space immediately surrounding one’s own body, no further than an arm’s reach Matthen : - . But this is puzzling: motion-guiding vision is supposed to be the perceptual mechanism responsible for picking out objects in the world and controlling the allocation of attention, and yet, we seem normally able to single out, attend to, and think demonstratively about objects beyond near space. In fact, our paradigmatic example of a demonstrative thought in this book involves precisely an attentional relation to and a demonstrative thought about a distant object, located far beyond the subject’s near space: this is the case where one gazes out of the window onto an urban landscape and visually selects a particular building among others. How is this possible, given that motion-guiding vision cannot assign the building a location in agent-centred coordinates? In the next section I will present and criticize Matthen’s answer to this question, and propose an alternative solution.

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Referring to objects without motion-guiding vision

Matthen says that when motion-guiding vision is not available, demonstrative reference and thought about distant objects is achieved via descriptive vision, which represents the spatial locations and relations of distant objects in scenecentred coordinates, much like the way they are represented in a picture. When we look at a pictorial depiction of objects, for example, we grasp their spatial locations relative to one another, but there is no information about the distance between these objects and us. This also seems to be a phenomenologically adequate description of our perception of distant objects. To go back to the building example, if we take a few steps back from the window while keeping the building in sight, phenomenologically speaking our overall distance to the

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- , 0anay

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building remains unchanged: it doesn’t seem to be any further or closer from us contrary to the window frame, for example . This is precisely what we should expect if the spatial locations of distant objects were represented only by descriptive vision in object-centred coordinates. But this is unhelpful. Perception of objects in pictures contrasts with perception of real objects in that only the latter supports demonstrative reference and thought, a contrast that is cashed out in terms of motion-guiding vision assigning egocentric locations to objects in real space. In addition, only objects in real space are felt as perceptually present, something that was also explained through processing by motion-guiding vision. In short, only motion-guiding vision provide us with the spatiotemporal connection that is characteristic of genuine object perception, and which puts us in a position to cognitively engage with objects in various ways. When objects are represented through descriptive vision alone – for example, when we look at objects in a picture – they are not felt as perceptually present. Here’s Matthen: In the normal case of looking at a picture, there is a disconnection. Your space stops just where the space of depicted objects begins. The picture is there, right in front of you, but the [objects] it depicts are not. Agent-centred spatial coordinates are needed to make the connection between the two spaces, and seeing in pictures, which depends on descriptive vision, cannot provide them. The space in the picture lacks, if you will, a here. Matthen :

But although I have already granted that this is an adequate characterization of picture perception, this is not how we perceive real three-dimensional objects beyond near space. When I attend to a building in the urban landscape below, it does not feel like I’m looking at a picture of the city as seen from my office window. It certainly feels like there is a real building out there, below me, in the hic and nunc, a three-dimensional material object I can attend to and think demonstratively of. If I take a picture of the urban landscape as seen from the same vantage point, develop it in the same size as the window frame and hang it next to it, there would be a clear phenomenological difference between looking through the window and looking at the picture. When I gaze out of the window, it does feel as if the objects I see are spatiotemporally connected to me, as if they are out there in the world, in my hic & nunc. But if agent-centred spatial coordinates are needed to make the connection between the two spaces , as Matthen claims, how is it that the space where the building is located is connected to the space where I am located, given that the building is not assigned a location in agent-centered coordinates? How is it that I can single it out, attend to it, and think demonstratively about it in the absence of processing by motionguiding vision?

Mohan Matthen 

Matthen’s reply is that visual perception presents us with distant objects as perceptually present due to descriptive vision representing them as spatially related to other objects in the scene. These objects are, in turn, represented by descriptive vision as spatially related to other objects that are closer to us, and so on successively eventually leading back to objects in our near space which have been assigned egocentric locations by motion-guiding vision : - . In other words, distant objects will have egocentric locations derivatively, in virtue of being related to objects in near space which have been assigned egocentric locations directly. This explains why distant objects are felt to be perceptually present and why we are able to single them out, attend to them and think demonstratively about them. This is not so in the case of objects in a picture, which are not related to other objects in real space beyond the surface of the picture. Objects in pictures do not have egocentric locations, not even derivatively. Consequently, we cannot think demonstratively about them. But this cannot be right. Even if there is nothing at all between me and the buildings, it still feels like these buildings are perceptually present, like they are real objects out there in the hic and nunc, things I can attend to and think about. There is a striking phenomenological difference between seeing a building below us at a distance and seeing a picture of a building, a difference that is traced to the feeling of spatiotemporal connection we have with the real building as opposed to its pictorial depiction. But how can we explain this spatiotemporal connection when the building is not spatially related to other objects in near space? If motion-guiding vision does not assign this building an egocentric location, be it directly or indirectly, it cannot be true that this feeling of spatiotemporal connection is a phenomenological consequence of assignment of egocentric location by motion-guiding vision, as Matthen claims. In order to avoid these difficulties, my suggestion is to explain this element of spatiotemporal connection in terms of a practical, sensorimotor knowledge of what objects are and how they behave, acquired through repeated patterns of interactions with objects in the world, and manifested in our perceptual expectations and anticipations in relation to objects’ behaviours in space. One way to cash out this knowledge is through the sensorimotor theory of visual perception O’Regan & 0oë , 0oë & O’Regan . According to this theory, to perceive an object is matter of being attuned to the structure of sensorimotor contingencies governing the visual exploration of one’s environment, i.e., the set of implicit rules of interdependence between visual stimulation and movement. These rules are partly determined by the fact that objects are threedimensional, solid entities embedded in a three-dimensional environment – for example, that the size of the retinal projection depends on distance, that the

  0on-attentional Perceptualist Theories of Demonstrative Thought retinal image only provides a view of the front of the object, that when we move around it parts of the object appear and disappear from view, that the colour and brightness of the object change as it moves in relation to the light source, and so on. These rules would be very different in a space with a different structure. Through repeated patterns of interactions with objects in space, we gradually learn to be sensitive to the set of sensorimotor contingencies which govern the behaviour of three-dimensional objects in space, thus acquiring a practical, sensorimotor knowledge of objects O’Regan & 0oë : . In this picture, the element of spatiotemporal connection is built into the very notion of what it is to perceive an object, as a form of practical, sensorimotor knowledge of the object’s embeddedness in a three-dimensional space, a space which the subject herself occupies and moves about. To perceive an object, in other words, is a way of actively engaging with the object in space, to be sensitive to the way properties of the object change as a result of eye/body movements, attentional shifts, etc. To go back to the building example, according to the present account you would be spatiotemporally connected to the faraway building by having a practical, sensorimotor knowledge of the set of implicit rules of interdependence between visual stimulation from the building and your own movement as you actively interact with it. This would be manifested, for example, in your expectations that if you walked far enough to one side while keeping the building in view, the building should be progressively occluded by is neighbour until you couldn’t see it anymore. And if you wanted to see it again, you would also expect that if you walked in the opposite direction the building would gradually come into view again, and so on. These expectations correlate with the feeling of spatiotemporal connection that is characteristic of object perception, which is missing in a perception of objects in a picture. As this account relies on practical, sensorimotor knowledge rather than processing by motion-guiding vision, it avoids the problems of Matthen’s account. Ideally, we should be able to incorporate these insights without having to be committed to the more controversial claim put forward by the sensorimotor theory that mastering sensorimotor contingencies is all there is to perceiving objects. One promising proposal, which I’ll explore below, may be found in Evans’ claim that singling out an object demonstratively requires not only a perceptual relation to the object but also a capacity to locate the object in egocentric space Evans : . Although there’s been some controversy as to what this requirements amount to as I’ll explain below , I’ll suggest a way of understanding it that bears close relations to the element of spatiotemporal connection emphasized here: namely, as a practical, sensorimotor knowledge of

Mohan Matthen 

how to orient oneself in relation to the object, manifested in perceptual expectations and anticipations in relation to the object’s behaviour in space and time. As this spatial element is introduced in Evans’ theory to complement object perception rather than as an attempted reduction of what object perception amounts to, we might be able to incorporate this spatial element without being committed to the more controversial claim put forward by the sensorimotor theory.

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Spatial significance

Evans’ requirement that the subject be able to locate the object in egocentric space if she is to think demonstratively about it has been subject to some controversy. This controversy, however, rests on a misunderstanding. Perhaps because of Evans’ excessive emphasis on the epistemologically demanding principle that one could not think of an object without knowing which object one’s thought concerns, many of his critics and commentators have interpreted him as defending the thesis that for a subject to have a demonstrative thought about an object, she is required to know which particular location the object actually occupies in space. Both Campbell and Peacocke , for example, propose alleged counter-examples to Evans where a subject fails to have knowledge of the object’s actual position due to a misperception of its location, but where we are nevertheless inclined to admit she is in a position to have a demonstrative thoughts about it. As Peacocke writes: W e can imagine at some fairground stand an apple, seen in a mirror which is amongst various other moving mirrors: the set up may be so complicated that it is beyond the subject to locate that apple in egocentric space. But it seems that he can still think about it, wonder where it is now, and so forth. Peacocke : -

In a similar vein, Campbell argues that Evans’ alleged theory implies that if you make a mistake about the location of the object, you are not in a position to refer to the object at all. So you cannot refer demonstratively to an object which you see through a prism that you do not know is there” Campbell : . Campbell’s conclusion, which he takes to be a refutation of Evans’ theory, is that this view has no plausibility at all. It implies that you cannot even think  Evans calls this requirement ‘Russell’s Principle’, which he defends at length throughout his ‘The Varieties of Reference’ .

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demonstratively about an object you can see perfectly well, because you are subject to some illusion about its location ibid. . Both of these counterexamples miss the point, as Evans never required the subject to have knowledge of object’s actual location in space. Although Evans indeed talks in terms of the subject having to ‘locate’ the object, he is careful enough to discuss counter-examples similar to those proposed by Campbell and Peacocke, and explicitly warns the reader not to understand him as requiring the subject to have knowledge of the object’s actual position in space. The following passages are especially clear in this respect: In a great many cases a subject may make a demonstrative identification of an object without actually knowing where it is. The information-link with the object may enable the subject effectively to locate the object without providing very specific information about its location – for example, when one is able to home in upon the beetle eating away in a beam. … In such cases we are placed in a position in which we have the practical ability to locate the object. Evans :

This passage is followed by a footnote where Evans anticipates Campbell’s counterexample, involving a case where the subject is wearing prisms that cause him to misperceive the location of the object: Another case of this kind arises when the subject wears prisms which distort his field of vision – either shifting it to one side or inverting it. In such a situation the subject can give no definite location to an object in egocentric space. 0evertheless he can be said to know which object is in question – as long as he keeps his eyes on it – because he has an effective method for locating the object. ibid.

Thus, we need not insist on the idea that locating the object for Evans means having knowledge of the object’s actual position in space, as many of his critics have supposed. As the passages above make clear, the crucial idea is that one should have a method , a practical ability to locate the object in egocentric space. But the problem is that Evans never really elaborates on what this practical ability amounts to, other than in terms of vague metaphors like a fisherman who knows how to locate a fish by feeling it tugging at the other end of his fishing line, even if he cannot give an answer as to the fish’s precise location ibid. . Sure, if we had an actual fishing line connected to an object, we would only need to follow the line to the end in order to locate the object; but this metaphor is quite unhelpful in the case of ordinary perception. One possibility, following suggestions by Cussins and Grush , is to explain one’s practical ability to locate the object in space in terms of a

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practical, sensorimotor knowledge of how to orient oneself in relation to the object’s perceived location, in order to perform various actions in relation to it. This knowledge is supported by our mastering a set of sensorimotor contingencies which govern the behaviour of three-dimensional objects in threedimensional space, acquired through repeated patterns of interactions with objects in the world, and manifested in our perceptual expectations and anticipations as we actively interact with the object as explained by the sensorimotor theory above . This allows us to credit the subject with a practical ability to locate an object in space even if the object happens to be distant like the building , or even if its perceived location turns out to be illusory as in Peacocke’s fairground example . In the fairground case, one’s practical knowledge would be manifested in one’s perceptual sensitivity to the ways in which one’s movements vary in certain systematic ways with one’s experience of the apple. As long as one had such dispositions concerning the apple’s perceived location, one could be said to have a practical ability to locate it. With these ideas in mind, we can say that when a subject has a practical ability to locate the object in space, the object will have ‘spatial significance’ for the subject, where for an object O to have spatial significance for a subject S means that O’s perceived location is the location the subject is disposed to orient herself towards in order to act upon the object. These dispositions are manifested in one’s perceptual expectations and anticipations in relation to the object’s behaviour as one actively interacts with it, and correlate with the feeling of spatiotemporal connection that is characteristic of genuine object perception. In short, the suggestion is that for a subject to have a feeling of spatiotemporal connection in relation to O is for O to have spatial significance for the subject. Real three-dimensional objects perceived in a three-dimensional space have spatial significance, while objects depicted in a picture do not. To conclude, I agree with Matthen’s observations that we can only select objects to which we are spatiotemporally connected, something our theory should be able to accommodate. But rather than following Matthen’s lead and taking the feeling of spatiotemporal connection to be a phenomenological consequence of processing by motion-guiding vision, my suggestion is to account for it in terms of the object acquiring spatial significance for the subject, manifested in perceptual expectations and anticipations that govern our active engagements with objects in space. This is so even if the object is perceived at a distance or illusorily through mirror arrangements. In order to incorporate these observations into our theory I propose we acknowledge a third constraint on object representation, besides the constraints of individuation and maintenance of numerical identity introduced in chapter

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one. )or if we can only single out objects that have spatial significance for us, this leads us to posit a spatial significance constraint on object representation, something that any putative theory of object representation must be able to elucidate. In other words, in order to explain our capacity to represent particular objects we need to meet the following constraints: . Individuation: singling out something as an object requires one to be able to spatially discriminate the object from its neighbours and from the background. . Maintenance of 0umerical Identity: singling out something as an object requires one to keep track of its spatiotemporal trajectory, continuously representing it as the same object through time and motion. . Spatial Significance: singling out something as an object requires the object to have spatial significance for one. After critically engaging with a number of attentional and non-attentional theories in chapters four and five, we are finally in a position to put forward a perceptualist theory of demonstrative thought, which seeks to meet these constraints in the following manner: . Individuation: it is the function of object-centred segmentation processes to parse the visual array into discrete but unstable perceptual elements proto-objects , which are the units of visual attention Vecera . . Maintenance of 0umerical Identity: once attention is allocated to one of these proto-object representations, it will endow it with greater spatiotemporal coherence, allowing it to retain its numerical identity in time Rensink . . Spatial Significance: part of what it is to perceive an object is also to have a practical, sensorimotor knowledge of the object’s behaviour, acquired through patterns of interactions with objects in the world and manifested in one’s perceptual expectation and anticipations in relation to the object as one actively interacts with it Evans , O’Regan & 0oë . These three elements, according to perceptualism, jointly explain how perception puts us in a position to have thoughts about objects in our external environment. So whenever I refer to a perceptualist theory of demonstrative thought in the course of this book, this is the theory the reader should have in mind: one that explains singular object representation at the more primitive level of perception, structured in terms of the three elements above. In the next chapter, however, I will introduce ‘the conceptualist challenge to perceptualism’, which calls for more sophisticated forms of conceptual un-

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derstanding of what objects are and how they behave in order for object representation to be possible. This challenge, as we will see, raises serious difficulties to the theoretical project of accounting for object representation at the more primitive level of perception. It will then pave the way for the ‘pragmatic view of demonstrative thought’ to be introduced in subsequent chapters, where a pragmatist approach to object representation will be proposed as way of moving beyond perceptualism while remaining at the level of preconceptual cognition.

5 The Conceptualist Challenge to Demonstrative Thought 5.1 Introduction: the story so far Before introducing the conceptualist challenge, it might be useful to recapitulate our progress so far. We began our investigation with the task of explaining our capacity to have demonstrative thoughts about particular objects in our external environment. I proposed in chapter one to understand this as a capacity to engage in ‘attention-based mental activities with singular demonstrative contents’. The main motivation behind this qualification was to move beyond the paradigmatic cases of demonstrative judgments and attributions of properties to perceived objects, and include cases like deictic imagination and visualization, spatial reasoning, and so on. These are all mental activities targeted at particular objects in one’s external environment. I have then introduced two broad approaches to the study of demonstrative thought: perceptualism and conceptualism. According to the first, demonstrative thought inherits its singular content from the singular content of perception. What the theorist needs to explain in this picture is how perception enables us to pick out particular objects in the world and puts us in a position to have demonstrative thoughts about them. This translates into an empirically oriented project that purports to show that there are perceptual mechanisms and processes that are naturally tuned to the tasks of individuating and tracking medium-sized material objects, independently of the application of concepts on the part of the subject. In contrast, conceptualism tells us that the singular element of our attention-based mental activities can only be elucidated in light of sophisticated background conceptual knowledge. For it is precisely this knowledge what allows us to distinguish individual objects from recurrent instances of features as the representata of our attention-based mental activities. In this picture, demonstrative thought cannot inherit the singular content of perception, since there’s no singular content to be inherited in the first place. On the contrary, singularity comes from above, from a conceptual understanding of what objects are and how they behave in space and time. In chapter two I have distinguished two forms of perceptualism: attentionbased and non-attentional, depending on the kind of perceptual mechanism posited in the account of object selection and representation. Chapter three was then dedicated to a critical discussion and exposition of attention-based percep-

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tualism, as proposed by John Campbell (2002), Wayne Wu (2011a/b), and James Stazicker (2012). The theory we ended up with at the end of chapter was roughly like this: At a first stage, particular acts of conscious attention set in motion certain subpersonal perceptual processes that pick out objects in the world. As a result, the subject becomes aware of a perceptual (nonconceptual) singular demonstrative content. Once an object has been selected and perceived in this manner, we may then say that the subject is in a position to have demonstrative thoughts about it. In the present theory, this was cashed out in terms of the subject ‘cognitively attending’ to the object in question, a capacity that exploits mechanisms of perceptual attention but that differ from it insofar as cognitive attention makes the subject aware of a different content – a content with conceptual structure, which allows the subject to have conceptually structured thoughts of the form ‘this (x) is F’, where the content of the demonstrative ‘this (x)’ is inherited from the singular content of perception. We can capture the basic elements of this theory with the following schema:

Fig. 17: Relation between cognitive and perceptual attention

In chapter four the underlying perceptual bases of this theory were called into question, on the grounds that attentional processes presuppose that objects have already been selected and represented at a pre-attentive level. After reviewing some candidates for what these pre-attentive processes of object selection could be, the most plausible candidates were object-centred segmentation processes, as suggested by Raftopoulos (2009a,b). There was, however, one fundamental problem with this proposal. Although these processes function to individuate perceptual elements (called ‘proto-objects’) in a visual array, they fail to maintain the numerical identity of these proto-objects in time. Without the allocation of attention, proto-object

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representations have no spatiotemporal coherence, quickly decaying after a few hundred milliseconds and being immediately replaced whenever a new stimulus appear at the same retinal location where a proto-object had been previously represented (as shown by Rensink 2000). As one constraint of object representation is maintenance of numerical identity, object-centred segmentation processes fail to explain how objects are selected and represented at the more primitive level of perception. Maintenance of numerical identity requires the allocation of attention, which endows volatile and unstable proto-object representations with greater spatiotemporal coherence. Of course, this is not to say that there is no role for object-centred segmentation processes to play in a perceptualist theory: after all, they determine the units of visual attention by parsing the visual array into (unstable) perceptual elements to which attention may be allocated. To capture the contribution of both pre-attentive and attentive elements to object selection and representation, I sketched a hybrid perceptualist theory in chapter four, which combined insights from both groups of theories. At the bottom level, object-centred segmentation processes parse the scene into discrete perceptual elements (protoobjects), which are the basic units of visual attention. Once attention is allocated to one (or a few) of these proto-objects, they are endowed with greater spatiotemporal coherence, thus allowing the subject to perceive them as individual objects that retain their numerical identity in time. As we also reviewed evidence that the allocation of attention brings with it the involvement of higher cognitive centres in the brain (as argued by Lamme 2003), the distinction between perceptual and cognitive attention can no longer be maintained. All forms of attention are cognitive in nature, whose basic function is to put visual information “into the context of the systems' current needs, goals and full history”, as Lamme puts it (2003: 16). But acknowledging this fact does not mean abandoning the prospects of a perceptualist theory of demonstrative thought. In this hybrid theory can we still explain how objects are picked out in the world and represented at the more primitive level of perception, independently of the application of concepts. As suggested by Rensink, attention endows proto-objects representations with greater spatiotemporal coherence merely in virtue of allowing these representations to enter visual short-term memory (2000). This partly explains how one may be in a position to have demonstrative thoughts about the attended object. There was, however, a different kind of challenge to this theory. As Mohan Matthen argues (2005/2012), there is an important element of object perception that the hybrid theory above leaves out: the objects which we perceive, attend to, and think about, are felt as perceptually present in our external environ-

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ment, as things we can physically manipulate and act upon. This feeling of perceptual presence – or, to put it in our current terminology, of spatiotemporal connection – is characteristic of genuine object perception, and is absent, for example, in a pictorial depiction of objects. As processes of object segregation and visual attention are also at work in our perception of objects in a picture, they don’t fully explain how is it that the objects we perceive and think about are felt as spatiotemporally connected to us. This feeling of spatiotemporal connection, as argued by Matthen, is best understood through the idea of real three-dimensional objects having egocentric locations for the subject. What this means is that perception presents us with objects as in certain distinctive spatial locations, in our hic & nunc, which allows us to cognitively engage with them in various ways. Following Evans’ lead (1982), I have suggested that what it means for an object to have an egocentric location is that its perceived location acquires spatial significance for the subject. In Evans’ theory, an object acquires spatial significance for a subject insofar as its perceived location is the location the subject is disposed to orient herself towards in order to act upon the object. As both Evans and Matthen rightfully noticed (albeit in very different ways), our capacity to single out objects in the world and think demonstratively about them is partly explained by the way in which these objects acquire spatial significance to us. Objects in a picture, which lack spatial significance, cannot be singled out as objects (as opposed to regions on the surface of a picture). Nevertheless, I have also argued that Matthen’s suggestion to explain spatial significance in terms of processing by motion-guiding vision ultimately fails. Although this suggestion seemed promising for objects in near space, it could not account for the fact that objects beyond near space also have spatial significance to us. An alternative suggestion is to explain their spatial significance in terms of our practical knowledge of a set of sensorimotor contingencies that govern the behaviour of three-dimensional entities in a three-dimensional environment (Noë & O’Regan 2002). This will give rise to certain perceptual expectations and anticipations in relation to a perceived object, which control our dispositions to orient ourselves in certain ways in order to act upon it. These expectations, I suggested, correlate with the feeling of spatiotemporal connection. Real three-dimensional objects, embedded in a three-dimensional environment which we also occupy, will give rise to these expectations, while objects depicted in a picture will not. The upshot of this discussion was a new kind of perceptualist theory, whose basic elements can be summarized in the table below:

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Tab. 1: Basic elements of a perceptualist theory of demonstrative thought

Individuation

Pre-attentive processes of object segregation (Vecera 2000)

Maintenance of Numerical Identity

Attentional Selection (Rensink 2000)

Spatial Significance

Practical sensorimotor knowledge of the behaviour of three-dimensional objects in a three-dimensional environment (Evans 1982, O’Regan & Noë 2001)

Once an object has been selected in this manner, the subject is then in a position to have demonstrative thoughts about it. The singular content of the subject’s demonstrative thoughts, as perceptualism claims, is inherited from the singular content of the underlying perceptual state, as explained by the set of perceptual processes and sensorimotor knowledge laid out above. So now we finally reach a position where the conceptualist challenge may be introduced. Some philosophers, as we shall see below, have complained that the elements posited by perceptualism are insufficient to explain how individual objects are represented by a subject. The conceptualist challenge to perceptualism is that perceptual processes and practical skills fail to differentiate between individual objects and recurrent instances of properties as the representata of one’s attention-based mental activities. Singularity, the conceptualist claims, comes from ‘above’, i.e., from higher cognition. It comes from a conceptual – and not merely practical – understanding of what objects are and how they behave.

5.2 The conceptualist challenge to perceptualism: preliminaries The main arguments behind conceptualism have their source in the writings of Strawson (1959) and Quine (1960). Strawson famously distinguished between a more primitive ‘feature-placing’ level of experience and a more sophisticated ‘particular-involving’ level, where individuals are first introduced in cognition. Roughly speaking, the idea is that to be in mental states with singular demonstrative contents requires a fairly sophisticated conceptual understanding of ‘objecthood’. For it is precisely this understanding what allows us to attribute singular content to the subject’s mental state, rather than a feature-placing content that merely captures her capacity to respond to recurrent instances of

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features. The contrast here is between a creature who, when perceptually confronted with a particular apple, is only able to recognize that it is once again in a situation where ‘appleness’ is present in its external environment, versus one that is able to grasp it is faced with a particular apple: an apple that might be numerically identical to one encountered in earlier occasions, and that might be encountered and re-identified again in the future. In the first case, the content of the creature’s representational state could be captured in terms of a feature-placing structure like ‘appleness’, or ‘appleness again’; particular objects are introduced in cognition only at a second, more sophisticated stage of cognitive development, when a set of background conceptual abilities allow it to grasp that the apple it perceives is a persisting, unique individual tracing its own history in the world independently of the creature’s own history. Only then it would be able to represent not only ‘appleness again’ but ‘this particular apple’. Without these background conceptual abilities the creature would not have singular demonstrative thoughts about objects, only about recurrent instances of properties. Even if it is able to engage in attention-based mental activities directed at what are in fact objects, these activities would not have singular demonstrative contents.1 This brand of conceptualism has been subject to severe criticisms in the past few decades, especially due to evidence from developmental psychology. A common strategy was to appeal to empirical evidence that show that visual systems are naturally tuned to the tasks of singling out and keeping track of medium-sized, three-dimensional volumetric solids (material objects). Moreover, that they have their own means of doing so, on the basis of spatiotemporal information retrieved from a visual scene in purely bottom-up ways, and processed according to operational principles that have been hard-wired into the system by evolutionary pressures. This suggests that perception presents with a world that is already carved up into discrete objects that maintain their numerical identity in time, independently of any conceptual understanding on the part of the subject. This capacity is already present since very early stages in cognitive development, more precisely at around 3.5 months of age as argued by developmental psychologists like Elizabeth Spelke, Susan Carey and Fei Xu.2

|| 1 Strawson 1959, ch. 7. See also Cussins 1992 and Bermudez 2003 for informative discussions on the ‘feature placing’ and ‘object-involving’ levels of experience. 2 Spelke et al. 1995, Carey & Xu 2001, Xu 2007. Other studies push this age back as low as 2 months (Hespos & Baillargeon 2001), but the precise age in which this capacity emerges is not important for present purposes.

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Take for example the experiment illustrated in figure 18 below, proposed by Spelke and collaborators (1995) and widely replicated ever since. In this experiment, qualitatively identical rubber ducks are presented to infants as coming out from behind spatiotemporally discontinuous barriers in alternating order, until the barriers are lifted at the end of the task. What they found is that infants are surprised (i.e., exhibit longer looking times) if the final outcome reveals only one object rather than two, which suggests that they are already able to use the spatiotemporal discontinuity between the two barriers as a principle of distinctness of numerical identity. If they were only able to recognize recurrent instances of features (‘rubber duck-ness again’), the prediction would be that they would not be surprised at the unexpected outcome, as they would be unable to distinguish one individual rubber duck from another.

Fig. 18: Experimental design for object individuation in early infancy (from Carey & Xu 2001)

Indeed, this is exactly what happens when instead of cohesive objects they are presented with non-cohesive ‘stuffs’ like sand poured behind the screens, in which case they fail to be surprised at the unexpected outcome (Huntley-Fenner et al. 2002). But the experimental results of Spelke et al. clearly demonstrate

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that spatiotemporal information alone can be used as means to draw a distinction between numerical and qualitative identity of bounded cohesive objects (like rubber ducks), independently of the more sophisticated forms of conceptual understanding posited by conceptualism. But before we proceed, a word of clarification: developmental psychologists like Susan Carey, Elizabeth Spelke and Fei Xu repeatedly insist that infants’ capacities in these sorts of experiments cannot be explained in purely perceptual terms, and that in order to explain these results we must suppose they possess the concept ‘material object’, which they use to infer distinct numerical identity in experiments like the one illustrated above (Spelke 1995, Xu 1997, Carey 2009). But if we must appeal to concepts in order to explain these results, wouldn’t this be a vindication of conceptualism after all? Not at all; as I shall clarify in the course of this chapter, I call ‘conceptualism’ theories that posit more sophisticated forms of conceptual understanding in order to explain singular demonstrative thought, such as the capacity to represent objects in a comprehensive, so-called ‘objective’ spatiotemporal framework. Therefore, as long as the Carey/Spelke/Xu view does not appeal to these forms of conceptual understanding in its account of object representation, it would not be a conceptualist theory. But in spite of the empirical evidence against conceptualism, it has made something of a comeback in recent years. In particular, psychologist Gary Hatfield (2009) has revived the Quine/Strawson position concerning object representation, and proposed a way to explain the experimental results above without appealing to singular object representations. As Hatfield’s theory establishes a more direct dialog with the perceptualism, in articulating the conceptualist challenge I will mainly focus on Hatfield’s brand of conceptualism, rather than on the original arguments by Strawson and Quine. But I fully acknowledge the origins of these arguments, and I will resort to these philosophers whenever further clarification is needed. To understand how the conceptualist challenge is posed in Hatfield’s theory, we can start with his own account of what it is to perceive particular objects. To begin with, Hatfield is happy to grant that the perceptualist has correctly identified two necessary components of object perception: segmentation processes and attentional selection (Hatfield 2009: 235-8). The job of segmentation processes is to determine from the initial retinal image which elements combine with which elements in order to form a single spatial structure, and which elements combine in order to form other structures. Borrowing elements from Ken Nakayama’s theory of surface representation and perception (Nakayama et al. 1995), Hatfield agrees with the perceptualist claim that visual perception deliv-

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ers a world that is structured into multiple perceptual elements segregated from one another, which retain their identity through time and motion. These elements form a middle-level perceptual representation Nakayama et al. call ‘surface representation’. As the authors put it: It is a general purpose, intermediate representation in that it codes enduring aspects of our physical world (…). This surface level determines whether surfaces are seen as connected or disconnected; folded, straight or curved; whether they pass in front or behind; whether they are transparent or opaque. Nakayama et al. 1995: 9-10

Nakayama says that these segregated spatial structures also attract attention, retaining their identity in time for as long as attention is maintained upon them (1995: 40-5). This allows the subject to track these segregated structures through time and motion, making these surface representations functionally equivalent to the spatiotemporally coherent object representations posited in the perceptualist theory. This makes Hatfield’s brand of conceptualism substantially different from that proposed by more orthodox conceptualists like Quine, who thought for example that the world of the pre-linguistic infant was “one great blooming confusion”3 composed out of unstructured sensory primitives. As a consequence, Hatfield’s conceptualism is not so easily refuted by empirical evidence from developmental psychology. But even if these perceptual processes are able to distinguish perceptual elements in a visual array, Hatfield denies that these perceptual elements correspond to individual objects: “although perceptual segregation and attentional tracking of unified spatiotemporal regions put is into a perceptual relation with things that are in fact objects,” he writes, “they do not by themselves achieve object content” (Hatfield 2009: 237). The reason is that these processes are indifferent to the distinction between individual objects and repeatable, countable instances of property-kinds. Therefore, we have no reason to choose the former candidate over the latter as the representata of these perceptual representations. To illustrate, take for example the case of a subject who is perceptually presented with a cube next to a sphere. As we’ve seen, object-centred segmentation processes will segregate these shape-volumes from the background, and the allocation of attention will endow these representations with greater spatiotemporal coherence. As a result, we now have two segregated spatial structures – || 3 This expression comes from James (1890/1981: 496).

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two distinct shape volumes that are represented as having certain sizes and as bearing certain spatial relations to one another. Now suppose that at a later time the subject is once again confronted with a cube next to a sphere. As before, her perceptual system will segregate these shapes from the background and attentional processes will endow them with greater spatiotemporal coherence. As a result, we have a representation of certain spatial structures represented in the same way as before: as having certain sizes, certain shapes, and as bearing certain spatial relations to one another. But what makes us say that these structures represent an individual cube and an individual sphere, which may be identical to, or distinct from, the individual cube and sphere previously represented by the same (type of) spatial structures? Hatfield draws attention to the fact that that there is nothing in the representation of these spatial structures that allows us to settle that question, so the ascription of singular content to the perceptual states that represent them is unwarranted. Rather, what the subject’s perceptual system represents in each occasion are ‘abstract particulars’: spatial structures with certain shapes and sizes that bear certain local spatial relations, and that could be instantiated by any number of individuals in the world. What they represent, in short, are repeatable instances of a property-kind: more specifically, the property-kind ‘spatiotemporally coherent segregated spatial structure’: countable, spatially differentiated three-dimensional shapevolumes that have been recovered from the scene by our perceptual systems, and that may be continuously represented for as long as attention is maintained upon them.4 These spatial structures achieve the status of object representations only if coupled with the appropriate background conceptual knowledge of what objects are and how they behave. Here’s Hatfield: Representing objecthood, as it happens in adult perception, requires added content. At a minimum, it requires perceiving [objects] as individual material objects (not as mere local collections of properties), including the background knowledge that garden-variety objects (…) occupy distinct spatiotemporal locations (…) throughout their existence as [objects]. Hatfield 2009: 241

|| 4 Hatfield refers to this property-kind as ‘bounded trackable volume’ (2009: 243). But for present purposes we may stick to the functionally equivalent version ‘spatiotemporally coherent segregated spatial structure’, which highlights the role of both pre-attentive and attentional processes in generating these representations.

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What Hatfield emphasizes in this passage is that objects exist in space and time independently of our perceptual encounters with them, tracing their spatiotemporal histories in the world independently of our own history. Their histories, of course, may overlap ours from time to time, and we might then reidentify an object as the same individual we have encountered before. Representations of instances of property-kinds, on the other hand, are construed anew at every perceptual encounter, fading away as soon as the perceptual encounter comes to an end.5 In order to differentiate instances of property-kinds from individual objects we need “added content”, as Hatfield puts it, which takes the form of background knowledge of what objects are and how they behave in space and time. Once this background knowledge is coupled with perceptual representations of spatiotemporally coherent, segregated spatial structures, we may then assign the subject’s mental state a singular content: one that represents individual objects in the world. But in the absence of such background knowledge, there is nothing in the representation of these spatial structures we can appeal to in order to differentiate between individual objects and instances of propertykinds. In this case, a simpler content structured only in terms of the latter would do just as well. We must be careful with Hatfield’s claim that there is nothing ‘in the perceptual representation itself’ that allows us to decide whether it represents individual objects in the world. The point is not that there must be a representational element in the content that fully specifies that what is being represented is a unique, persisting object that occupies a distinct spatiotemporal location throughout its existence. Hatfield is careful to point out that ‘being a unique, persistent material object’ does not contribute to perceptual content in a descriptive manner, by being explicitly represented in that content and then applied to the object (2009: 249). Rather, for a perceptual representation to be a representation as of an individual object, it must be accompanied by a background conceptual understanding of what objects are and how they behave: that they are unique, persistent, potentially re-identifiable entities, and so on

|| 5 This is different from saying that these representations fade away as soon as the subject no longer receives any visual stimulation from objects in the scene. It is a well-known fact in cognitive psychology that object representations can be sustained in visual short-term memory for a period of time, even if the object briefly disappears behind an obstacle (more specifically, for 8 seconds according to studies conducted by Noles et al. 2005). The point here is that these representations fade away when one’s perceptual interactions with the object have ceased: when one loses interest, for example, and turns one’s attention to something else.

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(2009: 248). But these conditions need not be explicitly articulated in the content. What such background conceptual understanding consists in will be the subject matter of much of what lies ahead, but before we explore this question it might be worth touching on an important point about representational content that Hatfield’s conceptualism brings to light. The point, briefly mentioned in chapter one, is that there is an important epistemic dimension to singular content that perceptualism leaves out. We assign representational content to mental states in order to capture (among other things) the way the subject of the mental state represents the world, i.e., to mark certain psychological and epistemic capacities on the part of the subject. So the elements we assign to representational content, as well as the way in which they are combined, should reflect the way the subject grasps the structure of her external environment. In assigning singular demonstrative content to a subject’s mental state, for example, we are ascribing to this subject a capacity to apprehend her external environment as structured into individuals, and not just instances of propertykinds: that the thing the subject is cognitively engaged with is a unique, persisting individual that has come into existence before her encounter with it, and that will continue to exist after the encounter has ceased. But if the subject shows no signs of such psychological and epistemic capacities, the ascription of singular content is explanatorily idle. The capacity to perceive spatially differentiated spatial structures and perceptually track them through attention, for example, may be easily captured by a content structured in terms of abstract particulars or instances of property-kinds. In short, what we want to explain with a theory of demonstrative thought is not only how visual systems manage to segregate spatial structures in a visual array (which is a question for empirical psychology), but also how we as subjects of experience manage to apprehend our external environment as structured into individuals, over and above segregated spatial structures. Here’s where the theoretical notion of singular content, as applied to mental states, is particularly useful as a way of marking these capacities. But what is involved in apprehending one’s external environment as structured in this manner? What cognitive abilities are required, and how are they manifested? What is it for our thought to track individuals as opposed to instances of properties? These questions bear on the very relation between the metaphysics of objecthood and object-involving mental phenomena, and can be captured by the following principle put forward by Christopher Peacocke: If an account of what is necessarily involved in something’s having a certain property makes reference to some substantial condition which must be met by things which have

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it, a thinker’s mental representation of that property must be suitably sensitive to the existence of this substantial condition. Peacocke 1993: 171

So if we say that it is constitutive of something being an individual object that it is a unique entity that persists in time independently of our cognitive engagements with it, then for a subject to be able to represent individual objects she must be “suitably sensitive” to this property of objects. Otherwise, we would not be able to distinguish the subject representing an individual object rather than something like the property-kind “spatiotemporally coherent segregated spatial structure.” And what the conceptualist is claiming is that being “suitably sensitive” to the persistence of objects requires some fairly sophisticated conceptual understanding of what objects are and how they behave. To make this point clearer, let’s take Spelke et al.’s rubber duck experiment once again. Suppose that Mary, a 3.5-month old infant, behaves in this experimental setting in the usual manner. That is to say, she exhibits longer looking times at the unexpected outcome, relative to the expected one (see fig. 18 in page 145 for details). From Mary’s behaviour, we naturally conclude that she is able to use spatiotemporal discontinuity as a principle of distinct numerical identity: the object that appears from behind the first barrier is numerically distinct from the object that appears from behind the second barrier. Thus, we might suppose that in order to adequately capture Mary’s psychological and epistemic capacities we must assign a singular content to her mental state: more specifically, we should posit two distinct singular elements that represent objects a and b as they come in and out of occlusion behind the two barriers. Hatfield, however, argues that this conclusion is an example of what William James has called “the psychologist’s fallacy”, which is to confuse the psychological facts we are trying to study with the psychologist’s own perspective upon these facts (Hatfield 2009: 245). In ascribing singular content to Mary’s mental state we are needlessly importing the apparatus of adult (conceptual) cognition in order to explain something that can be easily explained in terms of more primitive psychological abilities. All Mary has shown us so far is a capacity to continuously represent the property-kind “spatiotemporally coherent segregated spatial structure” for a period of observation. Mary’s representational capacities are constrained by the requirements of her immediate actions and practical concerns, and bound to the context of her activity. There is no sign that Mary understands that the rubber ducks she perceives are unique, persisting individuals that have come into being before the experiment, and that may continue to exist long after it. So if we want to capture Mary’s psychological and epistemic capacities with representational content, the assignment of singular

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content to Mary’s perceptual state is explanatorily idle. A simpler content that mentions instances of property-kinds will do just as well. To conclude, we can now state the conceptualist challenge to perceptualism in the following terms: 1. Ascriptions of content seek to capture the psychological and epistemic capacities of the subject; in particular, ascriptions of singular content function to mark the subject’s capacity to apprehend her external environment as structured into individuals. 2. This capacity is manifested in the subject being suitably sensitive to certain constitutive features of individual objects, that differentiates them from other similar representata (such as the property-kind ‘spatiotemporally coherent segregated spatial structures’). 3. One constitutive feature of individual objects, which distinguishes them from instances of property-kinds, is that they continue to exist in space and time independently of our perceptual encounters with them. 4. So in order to be able to represent individual objects one needs to be suitably sensitive to the fact that objects persist in space and time. 5. This sensitivity requires background conceptual knowledge, since perceptual processes alone cannot explain our being sensitive to this property of objects; therefore, perceptualism must be false. What can we say about this? (1) and (2) are posited here as plausible features of content attribution, and will be maintained for present purposes. Although there may be other theories of content that do not rely on (1) and (2), I shall not discuss them here. One of the main goals of the pragmatic view is precisely to show how a pragmatist approach to singular representation can account for our capacity to apprehend our external environment as structured into individuals; for this purpose, I will work with the assumption that the theoretical role of singular content is to mark this capacity. This means that premises (1) and (2) will be accepted. (3), in turn, is taken from Hatfield’s observations, and posited as the constitutive feature of objects one is required to be sensitive to in order to distinguish individual objects from instances of property-kinds. (4) follows from (1), (2) and (3), which jointly support the anti-perceptualist conclusion stated in (5): ascriptions of singular content depend on the possession of a range of background conceptual abilities that cannot be explained at the more primitive level of perception. But perhaps here a perceptualist could object. Even granting, for the sake of argument, premises (1) through (4) above, the conceptualist conclusion stated in (5) does not necessarily follow from the premises. Although the conceptualist

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may be right in pointing out that perceptual processes of object segregation and attentional selection say little about our capacity to apprehend our external environment as structured into individuals, she hasn’t yet established that what explains this capacity must be background conceptual knowledge. For the perceptualist has already granted that these processes are indeed insufficient to tell the whole story about object representation. Her proposal was to supplement these perceptual representations with a practical – rather than conceptual – understanding of objects are and how they behave, a form of sensorimotor knowledge acquired through repeated patterns of interactions with threedimensional entities in a three-dimensional environment. Through these repeated patterns of interactions, the subject could come to have a practical understanding that objects are entities that persist in space and time. Even the 3.5 month-old infants in the rubber duck experiments already expect that an object that has been hidden behind an occluder continues to exist when unperceived, and that an object cannot move from point a (the first barrier) to point b (the second barrier) without passing through an intermediary point c (the space between the two barriers). These expectations mark the beginnings of a practical understanding of persistence and distinctness of numerical identity as constitutive properties of individuals. Why can’t we appeal to this practical understanding of objects in our account of singular representation? The conceptualist’s reply is that a practical understanding of objects’ behaviour is still insufficient to distinguish between individual objects and property-kinds. But in order to see why, we must first clarify the distinction between practical and conceptual knowledge that lurks in the background of the conceptualist challenge. What does it mean exactly for one’s knowledge – or understanding6 – of a certain subject matter to be practical as opposed to conceptual? Clarifying this distinction will be the main subject matter of the next subsection of this chapter.

|| 6 For present purposes I’ll use ‘knowledge’ and ‘understanding’ (of a certain subject matter p) as equivalent terms. Although distinguishing the two might be important for other theoretical purposes, nothing here will hang on this difference. We can thus safely take one’s practical/conceptual knowledge of a certain subject matter p (say, football) to be equivalent to one’s practical or conceptual understanding of it.

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5.3 The orthodox view of practical knowledge The distinction between ‘conceptual’ and ‘practical’ knowledge has obvious parallels with a long-standing debate on the distinction between ‘knowledgehow’ and ‘knowledge-that’ introduced by Ryle (1949). In Ryle’s famous rejection of what he called “the intellectualist legend”, he argued that practical knowledge or ‘knowledge-how’ is irreducible to knowledge of a set of propositions or ‘knowledge-that’: we may, for example, know very well how to perform some activity A (like playing football) without being able to articulate our knowledge as a set of propositions.7 Stanley and Williamson (2001), however, have criticized Ryle’s irreducibility thesis and argued for a reduction of ‘knowledge-how’ to ‘knowledge-that’. Stanley and Williamson’s argument is linguistic, and rely on semantic and syntactical analyses of the logical form of ‘knowing-how’ sentences. According to the authors, evidence from syntax and semantics support the view that these sentences must always take a propositional complement (2001: 426). This licenses the conclusion that a subject S knowing how to perform some activity A can be captured in terms of S having knowledge of a set of propositions. As formulated, this debate is more directly concerned with what sentences of the form ‘S knows how to p’ express, which is not exactly the same question that concerns me in this chapter. I am here concerned with the nature of practical knowledge, something that Stanley and Williamson’s linguistic analysis leaves untouched. For this purpose, the proposal that sentences of the form ‘S knows how to A’ should be analysed as the subject apprehending a proposition under a ‘practical mode of presentation’, as the authors argue, is hardly illuminating.8 What I propose, then, is that we approach this question from a different angle; one that affords us a more in-depth exploration into what is involved in a subject having a practical or conceptual knowledge of a certain subject matter p, regardless of whether these different forms of knowledge are captured by ‘knowing-how’ or ‘knowing-that’ sentences. A useful way to articulate this distinction is through an example originally proposed by Adrian Cussins (2003).

|| 7 Ryle 1949. See also Stanley & Williamson 2001, Snowdon 2003, Noë 2005 and Jung & Newen 2010 for reconstruction and discussion of Ryle’s anti-intellectualist argument from various points of view. 8 See Noë 2005 and Jung & Newen 2010 for criticisms of Stanley & Williamson’s notion of a ‘practical mode of presentation’ of a proposition.

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Suppose that you are driving through the streets of a big city, engaged in a series of driving-related activities: you brake at traffic lights, reduce your speed and change shifts in order to make the appropriate turns, check your rear view mirrors for incoming traffic, accelerate when circumstances permit, and so on. But now suppose that as you step deeply on the accelerator on an empty street, you are suddenly stopped by a policeman who walks up to your car and asks: “do you know how fast you were going?” Cussins notices that there are two ways in which the policeman’s question may be understood, corresponding to two different ways in which we may have knowledge of the speed in which we’re traveling. Here’s Cussins: On the one hand, I did know, and know very well, how fast I was traveling. I was knowingly making micro-adjustments of my speed all the time in response to changing road conditions. These micro-adjustments weren’t simply behaviors, the outputs of some unknown causal process. They were, instead, epistemically sensitive adjustments made by me, and for which I was as epistemically responsible as I was for my judgments. On the other hand, I did not know how fast I was traveling in the sense of the question intended by the policeman. I was unable to state my speed, in an epistemically responsible way, as some number of miles per hour. I knew what my speed was, but not as a speed. Cussins 2003: 150

The contrast Cussins is drawing in this passage is precisely that between practical and conceptual knowledge of the speed in which one travels. As the example illustrates, to have a practical knowledge of a speed like ‘80 km/h’ is for one to know this speed as a way of navigating one’s external environment, of orienting and adjusting oneself to changing circumstances as the activity unfolds in time. One manifests this knowledge in one’s own skilful actions as a driver, by taking a series of measures aimed at increasing driving stability and augmenting one’s chances of reaching a goal in a satisfactory manner. This means that one’s practical knowledge of ‘80 km/h’ is always relative to one’s own competence as a driver, where the speed is given to the subject in terms of certain subject-relative and task-relative affordances that are revealed as one engages in the skilful activity of driving a car in an urban environment. It’s a kind of knowledge whose content is better specified in terms of the set of sensorimotor skills one deploys in driving: a moment-by-moment manifestation of one’s competence as a driver, as one continuously adjusts and orients oneself in response to local changes. But now suppose that I had looked at the speedometer right before the policeman stopped me, and noticed that it registered ‘80 km/h’. This way of knowing about a speed, in units, affords me a conceptual knowledge of the speed in question. The speed is now given to me as some kind of object, which is inde-

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pendent of my own contingent characteristics as a driver or the driving task I happen to be engaged in. ‘80 km/h’ is something I can present to the policeman that will allow him to report my speed in a speeding ticket, and something that may be used against me in traffic court as a way of stating my speed from different perspectives and in a variety of different circumstances. To have a conceptual knowledge of a speed, in this sense, is to know it in a way that is essentially ‘portable’: something I can use in understanding what it is for other drivers who do not partake in my activity to drive at this speed, or what it is for me to go at this same speed in different circumstances – say, in a boat or on a (very fast) horse. Conceptualizing the speed as ’80 km/h’ allows me to refer to this speed in all these different circumstances as the same speed, regardless of the different ways in which I would be required to act in order to maintain the speed in each case. This is not so in the case of practical knowledge, which is ‘non-portable’: I may know ‘80 km/h’ as a way of driving my car through the streets of a big city, but not as a way of sailing a boat in the ocean or riding a horse on a race track. My knowledge of the speed in this manner is not something I can transpose to other situations in which I am not actually engaged in the driving task (Cussins 2003: 151). We can make this idea clearer through Campbell’s notion of ‘causal indexicality’ (1993/1994), which he employs as a way of characterizing two fundamentally different perspectives we may have upon the world. The first is practical and engaged, manifested in our interactions with objects in our external environment and described in terms of a ‘primitive’ physics vocabulary. The second is reflective and detached, constituting a disengaged point of view upon the world that is independent of our immediate practical concerns and described in terms of an ‘explicit’ physics vocabulary. These two vocabularies seek to capture the different ways in which we grasp the causal significance of our external environment. The vocabulary of a primitive physics is given in causally indexical terms. Causally indexical terms have similar properties to indexicals like ‘here’ or ‘now’ in that their reference varies systematically with context, except that with causally indexical terms the relevant parameters for fixing their reference are the causal powers of the subject. A good example is a predicate like ‘…is too heavy to lift’, which involves an implicit reference to the subject’s causal powers.9 In this case, the subject manifests her understanding that the property applies to an object in the way she reacts to the recognition that it applies. She || 9 ‘Implicit’ in that a creature need not have a concept of self in order to correctly grasp that the predicate applies. See Campbell 1994: 43-4.

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would manifest her understanding that the predicate ‘…is too heavy to lift’ applies to an object simply by ceasing her attempts to lift that object (Campbell 1994: 45). Campbell contrasts this way of understanding weight with that used in recipes, where objects’ weights are specified in units – 200g, 1 kg, and so on – which make no reference to causal powers of the subject. This specification of weight in units is characteristic of an explicit physics vocabulary, which makes reference to forces and masses that are independent of the causal powers of any subject in particular (Campbell 1993: 85). So if a creature grasps the causal significance of its external environment – i.e., the way mechanical notions such as force, speed, weight etc. apply to objects in its experience – only in terms of the environment’s affordances for the creature’s actions and navigation, then the representational content we use in order to capture its understanding of the world will be specified in causally indexical terms. In this case, the creature has only a ‘practical’ knowledge (or understanding) of what it is for something to weigh 40 kg or to travel at 80 km/h. To go back to Cussins’ example, my practical understanding that ’…is traveling at 80 km’ applies to me would be specified in causally indexical terms, involving an implicit reference to my driving skills and manifested in the microadjustments I am disposed to make in order to maintain this speed as my driving activity unfolds in time. In contrast, when I look at the speedometer and read ’80 km/h’ I acquire a ‘conceptual’ knowledge of my speed, whose content is specified in non-causally indexical terms (as ’80 km/h)’. It makes no reference to my dispositions or causal powers (or anyone’s, for that matter), or to the particular task I happen to be engaged in. In representing my speed as ’80 km/h’ I adopt a more reflective and detached perspective upon the speed in which I’m traveling, something I can apply to different subjects or to myself in different contexts. To conclude, the difference between practical and conceptual knowledge of a certain subject matter p may be captured in the following terms: Tab. 2: Contrast between practical and conceptual knowledge

Practical Knowledge of p

Conceptual Knowledge of p

Perspectival and context-bound: tied to the subject’s experiential awareness of p, manifested in the micro-adjustments she is disposed to make as responses to local changes

Objective and detached: can be accessed from different perspectives and in different circumstances, regardless of the subject’s activities and immediate practical concerns

Non-portable: cannot be applied outside the context of activity

Portable: can be extrapolated from the context of activity

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Causally indexical content: involves an implicit reference to the subject’s dispositions and causal powers

Non-causally indexical content: involves no reference to any particular subject’s dispositions or causal powers

I will call this way of drawing the distinction between practical and conceptual knowledge the orthodox view.

5.4 The conceptualist challenge revisited With this distinction in place, we are finally in a position to appreciate the full force of the conceptualist challenge to perceptualism. We wanted to know what kind of understanding of objects could supplement perceptual processes of object segregation and attentional selection, in order to provide an answer to the conceptualist challenge. The perceptualist’s suggestion involved a ‘practical’ understanding of objects, acquired through repeated patterns of interactions with three-dimensional objects in a three-dimensional environment: that objects continue to exist behind occluders, that they exert and are subject to forces as they come in physical contact with other objects, that they move in spatiotemporally continuous paths, and so on. But the problem is that according to the orthodox view, practical knowledge is non-portable and context-bound, with a content specified in causally indexical terms. To have a practical understanding that objects persist in time is to have certain perceptual anticipations and expectations concerning objects’ occlusions from the perceiver’s point of view, which guide the way she adjusts and orients herself in relation to a target object as obstacles get in the way. So if during a period of interaction with object x, x is temporarily hidden behind another object y, the perceiver would manifest her practical understanding that ‘x persists in time’ by expecting that if she walks around y or if y is removed, x will come into view again, or that if y starts moving back towards x, at the moment of collision y shall encounter some resistance, and so on. These ways of understanding persistence, however, always involve an implicit reference to the perceiver’s current expectations as the tracking activity unfolds in time. Once she disengages from the object and the activity comes to an end, these expectations will no longer hold, and she will no longer grasp that the predicate ‘…persists in time’ applies to the object. Therefore, she cannot apply this predicate to objects she is not currently engaged with, or to the same object in other (non-perceptual) contexts. It is a ‘non-portable’ knowledge of what objects are and how they behave, whereby the ‘object’ is given only as a

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way of interacting with one’s external environment. But in this case, it’s not clear that we are allowed to speak of an ‘object’ here at all. As Cussins puts it: (E)xperience presents looks-thus-and-so-and-reach-twist-and-graspable...ly, and that is not to present something (a thing) as a particular object which is, in principle, publicly available or identifiable from any perspective. If we attempted to give the content a referent, it would be a referent that was available only to the experiencing organism, and only when it was enjoying something like the present information-link. 'That is to say, it would be a necessarily local (and context-dependent) object, and hence no object at all. (Cussins 1992: 659

So even if we complement the perceptual processes posited by perceptualism with a practical understanding that objects persist in time, this would not meet the conceptualist challenge, as it would not be enough to differentiate individual objects from particular instance of property-kinds. The subject’s practical understanding of persistence would be tied to her anticipations and expectations as the objects she is currently engaged with briefly disappear behind obstacles, which cannot be applied to objects in other (non-perceptual) contexts. This suggests that what we need in order to distinguish objects from instances of property-kinds is a more sophisticated form of conceptual understanding of what objects are and how they behave: one that is ‘detached’ and ‘portable’, and whose content is specified in non-causally indexical terms. In this case, one’s understanding that the predicate ‘…persists in time’ applies to an object would not be tied to one’s current expectations and activities. It may continue to be applied to an object even after one’s interactions with it have ceased, or simultaneously applied to objects which one is not currently engaged with. Based on these considerations, we can now restate the conceptualist challenge to perceptualism with the extra premise (5), which purports to dismiss the perceptualist’s attempted reply: 1. Ascriptions of content seek to capture the psychological and epistemic capacities of the subject; in particular, ascriptions of singular content function to mark the subject’s capacity to apprehend her external environment as structured into individuals. 2. This capacity is manifested in the subject being “suitably sensitive” to certain constitutive features of individual objects, that differentiates them from other similar representata (such as the property-kind ‘spatiotemporally coherent segregated spatial structures’). 3. One constitutive feature of individual objects, which distinguish them from instances of property-kinds, is that they continue to exist in space and time independently of our perceptual encounters with them.

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4.

5.

6.

Therefore, in order to be able to represent individual objects one needs to be “suitably sensitive” to the fact that objects persist in space and time. To have a practical sensitivity to the fact that objects persist in time fails to differentiate between individual objects and instances of property-kinds. Therefore, conceptual capacities are required in order to account for singular object representation. It is not something that can be explained at the more primitive level of perception.

Now that we have the conceptualist challenge laid out before us, we can finally ask: what does it mean exactly to have a conceptual understanding that objects persist in space and time? How is this understanding manifested? What conceptual abilities are required for one to represent something as a unique, persistent individual, in a way that may be extrapolated to non-perceptual contexts, and how are these abilities manifested? One important idea behind conceptualism that is already present in Strawson and Quine is the requirement of reidentification. To say that objects are unique, persisting entities is to say that objects may be encountered at successive times and reidentified again as the same individual previously encountered, which has persisted from one encounter to the next. Without a capacity for reidentification, the very notion of persistence does not get a grip, as we would have no way to draw the distinction between numerical and qualitative identity across successive perceptual encounters. We wouldn’t be able to understand that this object we now encounter might be qualitatively identical to, but numerically distinct from, an object we have previously encountered and which continues to exist at a different location. But now we may ask: what, in turn, underlies the capacity to draw such a distinction? Here’s what Quine says about it: Distinguishing a body from an utterly similar one at a later time (…) requires acquisition of our whole schematism of space and time and the unobserved trajectories of bodies within it. A silver cup now viewed may be exactly similar to one viewed years ago without being the same one; and the original one may have tarnished and changed deceptively over the same period. Settling the question of identity would involve research and speculation about the movement of the [object] or [objects] in our absence. Quine 1995: 36

What Quine means by “our whole schematism of space and time” is what Strawson famously described as a unified, comprehensive and objective spatiotemporal frame of reference, where every place is simultaneously represented as

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uniquely connected to every other place (1959). Strawson thought that only a capacity to represent space in this manner could support what Quine refers to in the passage above as “research and speculation about the movement of the object or objects in our absence”, which are required for one to be able to reidentify objects across successive perceptual encounters, and thus understand that objects persist in time even after we have ceased our cognitive interactions with them.

5.5 On the idea of an ‘objective’ conception of space What is the relation between the capacity to represent objects and the capacity to represent space and spatial relations in a so-called ‘objective’ way? And what does it mean to represent space in this manner? Before we begin our discussion it might be useful to distinguish between two related although slightly different questions that the idea of an ‘objective’ conception of space might suggest. On the one hand, there is the question of what it is for a spatial representation to be structured in terms of an ‘allocentric’ or ‘egocentric’ frame of reference. Regarding this question, Robin Le Poidevin has suggested the following criteria for distinguishing egocentric and allocentric spatial representations (Le Poidevin 1999: 24-25): Tab. 3: Contrast between allocentric and egocentric spatial frames of reference

Egocentric reference frames

Allocentric Reference Frames

Centred on the subject’s body

Need not be centred on the subject’s body

Encodes perceptual information which is updated as the subject moves through space

Need not vary as the subject moves through space

Provides behaviourally relevant information of an immediate kind (i.e., it would immediately dispose a subject who wishes to reach for a visible goal to move towards it)

Does not provide behaviourally relevant information of an immediate kind; needs to be coupled with the appropriate demonstrative egocentric representations in order to become behaviourally relevant10

|| 10 On this last point see specially Perry 1979.

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The questions that concern me in the present discussion, however, are of a slightly different nature. I am here interested in our understanding of a unified space in the manner suggested by Strawson and Quine, where every place is causally connected to every other.11 What is involved in our grasping the interconnectedness of space in this manner? What constitutes our “whole schematism of space and the unobserved trajectories of bodies within it”, to put it Quine’s terms? What cognitive capacities underlie it, and how are they manifested? In this sense, the question of what exactly constitutes an allocentric or egocentric frame of reference need not directly concern us here, and may be left for another occasion.12 For even if we accept Le Poidevin’s distinction, this would not tell us what it is for one to understand the interconnectedness of space. We can start investigating our main question with an example proposed by Strawson, where he asks us to conceive of a very simple world of shapes such as that illustrated in figure 19 below. Given this shape world, Strawson asks: how is it that we are able to make sense of distinctness of numerical identity in this world? How, in other words, do we understand what it is for the top-left shape to be qualitatively identical to, but numerically distinct from, the bottom-right shape?

Fig. 19: Strawson’s shape world (from Strawson 1959)

|| 11 This is not to be confused with the metaphysical question about the absolute or relational nature of space, which is a different question altogether. 12 On this question see Le Poidevin 1994, Pacherie 2002 and Dokic & Pacherie 2006.

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As things stand, it is not very hard to make sense of this capacity. Each element in the shape world occupies a unique position in the world, and is uniquely related to every other element. And as the entirety of the framework is copresented with the individual shapes we are asked to distinguish, as soon as we are given the shapes we are also given their unique positions in the shape world. We know what it is for the top-left shape to be numerically distinct from the bottom-right shape because we can immediately grasp their unique positions in the framework that constitutes the shape world (Strawson 1959: 35). Notice that our representation of the framework of the shape world, as well as our representation of each of its individual elements, is perspectiveindependent. Every shape is individuated by its unique position in the framework and its unique relation to every other element in it. In this sense, the spatial representation of the shape world is ‘objective’. Every element is represented in the same way as every other (i.e., from no particular point of view), and the relations between every element are simultaneously represented. In this world there are no perspectival modes of identification such as “the top-left shape from my point of view”, for there is no particular point of view we can have upon this world or upon a subset of its elements. As soon as we are given the individual elements of this world we are simultaneously given the entirety of the framework that constitutes it, relative to which the notions of qualitative and numerical identity are made intelligible. Be as it may, our world does not seem to be in any way like the shape world. We cannot help but experience our world and the particulars that populate it from a certain point of view, from whatever idiosyncratic position we happen to occupy in the world at a given time. Moreover, differently from the shape world we are never given the entirety of our framework at once. We are given only parts of it at a time, and there is no single part of the framework that we perceive all of the time (Strawson 1959: 32). So given that this is how things are with us in the world, how is it that we understand the idea that an object we have encountered at a certain location at a certain time may be numerically identical to/distinct from an object encountered at a different time (and perhaps at a different location), if we are only given its position from a particular perspective? Strawson’s answer is that our representation of our spatial world is in some ways like the representation of the shape world. Although we are never given in perception the entirety of the framework at once, our representation of the spatial world nevertheless comprises “the idea of every material thing at any time being spatially related, in various ways at various times, to every other at every time” (Strawson 1959: 35). The reason we are normally able to make sense of

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distinctiveness of numerical identity in our world, and of the idea that objects may be uniquely identified and re-identified across successive perceptual encounters, is because we can represent space ‘objectively’, as it were, where places are represented in a single framework and identified in relation to every other place, regardless of the perspective we happen to occupy in the world. This allows us to understand that two things are numerically distinct because they are located at distinct places, much like the shapes in Strawson’s shape world. We can do that even if, unlike the shape world, we cannot perceive both places at once. We just have to employ a representation of space where every place is connected to every other, and individuated by their relations to other places in the framework (as opposed to their relations to the subject’s own position in it). This allows us to grasp distinctness of numerical identity independently of the perspective we happen to have upon the spatial world. The argument that emerges out of Strawson’s observations is this: to understand that objects persist in space and time in a way that is transposable to nonperceptual contexts, we must be able to reidentify individuals across successive perceptual encounters. This presupposes a capacity to draw a distinction between qualitative and numerical identity, i.e., to grasp what it is for this individual here now to be qualitatively identical to, but numerically distinct from, an individual previously encountered. As Strawson argues, we make sense of this distinction in terms of distinctness of spatial location: two objects are numerically distinct because they occupy distinct places. This capacity presupposes a single spatiotemporal framework, relative to which the distinctness of places can be made sense of. But as we can never be given the entirety of the framework at once, and cannot continuously track each element in the framework in relation to our constantly moving position, this framework must be represented in an ‘objective’ manner. As suggested by Strawson, what this means is that each place is represented as simultaneously connected to every other, which allows us to identify them – and thus grasp their distinct numerical identity – independently of the perspective we happen to occupy in the spatial world at a given time. This account ties our conceptual understanding that objects persist in time very closely to our capacity to represent space in an objective manner. So when the conceptualist claims that ‘background conceptual capacities’ are required for one to be able to represent individual objects, we should understand her as claiming that capacities for ‘objective’ spatial representation must be in place before we can engage in object-directed mental activities with singular demonstrative contents. In the absence of these capacities, we can only represent our external environment in terms of particular instances of property-kinds.

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Of course, this is not to say that once we are able to represent space ‘objectively’, we somehow transcend the inherent perspectival nature of our experience and come to perceive the world from “god’s point of view”, so to speak. Even when we come to represent space in an objective manner, the empirical world is never given to us in exactly the same way as the shape world, which is but a formal object to us independent of any perspective or embodied activity. Instead, what we learn when we learn to represent space in this manner is to place our perspectival experiences in a more objective and detached picture of the world, to understand that our experiences fit together with the experiences of others in a single story of the empirical world. As Strawson puts it, “this fitting together, this connexion, rests ultimately on relating the particulars which figure in the stories in the single spatiotemporal system which we ourselves occupy (Strawson 1959: 29).” When a place is represented in this manner, we no longer need to rely on perspectival modes of identification in order to identify it in the framework. The place may be a ‘here’ because it is the place we happen to occupy, but the identification and reidentification of this place no longer depends on our occupying it. For the place can also be identified in relation to other places in the framework, from whatever perspective we happen to have in relation to it. As Evans likes to say, when a place is represented in this manner we are no longer forced to introduce any ‘here’ or ‘there’ in the way we identify places (Evans 1982: 152). It should be noted, however, that Evans is not proposing an elimination of indexical terms here. For well-known reasons this would be a disastrous move, and the difficulties that would follow from an elimination of indexicals in specifying mental content are well documented in the literature.13 As Evans is careful to point out, the very idea of an ‘objective’ world is only intelligible because we grasp that the world we are modelling in objective terms is the very same world where we are situated as embodied agents, and, conversely, that the world we experience from our point of view is the objective world that is experienced by different agents from different perspectives (Evans 1982: 212). What Evans means to say is that once a place has been represented in an objective spatiotemporal framework, one has other means of identifying a place besides indexical means – one can identify it, for example, in relation to other places in the framework. Evans called these objective, “perspective-free” modes of identification fundamental Ideas of objects, which uniquely identify them by their so-called || 13 The reader is advised to check the stock of examples in Perry 1979, Castañeda 1966/1967 and Lewis 1979, among others in the massive literature dedicated to self-locating beliefs.

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‘fundamental ground of difference’ (Evans 1982: 105ff). The fundamental ground of difference of a place, for example, would be its unique spatial location. Fundamental Ideas are distinguished from non-fundamental Ideas which identify objects only from a certain perspective and relative to a point of view. An indexical way of identifying a place like ‘here’ would be a paradigmatic example of a non-fundamental mode of identification. A place represented in an objective spatiotemporal framework, in contrast, would be a fundamental identification of a place, which identifies it by its fundamental ground of difference, i.e., its unique position in the framework. Evans first introduces and motivates the notion of “Fundamental Ideas” in the context of our thought about abstract objects such as numbers, shapes or chess positions. As he puts it: An Idea of an object is part of a conception of a world of such objects, distinguished from one another in certain fundamental ways. For every kind of object, there is a general answer to the question ‘What makes it the case that there are two objects of this kind rather than one (…)? For example, we may say that shades of color are distinguished from one another by their phenomenal properties, that shapes are distinguished from one another by their geometrical properties, that sets are differentiated from one another by their possessing different members, that numbers are differentiated from one another by their position in an infinite ordering, and that chess positions are distinguished from one another by the positions of pieces upon the board. Evans 1982: 106-7

So when we think of a particular number – say, the number 27 – as the number occupying the 27th position in an infinite series of integers, we employ a Fundamental Idea of the number 27. But even if we happen to identify a number in a non-fundamental way, Evans says that our understanding of which number is in question must always rely on our knowledge of what it is for an identity proposition linking a fundamental and a non-fundamental Idea to be true. So if we happen to identify a place in an indexical manner (‘here’), our capacity to represent it as a particular place still must rely on our capacity to understand an identity proposition involving a fundamental and a non-fundamental identification of this place (Evans 1982: 151-2). We can make this idea clearer with an example. Suppose that you ask me ‘which number is the cube of three?’ and I reply ‘the number of countries in the European Union by the end of 2012’. This is a non-fundamental Idea of the number 27. But it is clear that if you are to understand my answer at all, that is, if you are to understand which number I have put forward as being the cube of three, you must be able to relate my non-fundamental Idea of this number to its fundamental Idea: you must know what it is for the identity ‘the number of coun-

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tries in the European Union by 2012 = 27’ to be true, which identifies this number as the number occupying a unique position in an infinite series of integers. But although the appeal to the fundamental ground of difference of a number might indeed capture something important about the way we think of numbers, the case is much less clear when it comes to our capacity to have thoughts about concrete spatiotemporal objects. When it comes to numbers, fundamental Ideas are clearly central to our thoughts about them, and a non-fundamental Idea such as ‘the number of countries in the European Union by the end of 2012’ seems clearly out of place as an answer to the question ‘which number is the cube of three?’ However, when it comes to the material objects that populate our external environment, it is non-fundamental Ideas that seem to pervade, such as demonstrative Ideas. If I want you to fetch me a cup that we both perceive, ‘fetch me that cup’ accompanied by a pointing gesture is a much more appropriate command than ‘fetch me the object at such-and-such global spatial coordinates’. In the case of material objects, what fundamentally distinguishes them from one another is their unique spatial location: ‘the object now at p’ would be a fundamental identification of an object, where p is the spatial position uniquely occupied by the object in a unified, objective spatiotemporal framework (Evans 1982: 171). But as demonstrative thought employs a demonstrative and hence non-fundamental Idea of an object, an explanation of our capacity to have demonstrative thoughts cannot be given in terms of our grasp of their fundamental ground of difference directly. It must always be given in terms of our knowledge of what it is for an identity proposition of the form ‘this object = the object now at p’ to be true. The left side of the identity captures the subject’s (non-fundamental) demonstrative identification of the object – her capacity to single out (what is in fact) an object in her external environment, which may be explained, following the perceptualist’s lead, in terms of three distinct elements: (1) Object-centred segmentation processes that individuate the object as a discrete perceptual element in a visual array, (2) attentional processes that endow the perceptual representation of the object with greater spatiotemporal coherence, and (3) practical sensorimotor knowledge which account for the object having spatial significance for the subject. The right side of the identity, in contrast, captures the object’s fundamental ground of difference: its unique position in a single, objective spatiotemporal framework. Knowledge of what it is for this identity proposition to be true seeks to capture one’s capacity to bring background conceptual knowledge to bear in one’s perceptual experience of the object in question: to understand that ‘there’,

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where the object is – the location which has spatial significance for the subject – is a unique location in a unified, objective spatiotemporal framework. This knowledge is what supports our understanding that the object in question is a unique entity that persists in time, individuated by its simultaneous relations to every other element in the framework. Knowledge of what it is for this identity proposition to be true, in Evans’ theory, amounts to a capacity to represent one’s egocentric space in terms of what is called in psychology a ‘cognitive map’ – an internal, mental analogue of a cartographic representation (Tolman 1948, O’Keefe & Nadel 1978). As Evans puts it, …a fundamental identification of a place would identify it by simultaneous reference to its relations to each of the objects constituting the frame of reference. A place would be thought about in this way if it was identified on a map which represented, simultaneously, the spatial relations of the objects constituting the frame of reference. (…) Our identification of places has this holistic character whenever we rely, in our thinking about places, upon what has come to be called a ‘cognitive map’: a representation in which the spatial relations of several distinct things are simultaneously represented. It is essential to the existence of a genuine concept of space, and of objects existing in space independently of perception, that the thinker have the capacity to form and employ representations such as these. Evans 1982: 151-2

When the subject is able to effect a coincidence between the egocentric space in which she moves and acts as embodied agent, and a cognitive map where this space is represented as connected to every other place in a unified spatiotemporal framework, the subject will be in a position to understand that this object is a unique individual that persist in time. As the main idea here is to elucidate the idea of one’s so-called ‘objective’ conception of space by appealing to the psychological notion of a cognitive map, I shall call this ‘the cognitive map strategy’. How well the cognitive map strategy will fare with respect to its promises will depend, of course, on the conceptualist’s ability to come up with a clear conception of what cognitive maps are supposed to be in the first place. What does it mean exactly to represent space in this manner? What is required for one to be able to form this type of spatial representation, and what evidence do we have for its presence in a subject? More importantly, in what sense do cognitive maps illuminate the idea of an ‘objective’ conception of space? In the next section of the chapter I will explore these questions in more detail, and raise some difficulties to the cognitive map strategy. My final conclusion will be that cognitive maps are unable to clarify the idea of a so-called ‘objective’ understanding of space, according to the conceptualist’s own criteria introduced in section 5.4.

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5.6 The cognitive map strategy (and its limits) The term ‘cognitive map’ was originally coined by psychologist Edward Tolman (1948) in order to explain rats’ behaviour in the context of spatial navigation tasks. Tolman used it to characterize a more comprehensive spatial representation of the animal’s external environment, where the paths, routes and spatial relationships it uses to navigate its environment are simultaneously represented. The essential feature of a cognitive map, in Tolman’s conception, is the ability to take novel shortcuts between two points that the animal has never taken before. As a consequence, when the animal represents its environment in terms of a cognitive map, “if the starting position of the animal [is] changed or variations in the specific routes [are] introduced, this wider [cognitive] map will allow the animal still to behave relatively correctly and to choose the appropriate new route” (Tolman 1948: 194).14 This contrasts with less sophisticated forms of spatial representations, where the animal’s environment is represented only in terms of a fixed path from its initial position to the goal. In this case, any variations in the landmarks that the animal has relied upon in order to learn its route will result in total disruption of its ability to navigate intelligently towards the goal. In Tolman’s classic ‘sunburst maze’ experiment, rats were trained to run the left-hand side maze (fig. 20) from an initial point A to a goal H where food was located, by passing through points B-C-D-E-F-G that led to the goal. Tolman then replaced the original maze with the ‘sunburst maze’ depicted in the righthand side figure, which blocked the animal’s original route and forced it to choose alternative paths that could lead to the goal. What Tolman found is that the vast majority of rats chose path number 5 which led directly to the goal, suggesting that they were able to represent the spatial relations between A and H independently of the particular route B-C-D-E-F-G they had previously learned as a way to that goal. This is evidence that rats have learned to represent their maze-environment in terms of a ‘cognitive map’ (Tolman 1948: 204).

|| 14 Compare with Evans: “This [fundamental] identification [of a place] has a holistic character: a place is not identified by reference to just one or two objects, and so the identification can be effective even if a few objects move or are destroyed”(Evans 1982: 151).

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Fig. 20: Tolman’s sunburst maze experiment (from Tolman 1948).

Perhaps the first difficulty in clarifying the notion of a cognitive map is that psychologists often employ this term in different ways, that are not always compatible with one another.15 Randy Gallistel, for example, uses ‘cognitive map’ to refer to any kind of spatial representation in the animal’s brain: “a cognitive map,” he tells us, “is a record in the central nervous system of macroscopic geometric relations among surfaces in the environment used to plan movements through the environment” (Gallistel 1990, quoted in Bermudez 2005: 29). So as long as the animal’s brain has some way of storing geometric information about noticeable landmarks in its environment for navigational purposes, this animal will have a cognitive map of its environment. Differently from Tolman, who posited cognitive maps as a more comprehensive form of spatial representation that is different in kind from single origin-goal representations, cognitive maps in Gallistel’s sense come in degrees: even the simpler ‘route’ representations posited by Tolman would be cognitive maps in Gallistel’s sense, differing from more comprehensive spatial representations only in the amount of information encoded.16 Faced with the multiple senses of cognitive maps, Bennett’s conclusion is that the term is hopelessly vague, and should be abandoned from serious cognitive psychology and ethology (Bennett 1996: 223). This may very well be true, but the issue need not concern us here. For even if the psychological community has not yet reached an agreement on how the notion of a ‘cognitive map’ should

|| 15 As Bennett 1996 points out. 16 See Bennett 1996 for a more detailed comparison between Gallistel’s and Tolman’s notion of cognitive map.

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be used, all that matters for evaluating the cognitive map strategy for present purposes is the way Evans proposes to use the term. As Evans explicitly refers to O’Keefe & Nadel’s theory of cognitive maps (Evans 1982: 151), when I talk of the ‘cognitive map strategy’ this is the sense of the term that the reader should have in mind, which I will attempt to elucidate below. O’Keefe & Nadel’s notion of cognitive maps bears close resemblances to Tolman’s original proposal. Similar to Tolman, O’Keefe & Nadel define ‘cognitive map’ in contrast with less sophisticated forms of spatial representation where only fixed origin-goal paths are represented. These simpler routes are computed by what O’Keefe & Nadel call the ‘taxon’ system of spatial representation, which uses simple learned associations between environmental stimuli and locomotor responses in order to create routes from starting points to destinations (O’Keefe & Nadel 1978: 96-101). The crucial feature of these routes is their non-flexible character: they provide a fixed line of movement from origin to goal, and the animal’s learning of these routes is an ‘all-or-nothing’ matter. In case there is any disruption in the landmarks that characterize the route, the animal’s capacity to navigate towards the goal breaks down, and it must learn another route from scratch. To illustrate with an example, if a rat in Tolman’s experiment represented its external environment through the taxon system alone, it would represent the spatial relation between A (origin) and H (goal) in terms of a fixed route characterized by a series of landmarks B-C-D-E-F-G. If this animal were to find itself in the sunburst maze, its performance would be at chance, choosing paths on a trial-and-error basis. Cognitive maps, in contrast, are the result of a much more powerful system of spatial representation. They may be understood as the mental analogs of cartographic representations, an internal representation of more noticeable landmarks in the animal’s environment which may be used to compute the shortest distance between any two represented points without the animal ever having travelled through those routes. The building of cognitive maps is the function of what O’Keefe & Nadel call the ‘locale’ system: a more powerful and flexible system of spatial representation which uses map-like representations of the environment in order to compute geodesic paths between locations (1978: 90-96). This allows different lines of movement to be computed between different points in space, making the animal’s navigational capacities more resistant to landmark alterations. Like Tolman’s cognitive map, this representation is different in kind from simpler routes computed by the taxon system. Cognitive maps contain larger amounts of information, and allow for much more powerful and flexible computations; but as a result, it also makes travel slower. Moreover, differently from the all-or-nothing learning and disruption process associ-

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ated with route representations, the animal’s learning of paths between points in a cognitive map is a gradual and flexible process, that is continuously improved and as the animal navigates its external environment. As in Tolman’s theory, evidence for cognitive maps can be found in the animal’s capacity to take novel shortcuts between two points in space. After all, from the way O’Keefe & Nadel set up the contrast between the taxon and the locale system, it is clear that novel shortcuts abilities cannot be explained in the former system. This system, as we’ve seen, represents origin-goal routes in an invariant and inflexible manner, and does not allow for novel pathways to be created ‘on the fly’ when landmarks are destroyed. So if we want to explain how the rats in Tolman’s sunburst maze experiment are able to choose route 5 as the shortest path to goal H, we must ascribe them a capacity to represent their maze environment in terms of a cognitive map, where every point is represented as simultaneously connected to every other. This allows the rat to compute that pathway number 5 is the shortest distance between A and H even if some landmarks happen to be destroyed. Indeed, many psychologists take novel shortcut abilities to constitute strong evidence for the presence of cognitive maps in animals. In Gould’s classical study of honey bees’ navigational capacities (1986), the insects’ ability to find novel shortcuts between two foraging sites was taken as conclusive evidence for Gould’s final conclusion that honey bees, contrary to what had been previously assumed, are able to form cognitive maps in much the same way as higher vertebrates. Peters (1973) also claims that an explanation of novel shortcut abilities observed in wolves’ hunting behaviour requires the concept of cognitive mapping, while Menzel (1973) makes a similar claim concerning chimpanzee’s movements and shortcutting abilities in the wild. This conception of cognitive maps ties possession of these spatial representations very closely to the animal’s capacity to use them in navigation. Even if this view remains somewhat controversial, we may safely take O’Keefe & Nadel’s theory at least as a well-established view on what cognitive maps are, which gives us clear criteria for attributing them to navigators. This view also seems close to what Evans had in mind, when he says that “nothing can be a cognitive map unless it can be used as map” (1982: 212), or that to have a cognitive map of the world is to have a capacity to “find one’s way about” in the world (1982: 162). To be capable, if one wishes to go to a certain destination (i.e., The High in Oxford) through a path one has never travelled before, of employing the following form of spatial reasoning: “if I am here between Balliol and the Bodleian, then that must be Trinity, and so the High must be down there” (ibid.)

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With these ideas in mind, we may state ‘the cognitive map strategy’ in terms of the following assumptions: 1. The idea of a so-called ‘objective’ conception of space may be elucidated through the psychological notion of a ‘cognitive map’, sensu O’Keefe & Nadel (1978) 2. In the relevant sense, a cognitive map is the mental analog of a cartographic map, i.e., an internal representation of one’s external environment where noticeable landmarks are simultaneously represented. 3. It is sufficient, for one to have a cognitive map, that one be capable of computing the shortest route between any two arbitrary represented places without having ever travelled through that route. There is, however, one serious problem with the cognitive map strategy. To see why, let’s grant, for the sake of argument, that one has the ability to form a map-like representation of one’s environment, which one may then use in order to compute geodesic paths between various represented locations. In what sense does this capacity elucidate the idea of a so-called ‘objective’ conception of space? The problem may be put in the following way: We have already seen (5.4) that the distinction between practical (egocentric) and conceptual (objective) understanding of a certain subject matter lies in the ‘causal significance’ one attaches to what is represented in this subject matter. In the case of objects, for example, to have a practical understanding of what objects are and how they behave is to assign significance to certain constitutive properties of objects in a causally indexical manner – in a way that involves an implicit reference to the subject’s dispositions and causal powers. A practical understanding that objects persist in time, in this case, would be given only in terms of subject-relative affordances, exhausted by one’s expectations and anticipations concerning the object’s behaviour as it is temporarily hidden behind obstacles. In contrast, to have a conceptual understanding of what objects are and how they behave is to assign causal significance to these same properties in a non-causally indexical manner. In this case, one’s understanding that the predicate ‘…persists in time’ applies to an object is no longer limited to one’s current engagements with it: the predicate may continue to be applied to an object even after one’s interactions with it have ceased, or simultaneously applied to objects one is not currently engaged with. But in order to understand that objects persists in time in this manner, the conceptualist required a so-called ‘objective’ conception of space: only this conception could support our knowing what it is for a currently perceived object

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to be qualitatively identical to, but numerically distinct from, a different object at a different place, which continues to exist unperceived. According to the cognitive map strategy, we can explain our objective conception of space in terms of a capacity to represent space with a cognitive map, sensu O’Keefe & Nadel: a mental analog of a cartographic representation where every place is simultaneously connected to every other. But now we arrive at a problem: we have just seen how one’s objective conception of a certain subject matter depends on the significance one attaches to what is represented in this subject matter. So even if we grant that a cognitive map is a representation that captures the interconnectedness of space – after all, it is a representation of space where, by definition, every place is represented as simultaneously connected to every other – the question we should be asking is this: how does the animal assign causal significance to the interconnectedness of the space it represents? And when the question is put in these terms, the limitations of the cognitive map strategy in elucidating the idea of a so-called ‘objective’ conception of space become evident. To be clear, what’s at stake here is not whether the cognitive map strategy can provide one with a grasp of space as interconnected, but what such a grasp consists in. According to the cognitive map strategy, possession of a cognitive map is tied very closely to our capacity to use these mental maps in navigation. This capacity in turn is manifested in our ability to compute the shortest distance between any two arbitrary represented places, which allows us to get anywhere we like from anywhere we happen to be. But this is precisely why the cognitive map strategy doesn’t deliver what it promises. For if we tie the ability to represent space with cognitive maps to our capacity to move in space, we haven’t yet left the level of causal indexicality, where our conception of space is exhausted by our practical abilities to navigate our external environment. In this sense, the simultaneous interconnectedness of space would be given to the subject only as a way of navigating her external environment, in terms of subject-relative navigational affordances which allows her to travel to any arbitrary represented place from anywhere she happens to be. But she remains unable to represent the spatial relations between any two arbitrary represented places independently of whether the subject herself is supposed to be at one of these places. For space to be interconnected, according to the cognitive map strategy, is just for the subject to be able to get anywhere she likes from anywhere she happens to be. As it is given to the subject in experience, this is only an egocentric space of action, and hence no ‘objective’ space at all according to the conceptualist’s own criteria.

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Therefore, we have to conclude that the cognitive map strategy is unable to deliver what it promised, which was to elucidate the idea of a so-called ‘objective’ conception of space. As Campbell puts it, It is because of the direct tie of the [cognitive map] model to action that the animal is confined to thinking of the spatial relations of places at which it itself might be, and to thinking in terms of geodesics, for example. So if the creature is to transcend all such limitations, it will have to think about the connectedness of its environment in a way that is not causally indexical. Campbell 1993: 87

Which leads us to another problem: what is it to think about the interconnectedness of space in a non-causally indexical manner? To be clear, the point here is not that the subject’s conception of space must make no provision about where the subject is and to where she’s headed. As we have already seen before (5.5), it would be wrong to equate our ‘objective’ conception of space with a capacity to ‘remove’ ourselves from the spatial framework where we act as an embodied agent. Rather, the relevant notion, as Evans argued, is that of knowing how to bring one’s egocentric space of action into coincidence with a unified spatiotemporal framework, where every place is represented as simultaneously related with every other. But the point under discussion is what such knowledge consists in and how it is manifested. If it’s just a practical ability to take novel shortcuts – as suggested by the cognitive map strategy – then we are still at the causally indexical level, where one’s conception of space is characterized only in terms of subjectrelative navigational affordances space provides. So in order to give substance to the idea of a so-called ‘objective’ conception of space, something else, in addition to what the cognitive map strategy can supply us, seems to be required. Something that allows us to transpose the level of causal indexicality and grasp the interconnectedness of space in a way that is genuinely independent of our activities and immediate practical concerns. But what would this ‘objective’ conception look like? The initial difficulty in characterizing it is that there are two opposing forces pulling us towards different directions. On the one hand, this conception of space cannot be characterized only in terms of subject-relative affordances: it cannot, therefore, be elucidated only by reference to the subject’s navigational abilities in her external environment. But on the other hand, our objective conception of space must, necessarily, involve our understanding that the space we model in objective terms is the very same space in which we act as embodied agents: it cannot, therefore, be a purely formal space like Strawson’s shape world, wholly disconnected from any possibility of perception and action.

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One promising proposal, developed by Campbell (1993), links our objective conception of space with our grasp of the possibility of movement by other physical objects in space. This proposal will be spelled out in more detail in the next section of the chapter.

5.7 Campbell on the role of physical objects in spatial thinking Suppose we start out with the idea that one way to register the interconnectedness of space is by registering its causal interconnectedness – that is to say, that the way things are at one place is causally dependent on the way things were at another place. Then, the question that is immediately raised is: how can we register the causal interconnectedness of space in a non-causally indexical way? The cognitive map strategy offered us a solution, but it was deemed unsatisfactory. The problem was that the way in which one registers the causal interconnectedness of space in the cognitive map strategy is tied too closely to one’s practical abilities as a navigator, exhausted by the possibility of one’s movements from one place to another. But notice that although the subject in that situation might be unable to grasp the causal interconnectedness of space in a non-causally indexical way, we, as observers from a third-person point of view, might be able to do so on this same basis. That is to say, by understanding the possibility of movement of the subject herself from one place to another, independently of our own movements, we can grasp the causal interconnectedness of space. This, in fact, is exactly Campbell’s proposal: through the possibility of movement by other physical objects in space, we come to assign causal significance to the interconnectedness of space in a non-causally indexical manner, which makes no reference to our own practical abilities as navigators (Campbell 1993). We can, in other words, grasp that the way things are at one place (where a certain object is now) is causally dependent on the way things were at another place (where the object was before), because the object has moved from one place to the other. But one qualification is in order: if the possibility of movement by other physical objects in space is going to fulfil this theoretical role, the space in which the object moves must not be wholly disconnected from our own. If we were watching, for example, a subject move from one place to another in a virtual reality environment, we could grasp the causal interconnectedness of the subject’s (virtual) space on this basis; but this space would be disconnected

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from our own, so this could not explain how we may come to have an ‘objective’ conception of the space we occupy, which is the question that concerns us here. But this problem is spurious, as it is not the case that we ordinarily appreciate other objects’ movements through space from no point of view. On the contrary, understanding that other objects move from place to place already involves an understanding that one of the places through which the object might pass is the place we happen to occupy, a place it might eventually return after venturing through other places causally connected to ‘this place here’. But notice that although we have now mentioned our own contingent position in space in an account of what it is to grasp the causal interconnectedness of space in a non-causally indexical manner, this is no threat to proposal under discussion. For what is giving substance to the way in which we assign causal significance to the interconnectedness of space is ultimately the possibility of movement by other physical objects. There is no mention of our own practical abilities as navigators, or, for that matter, of the moving object’s: we have said nothing about its capacities to find its way in space or to take novel shortcuts between places. We can explain our idea of objects moving in space merely through our grasp of certain principles of intuitive physics that govern their behaviour in a three-dimensional space: for example, that objects move independently from one another, that they follow continuous trajectories through space-time, that they are internally unified and exhibit internal causal connectedness, and so on.17 By grasping how these principles apply to objects on the basis of our interactions with them, we can understand that if we set a spherical object to roll down a mountainside, it will continue to roll until it reaches the bottom (as long as its path remains unobstructed), passing through a succession of places causally connected to one another; or that when the bird who nested on my chimney leaves its nest to find food for its offspring, it passes through a succession of places causally connected to one another until it returns to its place of origin ‘here’; and so on. Therefore, by grasping that objects obey certain physical principles and move in space independently of one another, we can come to assign causal significance to the interconnectedness of space in a non-causally indexical manner. In other words, the way things are at one place causally depends on the way they were at another place because of the possibility of objects moving in an independent manner from one place to the other. This proposal, by loosening the ties between our ‘objective’ conception of space and our practical || 17 These principles and their role in object representation will be explored in more detail in chapter seven.

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abilities as navigators, allows us to avoid the problems faced by the cognitive map strategy, while still making room for the idea that the space in which objects move is the same space in which we move. After all, part of what it is to understand the principle of independent movement is to understand that an object x moves independently not only from other objects around it but also from us (I will come back to this in chapter seven). But if this is what an objective conception of space is like, this is bad news for the conceptualist proposal. For according to the conceptualist our capacity to perceive objects in space must be supplemented by background conceptual capacities in order to yield singular demonstrative contents – more specifically, with a capacity to represent space in a so-called ‘objective’ manner. But notice that according to the present proposal of what an objective conception of space amounts to, the order of explanation is effectively reversed. Rather than thought about objects being supported by an objective conception of space, the reverse happens: we first come to understand that objects are unique, persistent entities which are internally causally connected and which move through space in an independent manner. Then, on this basis, we build our ‘objective’ conception of the spatial world, where the possibility of movement by objects from one place to another supports our grasp of the causal interconnectedness of space in a non-causally indexical manner. After all, for this notion of a so-called ‘objective’ conception of space to get a grip, it must already presuppose a conception of material objects as entities that persist in space and time independently of our perceptual encounters with them. If we were unable to understand that the object now at p is the same object which was then at p’, we would not understand that the way things are at p are causally dependent on the way things were at p’.18 Therefore, the conceptualist’s suggestion cannot be entirely right. It cannot be that our conception of objects as persisting entities requires a prior ‘objective’ conception of space. The order of explanation is reversed. This leaves us with a problem: if Campbell’s proposal successfully elucidates what it is to assign causal significance to the interconnectedness of space in a non-causally indexical manner, this presupposes a conception of objects as persisting entities, thus leaving our initial questions unanswered: what is it to understand that objects persist in space and time independently of our perceptual encounters with them? Another suggestion put forward by Campbell is that we can understand objects’ persistence in space and time by grasping their

|| 18 See Campbell 1993: 89.

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internal causal connectedness: that the current state of an object is causally dependent on its prior states (Campbell 1993: 89). But how exactly do we grasp the internal causal connectedness of an object? Here’s Campbell: Consider a cat chasing a mouse, for example, or watching a bird flap its wings and fly. It is unquestionable that the internal causal connectedness of the thing shows up in the cat’s representation of it – it is thinking of the thing as an object – but the internal causal connectedness shows up in the way in which the cat itself interacts with the thing, in perception of it or in acting upon it. (Campbell 1993: 92

But the problem with this proposal is that, as the passage above makes clear, this is only a practical understanding of internal causal connectedness. It is given to the cat only as a way of acting upon objects, exhausted in the cat’s expectations and anticipations concerning the object’s behaviour as their mutual interaction unfolds in time. But we have already seen (5.5) that a practical understanding of what objects are and how they behave is unable to distinguish between individuals and instances of property-kinds as the representata of one’s attention-based mental activities. The cat’s understanding of persistence and internal causal connectedness remains at the causally indexical level, and is thus unable to give us the stronger sense of persistence we were looking for, which extrapolates to non-perceptual contexts. But now we seem to have exhausted our options. On the one hand, we have encountered serious difficulties with the idea of elucidating our grasp of objects as persistent entities through an ‘objective’ conception of space, since the latter seems to build upon the former. But on the other hand, as soon we remove this ‘objective’ conception of space from our account of object representation, all that seems to be left is a practical understanding of what objects are and how they behave, as Campbell’s proposal makes clear. But although we may have managed to rule out one of the conceptualist’s positive proposals, we haven’t yet answered her challenge in a satisfactory manner. How can we explain our capacity to apprehend our external environment as structured into individuals rather than instances of property-kinds? What is it for one to be “suitably sensitive” to objects as unique, persisting entities, if not to understand that these objects have unique places in a so-called ‘objective’ spatiotemporal framework? Of course, this is not to say that there could not be other ways to account for an ‘objective’ conception of space, which do not appeal to a prior conception of objects as persistent entities and that is not tied to our practical abilities as navigators. I do not mean to suggest that the conceptualist’s proposal could not, in principle, be made to work. But if one chooses to go down this path, one is like-

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ly to encounter severe difficulties. Elucidating the idea of an objective conception of space, as some of the observations in this chapter already made clear, is something notoriously difficult to do.19 So if we can account for our capacity for singular representation in a way that does not require us to make a decision on what an objective conception of space might be, that would be preferable. And this is exactly what I intend to do in advancing the ‘pragmatic view of demonstrative thought’ in the last two chapters of this book.20 The basic idea behind this view, as we shall see, is that a practical understanding of what objects are and how they behave is sufficient to differentiate between objects and instances of property-kinds as the representata of our mental states. But before such a view can be advanced, we first need to dispense with what I’ve called ‘the orthodox view’ of practical knowledge, which was temporarily accepted for dialectical purposes throughout this chapter. In the orthodox view, practical knowledge contrasts with conceptual knowledge in that the former is local, context-bound and non-portable, with a content given in causally indexical terms. But this dichotomy between practical and conceptual knowledge is too rough, acknowledging only a very limited and primitive role for practical knowledge to play in our cognitive life. In order to move beyond this dichotomy in the next chapter I will propose a novel theory of practical knowledge based on the notion of a ‘cognitive space’. In this conception, properties like portability and objectivity are not ascribed to practical or conceptual knowledge on an ‘all-or-nothing’ basis but comes in degrees, as our practical knowledge gradually develops beyond the level of causal indexicality. With this theory in hand, in chapter seven I will finally apply it to the particular case of object representation, yielding what I call ‘the pragmatic view of demonstrative thought’: a pragmatist approach to singular representation where the capacity to apprehend our external environment as structured into individuals comes in degrees, supported by a practical knowledge of what objects are and how they behave.

|| 19 See also Bermudez 2003 and the essays collected in the first part of Eilan et al. 1993 for further difficulties with this notion. 20 Although I will make some (tentative) suggestions of how a so-called ‘objective’ conception of space may arise in chapter six (section 6.3).

The Pragmatic View of Demonstrative Thought I : Practical Knowledge .

Introduction: conceptualism and the explanatory gap

After going through the conceptualist challenge in chapter five, the problem we’ve ended up with is this: ascriptions of singular content seek to capture certain psychological and epistemic capacities on the part of a subject, whereby she is able to apprehend her external environment as structured into individual objects. This means that she must be suitably sensitive to certain constitutive features of individual objects, which distinguish them from other similar candidates for the representata of her object-directed mental states like particular instances of property-kinds . More specifically, she must be suitably sensitive to the persistence of objects – to the fact that they are unique entities that persist in time in the strong sense required by the conceptualist, which extrapolates to non-perceptual contexts. The conceptualist then suggested that our understanding of the persistence of objects required us to have a so-called ‘objective’ conception of space; for it is only on the basis of this conception that we come to understand that objects which occupy numerically distinct places are also numerically distinct even if they are qualitatively identical , regardless of our capacity to simultaneously perceive both places at once. We then understand that an object once encountered may continue to exist unperceived at a numerically distinct place, and may be encountered again at successive times in different places if it is capable of movement . According to this proposal, our capacity for singular representation is tied very closely to our capacity to represent space in terms of a ‘cognitive map’ – an internal, mental analogue of a cartographic representation, where every place is represented as simultaneously connected to every other sensu O’Keefe & 0adel . I have called this ‘the cognitive map strategy’. There was, however, one fundamental problem with this proposal. As the cognitive map strategy was formulated, one’s understanding that places are connected to one another – what I have called, following Campbell , the ‘simultaneous interconnectedness of space’ – is manifested only as a capacity to get to different places from whatever place one happens to be located. In this sense, space is given to a subject only as a way of navigating from one place to another, by different routes and shortcuts. But this leaves unclear why we should call this an ‘objective’ conception of space at all. In Campbell’s terminology, the contents of one’s conception of space remain at the causally indexi-

Introduction: conceptualism and the explanatory gap 

cal level, involving an implicit reference to one’s causal powers and practical abilities as a navigator. A more promising proposal, developed by Campbell , attempted to untie the strong links established by the cognitive map strategy between navigational abilities and an ‘objective’ conception of space. Campbell’s idea is that we could come to grasp the simultaneous interconnectedness of space in a noncausally indexical manner on the basis of the possibility of movement by other objects in space. By understanding that objects move independently from one another and from us across different places, we come to appreciate the simultaneous causal interconnectedness of space: the idea that the way things are at one place causally depends on the way they were at another place. This conception of space, based on the possibility of movement by other objects, is independent of whether we ourselves happen to be in one of these places, as well as of our own practical abilities as navigators. But the problem now is that this conception of the simultaneous causal interconnectedness of space already presupposes an understanding of objects as unique, persisting entities. After all, if an object moving from p to p’ is supposed to provide us with the idea that the way things are at p’ causally depends on the way they were at p, we need to understand that it is the very same object that was at p and is now at p’ – even if we are unable to perceptually track its movements from p to p’. Campbell’s proposal, in effect, reverses the order of explanation: we first come to conceive of objects as unique, persisting entities that are capable of movement across different places in an independent manner. And then, on this basis, we build our conception of an ‘objective’ spatial world, where every place is causally connected to every other. But if this is true, then we can no longer explain our sensitivity to the persistence of objects through the idea of an ‘objective’ conception of space. The order of explanation is reversed. How, then, can we explain what it is for a subject to be suitably sensitive to objects as unique, persisting entities? Campbell’s proposal appeals to our understanding of objects as ‘internally causally connected’, or the idea that the current condition of an object causally depends on its prior conditions. In this manner, we could come to understand that the state of the object at place p’ causally depends on its prior state at p and that its future state at p’’ will causally depend on its state at p’, and so on . But the problem is that, as Campbell explained it, this understanding of internal causal connectedness is of a practical nature: it’s something that shows up in the way we interact with the object, as we perceptually track it as a unity through time and motion, or learn to anticipate where it will be in the next moment on the basis of its prior position and

  The Pragmatic View of Demonstrative Thought I : Practical Knowledge direction of movement. In this sense, internal causal connectedness is given to us only as a way of interacting with objects, and cannot be used to explain the stronger sense of persistence emphasized in the conceptualist challenge. Our conception of persistence in terms of internal causal connectedness remains at the causally indexical level. But now we are left with an explanatory gap. Our goal is to explain what it is for one to be suitably sensitive to the persistence of objects in the strong sense required by the conceptualist, which extrapolates to non-perceptual contexts. But all we’ve been given so far is a practical understanding of internal causal connectedness, manifested in one’s on-going perceptual interactions with objects in the world. This kind of understanding, according to the orthodox view . , is local, non-portable and context-bound, with a content given in causally indexical terms. It cannot, therefore, serve as basis for the conception of persistence that’s needed here, which requires us to understand that the predicate ‘… persists in time’ applies to objects across perceptual and non-perceptual contexts. How can we bridge this explanatory gap? How can we, having as starting point a practical understanding of what objects are and how they behave, arrive at a conception of objects as unique, persisting entities, that trace their own spatiotemporal histories in the world across a series of unperceived places? The main difficulty here is that given the nature of practical knowledge put forward by the orthodox view, it is difficult to see how an explanation of singular representation in terms of practical knowledge could ever be given. On the contrary, it seems that a practical sensitivity to what objects are and how they behave can only yield knowledge that is local, context-bound and non-portable. But if a strong sense of persistence is needed in order to distinguish individual objects from instances of property-kinds, then without conceptual knowledge of objects this explanatory gap can never be bridged. Once the conceptualist challenge has been accepted – and chapter five gave us good reasons to do so – it seems that we are forced to answer it in the conceptualist’s own terms. At first sight, the pragmatic view has no hopes of getting off the ground. The goal of the next two chapters will be to argue that this is a mistake. The explanatory gap arises only because of a mistaken conception of practical knowledge suggested by the orthodox view, which confines it to the level of causal indexicality and acknowledges only a very limited and primitive role for it to play in our cognitive lives. This view severely restricts the theoretical role of practical knowledge in a theory of cognition, imposing a sharp dichotomy between practical and conceptual knowledge that is likely to do more harm than good.

Introduction: conceptualism and the explanatory gap 

)rom the characterization of practical knowledge given in the orthodox view, it is fit to capture only the kind of sensorimotor knowledge we exploit in successfully navigating our external environment and perceptually engaging with objects, and little else. )rom this perspective the world is given to us only in terms of subject-relative affordances, as a way of interacting with objects given our immediate needs and interests, something that cannot be transposed to other subjects or to other contexts. Our conception of the world is tied to our experiential awareness of it, dependent on our causal powers and contingent location in space and time. Only conceptual knowledge will allow us to see the world from a more disengaged point of view, detached from our particular perspective and immediate practical concerns. By deploying conceptual abilities in the way we experience the world, we turn the world into some kind of ‘object’, which can be experienced from different perspectives and by different subjects as the same world. Conceptual knowledge is what allows us to effect the necessary metaphysical separation between the subject of knowledge and the object of knowledge, allowing us to represent a certain subject matter in a way that is no longer bound to our contingent causal powers and experiential awareness of it. But once we put things this way, we are naturally led to conceptualist theories of demonstrative thought, which make a sharp distinction between perceptual and conceptual abilities in their explanation of singular representation. Even if conceptualist theories agree that an explanation of demonstrative thought must begin in perception, the insufficiency of perceptual or practical abilities in providing us with a conception of objects as unique, persisting entities leads the conceptualist to appeal to a supplementary level of conceptual knowledge, which is different in kind from practical knowledge. Due to their appeal to two distinct types of knowledge, we may call these theories, following Hatfield, ‘two-factor theories’ of singular representation. We have already discussed Hatfield’s two-factor theory in chapter five, but another good example of a conceptualist theory of this sort is Evans’ . The theory begins by characterizing a more primitive level of perception, specified in terms of informational states with non-conceptual content: a subject establishes an information-link with an object on the basis of an attentional act, which provides her with non-conceptual information about the states and doings of the object over time. The deliverances of the information-link provide the subject with her controlling conception of the object, which means that the

 See Hatfield

:

fn.

 The Pragmatic View of Demonstrative Thought I : Practical Knowledge

thoughts she entertains about the object, and the judgments she is disposed to make about it that it has a certain colour, a certain shape, that it is moving or stationary, etc. are a causal consequence of the subject’s acquisition of information, through the information-link, about the object’s colour/shape/ movement/etc. Evans : - . This controlling conception is dynamic, and evolves according to changes in the states and doings of the object detected through the information link : . Evans, however, famously rejected the idea that the mere existence of an information-link would be enough for one to be able to represent individual objects. )or singular representation to be possible, certain epistemic and psychological capacities are required. Evans’ idea – which I have briefly explored in chapter four – is that in addition to the information-link the subject should also have a practical ability to locate the object in egocentric space Evans : . What this means, according to the interpretation proposed in chapter four, is that the object acquires ‘spatial significance’ for the subject: the location where the object is perceived to be is the location the subject is disposed to orient herself towards in order to act upon the object. So far, this is fully compatible with the perceptualist theory of demonstrative thought sketched in chapter four. Evans, however, makes the further requirement that the subject’s practical ability to locate the object in space be supplemented by ‘conceptual’ abilities – more specifically, the ability to represent space in an ‘objective’ manner, in terms of a cognitive map. To quote Evans: We are now in a position to answer the question what makes demonstrative identification of spatially located material objects possible. In the ordinary perceptual situation, not only will there be an information-link between subject and object, but also the subject will know, or will be able to discover, upon the basis of that link, where the object is. Given the subject’s general knowledge of what makes propositions of the form [ = p] true, for arbitrary , when p is an Idea of a position in his egocentric space [and  is a position in public, objective space], and given that he has located, or is able to locate, the object in his egocentric space, he can then be said to know what it is for [This = the object at  now] to be true for arbitrary  . Hence he can be said to have an adequate Idea of the object. Evans : -

This passage clearly illustrates Evans’ two-factor theory, which calls for two kinds of abilities in order for singular demonstrative representation to be possible. At the more primitive level, the subject establishes an information-link with

 See specially Evans

:

-

.

Introduction: conceptualism and the explanatory gap 

the object, and the object acquires spatial significance for her. Then, she must be able to go beyond her own perspectival mode of identification of the object and bring conceptual abilities to bear in perception, representing the spatial location where the object is perceived within a objective cognitive map of space. This is captured by what Evans calls the subject’s general knowledge of what makes propositions of the form [ = p] true : a conceptual ability to represent one’s egocentric space within a cognitive map. I have already raised some difficulties to this proposal in chapter five. But what is important to keep in mind here is that the supplementary, conceptual level of explanation is brought in precisely in order to bridge the explanatory gap previously alluded to. Evans noticed that if one is to think of a material object as such, i.e., as a unique, persisting entity, one should be able to attribute properties to the object that go beyond what can be immediately gathered on the basis of one’s perception of it Evans : . )or example, properties like ‘having been bought in )rance during world war II’, or ‘being on its way to Brazil on a cargo ship’ – which require one to understand that the perceived object has come into existence long before one’s perceptual encounter with it, and will continue to exist after the perceptual encounter comes to an end. We cannot explain this in terms of our practical ability to locate the object: this capacity only places objects in our egocentric space, and is constitutively dependent on the presence of an information-link and on our current dispositions and causal powers. 0o matter how much we enrich these dispositions and sensorimotor abilities, they will never have the explanatory power which is characteristic of conceptual abilities: to give us knowledge that is ‘portable’ and ‘objective’, taking us beyond the level of causal indexicality and providing us with a conception of objects as unique, persisting entities. This is exactly the kind of sharp dichotomy that I will attempt to dissolve. In order to do so, I will introduce, and defend, a theoretical framework for the study of demonstrative thought I shall call ‘the pragmatic view’. Its name derives from the fact that the cognitive abilities underlying our capacity to think of individual objects will be conceived in terms of ‘practical knowledge’, albeit in a very different sense from that put forward by the orthodox view. Although this knowledge surely has its origins in the organism’s active interactions with objects in its external environment, the theory of practical knowledge to be developed in this chapter allows us to follow it in a distinctive pattern of cognitive development, transposing the more primitive level of causal indexicality while still falling short of the more sophisticated abilities posited by the conceptualist. To be clear, I do not deny that the contrast between practical and conceptual knowledge put forward by the orthodox view has some intuitive appeal. This

 The Pragmatic View of Demonstrative Thought I : Practical Knowledge

contrast seems to capture an important pre-theoretical distinction between two different ways to cognitively engage with the world. To go back to Cussins’ example discussed in chapter five, my knowledge of ‘ km/h’ as a way of driving through the streets of a big city is indeed very different from my knowledge of ‘ km/h’ in units. It is perfectly possible for me to have a theoretical, detached understanding of a certain subject matter without having a practical, engaged one and vice-versa . This is exactly why reading an instruction manual on driving, no matter how detailed, will never make me a skilled driver without the appropriate practical training. I do not deny any of these plausible points. But I reject the idea that practical knowledge must be restricted to more primitive forms of sensorimotor knowledge in service of the organism’s immediate concerns, which stand in sharp contrast to reflective, disengaged theoretical knowledge. Practical knowledge of ‘ km/h’, I will argue section . , can become portable and be applied to other subjects in other circumstances even if not to the full range of circumstances that knowledge of ‘ km/h’ in units allows me to . In fact, I shall be arguing that so-called practical and conceptual abilities take place in a continuum: from primitive sensorimotor knowledge exhibiting properties like locality, non-portability and context-boundedness, to more sophisticated forms of understanding that go beyond the level of causal indexicality. Although there may be clear cases of so-called ‘conceptual’ abilities at one end of the cognitive spectrum, and so-called ‘practical’ abilities on the other, there need not be a precise point where practical abilities end and conceptual abilities begin. Rather, what we have are higher or lower degrees of objectivity and portability, which characterize our knowledge and understanding of the world on the basis of our psychological and epistemic capacities. This more comprehensive notion of practical knowledge will be put forward as a way of moving beyond two-factor theories. Rather than having to supplement practical knowledge with conceptual knowledge, the pragmatic view allows us to explain our capacity to represent individual objects in terms of a practical sensitivity to certain constitutive features of objects, which gradually acquires a higher degree of objectivity and portability. The resulting view will be a novel way of looking at demonstrative thought, which should be of interest to perceptualists and conceptualists alike. To the former, who maintain that singular representation must be explained at the level of preconceptual cognition, and to the latter, who feel that perceptual processes and mechanisms often give us too little in the way of the subject’s epistemic and psychological capacities. The pragmatic view shares both of these insights. It proposes a way to do justice to both, with a theoretical framework structured in terms of a practical

Introduction: conceptualism and the explanatory gap 



knowledge of objects, which develop along different dimensions so as to encompass an increasing number of circumstances and move beyond the level of causal indexicality. But here one may object: isn’t this a mere terminological dispute? That is to say, if we maintain that the kind of knowledge the conceptualist refers to as ‘conceptual’ may be captured by a more comprehensive notion of practical knowledge, then indeed we can dispense with a two-factor theory of singular representation. But insofar as the pragmatic view also grants that portable, objective knowledge of objects is required in order for singular representation to be possible, it is not clear that there will be any substantial difference between two-factor theories and the pragmatic view. The issue seems to be merely terminological, hanging on how we define knowledge that is ‘portable’ and ‘objective.’ This is not true. There are, I maintain, substantial differences between the two approaches. Two-factor theories make us look at perceptual and sensorimotor abilities as being radically opposed to reflective, theoretical abilities, as two fundamentally different ways of engaging with the world: each characterized in terms of different properties, with contents given in different terms. Part of my goal in defending the pragmatic view is precisely to show that these two ways of engaging with the world do not contrast with one another but take place in a single cognitive space, which we learn to expand as we develop our knowledge of the world along different dimensions. In other words, according to the pragmatic view whether one’s knowledge of a certain subject matter exhibits properties like portability and objectivity is not an all-or-nothing matter. Our knowledge of the empirical world acquires portability and objectivity in degrees, as it becomes increasingly less dependent on our own idiosyncratic perspective and causal powers. Two-factor views, by construing practical and conceptual knowledge as being fundamentally different in kind from one another, do not allow us to acknowledge this. As practical knowledge in two-factor theories is too primitive to account for our capacity for singular representation, the conceptualist is forced to bring in conceptual knowledge in order to bridge the explanatory gap, by which she usually means abilities at the higher end of the cognitive spectrum: those that exhibit a maximal degree of portability and objectivity, wholly independent of the subject’s dispositions and causal powers. As a consequence, we end up with a highly intellectualistic theory of demonstrative thought, according to which our capacity for singular representation is inextricably tied to our capacity to adopt a more reflective and detached stance towards the world. Singularity, in the conceptualist’s view, comes ‘from above’: we can only under-

 The Pragmatic View of Demonstrative Thought I : Practical Knowledge

stand that something is an individual object by placing it in an objective and disengaged picture of the world. The pragmatic view, in contrast, seeks to put our understanding of objects back where it belongs: in our situated practices and interactions with objects as embodied agents. Rather than appealing to an ‘objective’ picture of the empirical world in order to explain singular representation, the pragmatic view acknowledges that the capacity to apprehend our external environment as structured into individual objects is something that comes in degrees, as we gradually learn to extrapolate our sensorimotor knowledge acquired on the basis of our interactions with objects beyond our own perceptual situation. This is more than just a terminological point, and has a direct bearing on how we construe explanations of mental and cognitive phenomena. The pragmatic view will be developed in two stages: in this chapter I will show what is wrong with the orthodox view of practical knowledge, and why we should dismiss it. In its place, I will propose a novel way of looking at practical knowledge in terms of ‘cognitive spaces’, inspired by Adrian Cussins’ theory of cognitive trails . Once this theory of practical knowledge has been put into place, chapter seven will then be dedicated to the application of this theory to our object of study, namely, demonstrative thought – thus yielding what I have been calling ‘the pragmatic view’.

. Practical and image-like knowledge What is wrong with the contrast suggested by the orthodox view between practical and conceptual knowledge? We can start our discussion with an example of a common practical ability like bike riding. When we first learn how to ride a bike, it is natural to describe the knowledge we acquire as being practical in nature. We begin by learning how to adjust and orient our body appropriately as the activity unfolds in time, how to balance ourselves on top of the bike, how to coordinate our pedalling, how to adjust our grip on the handlebars, how far to turn the handlebar in order to make curves in a smooth and stable fashion, and so on. This kind of knowledge is sensorimotor in nature, and is constitutively connected to sensory input and motor output: we manifest our practical

 This is exactly Evans’ idea of the ‘)undamental Level of Thought’, which I have already explained in chapter five: the idea that we can only represent individual objects by identifying them in a ‘fundamental’ way’, which purports to be an objective form of identification see chapter five, section . .

Practical and image-like knowledge 

knowledge of bike riding by responding to changing circumstances road conditions, curves, obstacles etc. in the appropriate way with our bodies, as the activity unfolds in time. Knowing how to ride a bike in this manner does not require us to able to conceptualize this knowledge in any way. It is plausible to suppose that at this level, our knowledge of bike riding indeed exhibits the properties traditionally associated with practical knowledge: it is local, context-bound and non-portable. It is tied to our actual engagements with bike riding and manifested only in action. There is, at this level, no metaphysical separation between the rider as a subject of knowledge and the activity of bike riding as an object of knowledge. We cannot yet represent our knowledge independently of its manifestations in action. Its contents, correspondingly, are better described in causally indexical terms: they are dependent on our own dispositions and causal powers. But perhaps there will come a time when we become able to articulate the different ways in which we adjust our body posture, and the various movements we make with our legs and arms in order to keep ourselves steady on the bike under various conditions. At this point, we may say that we have acquired a more sophisticated understanding of bike riding – one that allows us to abstract away from our own experiential awareness of bike riding and transpose our knowledge to other subjects as well. We can, for example, write down a set of instructions specifying what one should do when riding a bike in various situations, which we can present to others in a way that will allow them to appreciate the skill of bike riding from different perspectives. We have here adopted a more disengaged and reflective perspective on bike riding, which is no longer dependent on our actually riding one. According to the orthodox view, we have acquired a conceptual understanding of bike riding: one that is portable and objective, with a content specified in non-causally indexical terms. There is no reference to any particular person’s dispositions or causal powers. I do not doubt that we can approach the activity of bike riding from these two different perspectives, and that our knowledge of bike riding in each case will have different properties. But I doubt that this contrast, as formulated, is fine-grained enough to capture all the different ways in which we may manifest our knowledge of bike riding. Jung and 0ewen , for example, have argued that we should acknowledge a third form of knowledge, which does not fit neatly into the practical/conceptual dichotomy suggested by the orthodox view. They call this ‘image-like knowledge’, which, as its name indicates, is based on psychological abilities like imagination, motor and visual imagery, iconic memories etc. As the authors put it,

 The Pragmatic View of Demonstrative Thought I : Practical Knowledge

This knowledge is partially independent from external sensory stimuli because imagination is possible without a typical external source. )urthermore, that knowledge is very rich and fine-grained in structure such that it usually contains more information than can be made explicit by the conceptual or propositional representations available for a ‘normal’ person who is not an expert in all areas . Therefore image-like knowledge formats differ from sensorimotor representations, because they can be activated independently from performing or observing an action and they differ from propositional representations since they are in principle only partially explicable by propositions, i.e. by concepts and their combinations. Jung & 0ewen :

We exercise image-like knowledge of bike riding when we bring to mind a past bike race as we lie in bed to sleep, and see ourselves with our mind’s eye pedalling hard in those last few hundred meters before the finish line; or when we imagine a biking activity in our minds performed by other subjects; and so on. One striking feature of image-like knowledge is that it already involves some degree of objectification of the activity in question, beyond the level of causal indexicality: mental images of bike riding allow us to represent this activity independently of our actually engaging in it. Having an image-like knowledge of bike riding affords just enough metaphysical separation between the subject of knowledge and the object of knowledge so as to allow us to apply it to other subjects as well: we can imagine other persons riding a bike in the same way as we would. We become able to represent our ability in a more general way, which is no longer tied to our dispositions and causal powers, as an ability that is also performable by others Jung & 0ewen : . But although there is already some level of objectification and portability in image-like knowledge, this form of knowledge is not easily assimilated into conceptual knowledge. )or even if we are able to form mental images and perform motor simulations whose contents will be specified in non-causally indexical terms, we may be unable to linguistically articulate these movements as a set of instructions or conceptualize them in any way. The content of these memories and imaginings, as Jung and 0ewen put it, is nonconceptual, subserved by iconic non-symbolic representations. This gives us good reason to acknowledge, with Jung and 0ewen, a third form of knowledge which is different in kind from both practical and conceptual knowledge. This knowledge is to some extent portable and objective, but not yet conceptualized.  Jung and 0ewen suggest that these iconic representations should be identified with what Paivio has called ‘analogue codes’, which represent external stimuli in a way that retains the perceptual features of what is being observed. These details, however, are not important for present purposes see Jung & 0ewen : .

Practical and image-like knowledge 

Jung and 0ewen are certainly right to point out that there are other ways for our knowledge to be to a certain extent portable and objective, other than through conceptualization and linguistic articulation. Image-like knowledge is a perfect example of knowledge that takes us beyond the level of causal indexicality without being linguistically articulated or conceptualized. But rather than taking this to be yet a further type of knowledge, different in kind from both practical and conceptual knowledge, I propose to interpret Jung and 0ewen’s observations in a different way. In the pragmatic view, cognitive abilities like motor and visual imagery, iconic memory, imagination etc., do not constitute a set of abilities that distinguish one form of knowledge from others, but are different means through which our practical knowledge may acquire a higher degree of portability and objectivity. Each of these abilities may be manifested by a subject in various degrees and in different ways i.e., in one kind of task but not in another , in a more-or-less independent manner. In other words, what Jung and 0ewen call ‘image-like knowledge’ is also something that comes in degrees, and is inextricably tied up with what they call ‘practical knowledge’. To illustrate with an example, let’s suppose that after some practice with bike riding I am now in a position to simulate, in non-riding circumstances, the bodily movements I normally make when I am riding a bike. If you ask me what I do with my body when I am riding a bike, I can position myself in a certain way and execute a series of synchronous movements with my arms and legs. This is not a case of mere imitation: I am not simply mimicking a set of movements I may have seen elsewhere. On the contrary, I simulate these movements intelligently and purposefully as my bike riding movements. 0evertheless, I may still be unable to form a mental image of these movements, or use this knowledge in order to understand what it is for others to engage in bike riding. I have to actually perform these movements myself in order to represent them. In this case, although my capacity to manifest my knowledge is no longer dependent on my having actual perceptual input, it is still dependent on my own bodily movements. What should we say about this? When I simulate my bodily movements in this manner, am I exercising practical or image-like knowledge? It certainly involves skills of motor imagery and simulation, but not in a way that is easily applied to others as image-like knowledge is supposed to be. Although this allows me to extrapolate some of my sensorimotor knowledge to some situations beyond actual riding situations, this knowledge is still dependent on my actually moving my body in a certain way. I wouldn’t know how to apply it in situations where I am not myself moving although I can apply it to situations

  The Pragmatic View of Demonstrative Thought I : Practical Knowledge where I am not myself riding . If you asked me, for example, is this how bike riding is done? while moving your body in a certain way, I would be unable to give you a positive or negative answer. I could offer you a bodily movement in response, but I would not know whether my way of moving matches yours or not. I would be unable to correct you or give you any advice, except by moving and hoping that you will be able to assimilate my bodily movements into your practical knowledge of bike riding. So what should our final verdict be? Is this ‘practical’ or ‘image-like’ knowledge? It cannot be wholly practical, since it is transposable to other nonriding circumstances; there is just enough metaphysical separation between the subject of knowledge and the object of knowledge for me to represent my actions in non-riding circumstances, where I am not receiving actual perceptual input from the activity in question. This goes against the definition of practical knowledge, which is supposed to be local, non-portable and context-bound. But at the same time, it also seems too primitive to be called ‘image-like’ knowledge. There is some rudimentary form of motor imagery at play, but not in a format that is easily applied to others, as image-like knowledge is supposed to be. It is still dependent on my actually moving my body in certain ways. What should we say about this? The pragmatic view says we don’t need to make a decision one way or another. Abilities of motor imagery and simulation mark the beginnings of objectification and portability, but the point here is that these properties come in degrees. What we learn in practicing a certain skill is among other things how to transpose what we have learned in one situation to other situations, so as to be able to represent this skilful activity as the same activity from different perspectives and in different circumstances. At first, we might be able to transpose only some of the micro-adjustments we make to a very narrow range of situations, and in a very limited way. As the example above illustrates, we might learn how to emulate with our bodies, in non-riding circumstances, the movements and bodily adjustments we normally make when we are riding a bike. As our learning continues to progress, we may also learn how to form mental images of bike riding, recall our prior riding experiences in an iconic format, draw the sequence of bodily movements we normally make on a piece of paper, linguistically articulate it, and so on. When we acquire these more sophisticated capacities, our knowledge of bike riding – which was initially purely sensorimotor – is greatly expanded. But there need not be a precise point where we acquire ‘image-like’ or ‘conceptual’ knowledge of bike riding. It’s much more plausible to suppose that psychological abilities that are typically associated with image-like or conceptual

Practical and image-like knowledge 

knowledge come in degrees, as we slowly learn how to transpose our knowledge to other circumstances and other riders through different means. To anticipate a bit of what will follow, my suggestion is that we drop this threefold distinction between different types of knowledge and characterize this whole spectrum of abilities as demarcating a zone of competence within the ‘cognitive space’ of bike riding this will be made more clear in section . . At first, our zone of competence within this space is very restricted, limited to circumstances in which we are actually engaged in bike riding. In this case, we shall say that our practical knowledge of bike riding is local, non-portable and context-bound. But as we develop our ability and learn to extrapolate our knowledge to other circumstances, our zone of competence within this cognitive space is greatly expanded. We have acquired more ways of moving through it, more circumstances in which we can represent bike riding as the same activity which is performable by others as well. As our zone of competence within this cognitive space is expanded, our practical knowledge is endowed with a higher degree of portability and objectivity. To connect this point with our previous discussion, one way to achieve a higher degree of portability and objectivity is through abilities that are typically associated with image-like knowledge: visual and motor imagery, iconic memory, imagination, etc. Another way is through abilities that are typically associated with conceptual knowledge: linguistic abilities, abstract reasoning, etc. But what matters in the pragmatic view is not so much whether one’s knowledge is practical non-portable and nonconceptual , image-like portable and nonconceptual or conceptual portable and conceptual : rather, we ask for the degree in which one’s knowledge is portable and objective, depending on what kind of abilities one can bring to bear in one’s embodied activity. This idea – that practical abilities come in degrees – also points to another important aspect of the pragmatic view. While there may be clear cases of not knowing how to ride a bike and clear cases of knowing how to ride one, there need not be a precise point in the development of bike riding where we decide that one has acquired knowledge of how to ride a bike. )or which point would that be? If I can stay on top of a bike for ten minutes without the supplementary back wheels, do I thereby have the ability to ride a bike? What if I can ride it on flat terrain, but not up or downhill? Or if I can go in a straight line until exhaustion, but cannot make curves or brake without falling off? And if I can do all these things in dry conditions, but not in wet or muddy terrain? Do I then have the ability to ride a bike? This problem is, of course, spurious. If we acknowledge that practical abilities come in degrees we don’t need to answer these questions, as we do not need

 The Pragmatic View of Demonstrative Thought I : Practical Knowledge

to pick an arbitrary point where skilful riding begins. As Millikan says in an anecdotal story, when a child on her way to violin classes was asked if she was learning how to play the violin, she replied: I already know how to play the violin. I am learning how to do it better” Millikan : . This is important, and confers distinctive advantages on the pragmatic view. )or if we explain demonstrative thought in terms of practical abilities, we can now say that the ability to apprehend one’s external environment as structured into individuals is something that also comes in degrees. In other words, one being suitably sensitive to certain constitutive features of objects need not be an all-or-nothing matter. One can be sensitive to some properties, in some circumstances, from certain perspectives, while failing to recognize these same properties in other circumstances from different perspectives. As these abilities develop we become increasingly better at recognizing these properties in a wider range of circumstances and from different perspectives, but there need not be a point where one suddenly becomes suitably sensitive to what objects are and how they behave. This is a practical ability, which comes in degrees. At first, our understanding of a property like persistence may indeed be non-portable and context-bound, but as it develops we become able to transpose features of our own experience of objects in order to recognize that the predicate ‘…persists in time’ may apply to an object even in non-perceptual contexts. This provides us with a very different framework for the study of demonstrative thought, where the capacity to represent individual objects is conceived as a practical ability, which comes in degrees and cuts across the perceptualist/conceptualist controversy.

.

Practical knowledge and space

One interesting consequence of this more comprehensive notion of practical abilities is that it allows us to clarify a problematic point raised in chapter five, concerning the idea of a so-called ‘objective’ conception of space and cognitive maps. In that chapter, I have raised serious difficulties to the conceptualist’s attempts to explain our objective conception of space in terms of our capacity to form cognitive maps; but there was never any doubt that we do have, and that we often employ, more sophisticated forms of spatial representations like this. As Robin Le Poidevin puts it, …we may cite as evidence for an objective cognitive map the fact that we engage in reciprocal communication with subjects who have different spatial perspectives and so do not share our egocentric space. We might, for example, be giving instructions to someone

Practical knowledge and space 

moving about on the sea-bed, or in space, on the basis of what we can observe of him and his environment on a screen. Here we need to reconcile different egocentric representations, and since we cannot simultaneously entertain two such conflicting representations, the best explanation of our ability to communicate with others in these situations is that we map their positions onto an objective space. Le Poidevin : -

In this case, it is clear that we employ a more sophisticated form of spatial knowledge, organized in terms of ‘configurational’ knowledge of space. ‘Configurational knowledge’ is the kind of spatial knowledge we acquire from cartographic maps and other so-called ‘objective’ spatial representations, such as an anatomical drawing of the human body or a model of the solar system. This allows us to grasp the spatial relations between any two arbitrary represented points independently of our perspective upon the represented spatial configuration Le Poidevin : . To illustrate with an example, if we have a map of Paris in our hands and need to guide a tourist from the Place Saint Michel to the Notre Dame, we can use the spatial configuration represented in the map in order to give the appropriate directions. We don’t need to occupy one of the places represented in the map, or be able to navigate through the 1er arrondissement of Paris ourselves: we can guide the tourist by reading the map and grasping the spatial relations between different points, which does not depend in any way on our contingent position in space. But of course, a Parisian who is sufficiently familiar with the 1er arrondissement can probably guide the tourist even in the absence of an actual physical map. She might do that on the basis of her configurational knowledge of the 1er arrondissement, her own mental model of this space where the streets and the relevant landmarks are represented as in a cartographic map: as simultaneously related to one another independently of the contingent position she happens to occupy in that space. But even if it is uncontroversial that we are normally able to form such models, when do we move from simple route knowledge to this more complex form of configurational knowledge? Is it only when we are able to guide someone through a certain spatial configuration, regardless of our own position in it? This cannot be right. I may, for example, be perfectly able to construe a maplike model of a spatial configuration x, manifested in my ability to draw a map of x where the spatial relations between different points are adequately represented. But at the same time, I may be unable to give spoken instructions to  ‘Configurational knowledge’ of space stands in contrast with simpler ‘route knowledge’, which supposedly exploit different forms of spatial representation as explained in chapter five, section . .

 The Pragmatic View of Demonstrative Thought I : Practical Knowledge

another subject who wishes to navigate through x. I may, for example, constantly mix my ‘lefts’ and ‘rights’, or be unable to coordinate the subject’s perspective upon x within my own mental model of it. So although the ability to give spatial directions to others with a different perspective would be sufficient to attribute one with a configurational knowledge of space, it is not necessary: this knowledge may be manifested in other ways. We can make this point clearer with an empirical study conducted by Pick and Lockman , who wished, precisely, to test children’s configurational knowledge of space. Pick and Lockman tested two groups of children, from three to four years old and from eight to ten, in their own multi-dwelling house. The children were individually taken to an arbitrary point in the house and asked to point directly to a certain piece of furniture in another room, or to the direction where another room was located, when these were currently hidden from view behind walls or through floors. What they found is that younger children were quite bad in the pointing task, while older children showed remarkable accuracy see Pick for review and discussion . One way to explain this discrepancy is by attributing to the older children a configurational knowledge of space, which the younger children lack. Although three to four year olds can unproblematically get to different rooms from whatever place they happen to be located in the house, their navigational abilities seem to follow a fixed ‘route’ knowledge, which cannot be abstracted away from their own contingent position in the house and the landmarks they use in order to learn these routes. Older children, in contrast, are able to form a mental model of the house they live in where the spatial relations between different rooms are simultaneously represented, and exploit this configurational knowledge in order to perform successfully in the pointing task. Things, however, are not so simple. When Pick and Lockman modified the task instructions slightly, the younger children also showed signs of configurational knowledge. If instead of asking them to point to the direction of certain places they asked questions like ‘if you were looking out of the bathroom window right now, what would you see?’, or ‘is mommy’s room in the front or the back of the house?’, the younger children would give accurate answers Pick : - . This suggests that three to four year olds may already be able to form a mental model of their house through visual imagery, although their capacity to coordinate this mental model with their own egocentric position in the house is still poor. They seem able to grasp the spatial relations between rooms by taking a different perspective on the model in their mind’s eye, so to speak, but they seem unable use this model in order to perform successfully in the pointing task.

Practical knowledge and space 



Based on these observations, should we credit these children with configurational knowledge of space? Or are they simply bringing to mind iconic representations of routes they have previously learned? It’s not clear how to give an answer in one way or another. The problem, as Pick notices, is where to draw the line or how to define when the process of localizing out-of-sight objects is accomplished with perceptual updating and when it is accomplished on the basis of configurational knowledge Pick : . Perhaps younger children are already able to form a mental model of space, although their capacity to use the model is still very limited and task-specific. Or perhaps they are only able to visualize routes they have previously learned, and answer questions about what they would find along these routes on the basis of iconic memory. How can we settle for one kind of explanation over another? We don’t have to. The capacity to represent space in a map-like fashion does not need to be an all-or-nothing matter, but may come in degrees. In other words, there need not be a precise point when we move from route to configurational knowledge. Instead, we should distinguish a whole array of skills we gradually learn to integrate and bring to bear in our spatial behaviour, which jointly contribute to give us a more stable and reliable picture of the spatial world. Among these we could cite, for example: . 0avigate efficiently towards a goal . Point to the direction of unseen locations . Take novel shortcuts . Imagine what the place we currently occupy would look like from a different perspective . Draw a map . Give verbal instructions to others . Use others’ verbal instructions in navigation This list is, of course, by no means exhaustive, and each kind of ability may be manifested in different ways and in different circumstances. As one learns how to apply these skills in a more efficient manner in a wider range of circumstances, one gradually builds a more objective picture of the spatial world, which is increasingly less dependent on one’s contingent position in space and time. But there need not be a precise point where one’s understanding of space ceases to be ‘practical’ and becomes ‘conceptual’. Rather, there are just higher or lower degrees of portability and objectivity. The capacity of three and four year olds to visualize their house from different perspectives already shows some degree of portability and objectivity, although at this point of cognitive development their spatial abilities are still limited and task-specific.

 The Pragmatic View of Demonstrative Thought I : Practical Knowledge

To connect this point with our earlier discussion of cognitive maps, these observations suggest that Gallistel’s notion of cognitive maps, which makes no sharp distinction between route and configurational knowledge, is more compatible with the pragmatic view. In Gallistel’s notion there is no difference in kind between simpler and more complex forms of spatial representation, other than a difference in the amount of information encoded: what O’Keefe & 0adel call a ‘cognitive map’ is something that comes in degrees in Gallistel’s view. A full treatment of this issue, however, would require further discussion, which is beyond the scope of this book. In any case, as this issue is still controversial, we don’t have to make a decision one way or another at this point: the pragmatic view of spatial representation can be put forward independently of whether it is supported by Gallistel’s notion of cognitive map representations. To conclude, the contrast between practical and conceptual knowledge put forward by the orthodox view is starting to look less appealing. Although it may be true that at the beginning of one’s cognitive development one’s knowledge of a certain subject matter p will be best characterized in terms of properties like locality, non-portability and context-boundedness, and have its contents specified in causally indexical terms, it would be wrong to restrict practical knowledge in this manner. The pragmatic view acknowledges that practical abilities may develop beyond the level of causal indexicality, as one gradually learns to transpose one’s own perspective and becomes able to apply one’s practical knowledge in other circumstances. And once we acknowledge this fact, we shall finally be in a position to bridge the explanatory gap: we no longer need to appeal to conceptual knowledge in order to explain what it is for one to be suitably sensitive to what objects are and how they behave. The path will then be open to a novel theory of demonstrative thought, structured in terms of practical knowledge. Much of this chapter will be dedicated to spelling out what I take practical knowledge to be, and how it can develop beyond the level of causal indexicality.

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The historical-dispositional account and its limits

A theory of practical knowledge could not begin without an account of practical abilities. After all, both notions are closely connected: if I have a practical abil But see Bennett , Klatzky , Mc0amara & Shelton , Bermudez and the essays collected in the first part of Eilan et al. for informative and critical discussions of cognitive maps.

The historical-dispositional account and its limits 

ity to ride a bike, for example, I also have a practical knowledge of bike riding. Conversely, if I have a practical knowledge of bike riding, I should also have among other things a practical ability to ride a bike. But my practical knowledge of bike riding may outstrip my practical ability to ride a bike in various ways. It can also subsume a range of different cognitive abilities, besides sensorimotor skills deployed in bike riding: for example, visual and motor imagery, imagination, etc. This is why it would be more precise to say that my practical knowledge of bike riding can be applied to different subjects in other circumstances, not that my practical ability to ride a bike can. I use my practical knowledge of bike riding in order to understand what it is for others to have the same ability as I do. But what exactly is a practical ability to engage in a certain activity A, and how does it relate to practical knowledge of A? The orthodox definition gave us very clear criteria for understanding practical abilities and practical knowledge: practical knowledge is knowledge of a certain subject matter p that is local, nonportable and context-bound, with a content specified in causally indexical terms. Accordingly, practical knowledge presents us with a world only as a way of acting and navigating through it. There’s no metaphysical separation between the subject of knowledge and the object of knowledge, which would be necessary for one to be able to represent the world as the same world from different perspectives and in other circumstances. As we’ve also seen in the last section, Jung and 0ewen’s account basically agrees with this picture. Although they rightfully identify further ways in which our knowledge could become portable without being conceptually or linguistically articulated, they still reserve the term ‘practical knowledge’ for more primitive sensorimotor skills, subserved by nonconceptual sensorimotor representations. As in the orthodox view, practical knowledge is still restricted to the level of causal indexicality. I have already expressed some reservations concerning the orthodox view, but it is undeniable that there’s some intuitive appeal to it. Cussins’ example involving two ways of knowing about speed – which lies at the basis of the orthodox view – is intuitively compelling precisely because it captures an important pre-theoretical distinction between two different ways in which we can cognitively engage with the world. So if we want to move beyond this simple dichotomy and propose a novel way of looking at practical abilities and practical knowledge, we must be more precise about what practical abilities and practical knowledge are, and in which way the present account differs from the orthodox view.

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 The Pragmatic View of Demonstrative Thought I : Practical Knowledge

The most straightforward way to understand practical abilities is in terms of simple dispositions: to have an ability to do A, one might say, is just to have a disposition to do A successfully. We may call this the ‘dispositional account’ of practical abilities. If I have the ability to ride a bike, for example, then I should be disposed to ride a bike successfully. If I do not have these dispositions, then I do not have the ability to ride a bike. This simple dispositional account, however, does not take us very far. As Millikan notices, I have dispositions to do certain things in certain circumstances that do not correspond to abilities of mine. )or example, I have dispositions to leave footsteps in the snow, to attract nearby fleas, or to leave sweat marks on my shirt when I go jogging, but these are hardly abilities of mines, in the relevant sense that is connected to practical knowledge Millikan : . What is missing here is some reference to the organism’s learning of the activity in question. Leaving footsteps in the snow and attracting fleas are not things I have learned, abilities I have acquired through practice. This is also why we don’t say that the ability of human beings to see in colour , for example, is a real ability in the relevant sense, connected to practical knowledge – it is not something we have acquired on the basis of practice and learning. Even if we have dispositions to do these things in certain circumstances, the lack of learning and practice on our part suffices to dismiss these cases from our account of practical abilities and practical knowledge. A more promising suggestion, put forward by Jung and 0ewen, is this: a practical ability to do A is a disposition to do A successfully acquired through practice and learning Jung & 0ewen : . In this picture, we explain my ability to ride a bike in terms of my having acquired, through practice and learning, dispositions to ride bikes successfully. If I have no dispositions whatsoever to do so, or if these dispositions were not acquired through practice and learning, then I do not have the ability to ride a bike. The appeal to learning and practice takes us a step beyond the simple account, and allows us to exclude the more problematic cases mentioned above. Moreover, it also deals efficiently with cases of ‘beginner’s luck’, whereby one succeeds in a task by pure chance, without having learned the relevant ability. )or example, I never engaged in archery before, but if I happen to pick up a bow for the first time, shoot an arrow and score a bull’s eye, I do not thereby have the corresponding practical ability. I may be a very lucky person, but I am far from being a skilled archer Jung and 0ewen : , 0oë : . But although this account is on the right track, it cannot be right as it stands. )or starters, even if I have the ability to do A, it is not the case that I will be disposed to perform A successfully in any kind of circumstance. If I have the

The historical-dispositional account and its limits 

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ability to ride a bike, for example, I may be disposed to ride bikes successfully when I am in the presence of a functioning bike in a suitable terrain, if I were to try to do so in these circumstances. I do not have dispositions to ride a bike successfully while I am swimming in the ocean or flying on an airplane. In other words, my dispositions to ride a bike are successfully manifested only in the appropriate bike-riding circumstances, which must be specified in our definition of practical abilities. To be more precise, we should qualify the dispositional account in the following way: The dispositional account: S has a practical ability to do A = S has a disposition to do A successfully, acquired through practice and learning, if S were to try to do so in A-appropriate circumstances.

This more complex version of the dispositional account seems to yield the right results: if I find myself in one of these circumstances, and if I were to try to A, I should have a disposition to do so successfully. Otherwise, I would not be credited with the ability to do A. Moreover, this account is also able to deal with a common objection raised against dispositional accounts of practical abilities. In an example adapted from Stanley and Williamson , imagine that an experienced bike rider loses both of her legs in a tragic accident. In this case, even if she were placed in the appropriate bike-riding circumstances, she wouldn’t have dispositions to ride a bike successfully. According to the dispositional account this would mean she no longer has the relevant ability, but this seems wrong: it would be strange to suppose that the ability would suddenly disappear just as soon as the amputation takes place. This example – or so the objection goes – speaks against the idea of understanding abilities as dispositions to perform certain tasks successfully in certain circumstances. But as some philosophers have correctly pointed out, whether the subject in the example would still have the relevant ability after the amputation is an empirical question, to be answered by the medical and brain sciences Jung & 0ewen , 0öe . At first, it is plausible to suppose she would still have the ability, since the relevant sensorimotor representations in the brain would  Of course, this doesn’t mean that I will actually succeed every time I try to do A; I have the ability to ride a bike, but I still fall every once in a while. The idea of doing A ‘successfully’ is better understood in probabilistic terms: if I have an ability to do A, I am more likely to succeed in A-ing in these A-appropriate circumstances, if I were to try see Millikan : - . This qualification will be omitted from now on, but should be kept in mind.

   The Pragmatic View of Demonstrative Thought I : Practical Knowledge still exist. But without practice these representations would inevitably weaken over time, until the point where she would no longer have the ability in question. As 0oë puts it, practical abilities are embodied, in the sense that they actually change the physical properties of our bodies: sometimes subtly like the way musicians develop calluses in their hand or bike riders enhance their leg muscles, but it can also change neuronal connections in the brain: it is well known, for example, that extensive tool use and practice causes enlarged cortical representations of the hand and arm, and that the loss of limbs leads to deafference of cortical areas and plastic rewiring of the brain 0oë : . The dispositional account allows us to acknowledge this empirical fact. )or some time after the amputation, it is plausible to suppose that the amputee would still have the ability to ride a bike – if she were to try in these circumstances, she would have a disposition to ride a bike successfully. Of course, as things stand she is not in a position to try, but that is a different question. As Millikan points out, we must be careful to distinguish between one having the ability to do A, and one being able to do A : . The exercise of practical abilities depends on certain enabling conditions which are not fulfilled in the amputee’s case. In order to be able to ride a bike, for example, one needs to have access to functioning equipment and suitable terrain, and also have the right bodily properties which enable the successful exercise of A. In other words, the notion of an A-appropriate circumstance is a relational notion, which depends on facts about the agent, the world, and their being appropriately coupled. What happens in the amputee’s case is that she cannot, as things stand, produce a bike riding-appropriate circumstance: some of its enabling conditions are missing. 0evertheless, it’s still the case– at least for some time after the amputation – that if she were to try in the A-appropriate circumstances, she would be disposed to ride a bike successfully. As time progresses she would eventually lose this ability, as the sensorimotor representations that subserve it would weaken without practice. In this case, even if she were to try in the appropriate bike-riding circumstances, she would no longer have a disposition to do so successfully. Her brain would have changed as a result of the amputation, thus causing her to lose the ability in question. If she goes on to acquire prosthetic limbs sometime in the future, she would have to learn the relevant ability all over again through practice. The dispositional account allows us to capture this.

 See also Jung & 0ewen

:

for a similar distinction.

The historical-dispositional account and its limits 

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Moreover, this exact same strategy can also be used to deal with cases where one’s exercise of the relevant ability is hindered by external factors alone. )or example, if in a future dystopia a pro-automobile tyrant destroys every single bike in the world, I would no longer be able to ride a bike. But would I still have the ability to ride one? An answer to this question can be given along the same lines: for some time after the tyrant’s drastic measures I would still have the relevant ability, but without practice I would eventually lose it. So far, it seems that the dispositional account yields the right results and deals successfully with the more problematic cases, but let’s focus on the last part of its definition for a moment: S has a disposition to do A successfully, acquired through practice and learning, if S tried to do so in A-appropriate circumstances. But what constitutes an ‘A-appropriate circumstance?’ I have mentioned that we should understand it as a relational notion, involving facts about the agent, the world, and their being appropriately coupled. But this is not precise enough: what constitutes appropriate bike riding circumstances to me, for example, may not be appropriate circumstances to you at all. If I have only ridden a simple city bike in flat, urban terrain, it would do me no good to have access to a BMX bike in a hilly dirt track. I have no dispositions to ride a BMX bike successfully in these conditions, and if I were to try the results would be disastrous. But these may be ideal bike-riding circumstances to Pierre, who has ridden BMX bikes in hilly dirt tracks all his life. What this suggests is that the notion of an A-appropriate circumstance seems to involve an implicit reference to subjects’ past histories with learning and practicing A. What are A-appropriate circumstances for me are circumstances in which I have learned and practiced A, which are very different from Pierre’s A-appropriate circumstances, which are determined by his own past history with A. In other words, an A-appropriate circumstance is a historical notion, as Millikan rightly points out : . What this means is that, for all subjects S who have the ability to do A, the conditions in which S’s ability to do A would be manifested are conditions in which it was historically designed as an ability: conditions in which it was learned, or naturally selected for. In Pierre’s case, the past presence of BMX bikes and hilly dirt tracks help account for the selection and maintenance of his present ability to ride a bike successfully, while in my case these same circumstances play no such role. )ollowing Millikan’s suggestion, we can then put forward the following historicaldispositional account of practical abilities:

 See Snowdon

for an example along these lines.

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 The Pragmatic View of Demonstrative Thought I : Practical Knowledge

The historical-dispositional account: S has a practical ability to do A = S has a disposition to do A successfully, acquired through practice and learning, if S were to try in circumstances that account for S’s past successes in doing A.

But this is not entirely correct. We cannot equate one’s practical ability to do A with the aforementioned set of complex dispositions. )or if we do so, we’ll end up cutting abilities so finely that there would no longer be any abilities to do A simpliciter, only abilities to do A in some manner or another, in some very definite set of conditions. My ability to ride a city bike in flat, urban terrain, for example, would be different from Pierre’s ability to ride a BMX bike in hilly dirt tracks. And my ability to ride a bike with both hands off the handlebars would be different from the ability to ride while holding on to the handlebars. And so on. Of course, this is not to deny that individuating abilities in this way might be legitimate for some purposes. If during a BMX context I am asked to step up and replace a missing contestant on the tracks, I could legitimately decline on the basis of not having the required ability. But there is also a sense, which our theory should be able to capture, in which there is one ability that both Pierre and I have when we each take our bicycles outside and ride them. This is the sense in which we say that some people have the ability to ride a bike whereas other people don’t, and that the people who have the ability do the same thing. Moreover, the historical-dispositional account would also fail to capture the sense in which I can improve my ability to ride a bike by enlarging the set of circumstances in which I am disposed to ride a bike successfully. If we equate my bike-riding ability with my dispositions to ride a bike successfully in the circumstances in which I have learned it, then if in the future I learn how to ride a bike in a different situation, we would say I have acquired a different ability – not that I have improved my bike-riding ability. And this does not seem right. The historical-dispositional account, by individuating abilities in terms of the specific circumstances in which this ability was learned, seems to yield the wrong results. Rather, what we should say, following Millikan’s lead, is this: abilities are not identical to dispositions but rest on certain complex dispositions of this sort, as stated in the historical-dispositional account Millikan : . That is to say, for every S who has the ability to do A, there will be certain dispositions of S to do A successfully, if S tried to do so in certain circumstances defined by S’s history with A. As S develops her ability through practice and learning, she becomes better in bike riding by enlarging the set of circumstances in which she

The historical-dispositional account and its limits 

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is disposed to do A successfully if she were to try. In other words, she learns how to do the same thing in a wider set of circumstances Millikan : . But the ability is not individuated by these circumstances. If one has the ability to ride a bike in flat terrain and then learns how to go up and downhill, one hasn’t acquired a new kind of ability: rather, one has become better at bike riding, by adding ‘up and downhill circumstances’ to the dispositional set upon which one’s ability rests. But what about practical knowledge? At first sight, it might seem as if one’s practical knowledge of A could be understood in the same manner as one’s practical ability to do A: that is to say, in terms of the dispositional set upon which the ability to do A rests. To have a practical knowledge of bike riding, in this picture, is nothing other than to have the ability to ride a bike in a certain range of circumstances. Correspondingly, one could improve one’s practical knowledge of bike riding in the same way as one becomes better at it: by adding novel circumstances to the dispositional set. This picture, however, is not entirely accurate. )or starters, learning how to do the same thing in various circumstances is not the only way in which one can improve one’s practical knowledge of a certain activity A: in addition, one also learns to recognize better the circumstances in which one would be more or less likely to succeed if one were to try Millikan : . To go back to an earlier example, the reason why I decline the invitation to step up and replace a missing contestant in a BMX competition is that I quickly recognize that this kind of circumstance is not one in which I would be likely to succeed in bike riding, if I were to try. I have accurately identified this circumstance as a risky situation, one where it would be better for me not to try. Adults, for example, fall off their bikes less often than young children, and experienced riders fall less often than novice riders. This is partly because of a difference in sensorimotor coordination, but also because of cognitive differences in risk-assessment. Experienced riders are better at recognizing circumstances that would make bike riding risky, and refrain from doing so in these circumstances. This is different from knowing what to do when riding a bike in various circumstances, and cannot be explained only by the kind of sensorimotor knowledge I deploy in riding successfully in each of these circumstances. It also involves a capacity to recognize a given circumstance as a bikeappropriate/inappropriate circumstance, something that can be accomplished through a variety of means beyond sensorimotor capacities. I can, for example,  )or the sake of simplicity, from now on I shall refer to this set of circumstances as the ‘dispositional set’.

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 The Pragmatic View of Demonstrative Thought I : Practical Knowledge

refrain from riding a certain bike model on the basis of imagining myself riding it and realizing I am too small for it; or I can refrain from riding down a very steep hill based on the sensation of fear that accompanies my visual perception of the hill, which was also present in past situations where I failed; and so on. To conclude, my suggestion is that we think of the relation between practical abilities and practical knowledge in the following way: . One’s ‘practical ability’ to do A rests on certain complex dispositions to do A successfully in certain circumstances those in the dispositional set of A , acquired through learning and practice. As one develops this ability one learns how to do the same thing in various circumstances, thus increasing the dispositional set size. . One’s ‘practical knowledge’ of A encompasses one’s practical ability to do A in each circumstance of the dispositional set, but is not limited to it. It also involves the deployment of other cognitive skills visual and motor imagery, imagination, emotional associations, etc. , which one can bring to bear in order to become better at recognizing other situations that might belong or not to the dispositional set. As one’s practical knowledge develops in this manner, it is endowed with a higher degree of portability and objectivity.

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Two ways of knowing about speed again

In the previous section I have said that a practical ability to do A should not be identified with its particular conditions of manifestation. In other words, that it should be individuated by ends accomplished, rather than means employed. )ailure to do so would make us miss the sense in which one can improve one’s ability to do A by enlarging the dispositional set upon which the ability rests. And the same, of course, goes for practical knowledge: if the ability to do a certain activity A were to be individuated by its particular conditions of manifestation, then our practical knowledge of A would be restricted to the particular circumstances in which it is manifested, and would not be transposable to other situations. But we have just seen that it is possible to improve one’s practical knowledge so as to encompass or exclude other kinds of circumstances. And what I now want to argue is that this is exactly where the orthodox view goes wrong: it tries to persuade us that all practical knowledge is local, non-portable and context-bound, but this is because in the orthodox view practical abilities, and practical knowledge, are individuated by means employed, rather than by ends accomplished.

Two ways of knowing about speed again 

 

To make this point clearer, let’s go back to the orthodox view’s favourite example, involving two ways of knowing about speed. As the example is construed, to have a practical knowledge of the speed one’s travelling – say, at km/h – is to have certain dispositions to make a series of micro-adjustments in response to changing road conditions etc., as one’s driving activity unfolds in time see chapter five, section . . This, however, individuates one’s practical knowledge by means employed rather than ends accomplished: as each circumstance calls for different micro-adjustments, which are manifested differently by subjects with different causal powers, we are naturally led to conclude that practical knowledge of ‘ km/h’ cannot be transposed to situations beyond one’s own experiential awareness of driving. Each person would know ’ km/h’ only as a certain idiosyncratic way of driving, determined by that person’s history of learning and practice. In order to be able to transpose knowledge of a speed to others – or so the orthodox view tells us – we need to conceptualize it: to employ a measuring device like a speedometer, which objectifies the speed in question as ’ km/h’, which can be applied to subjects in a wide range of situations as the same speed. But it is not true that the only way in which we can transpose our knowledge of a speed to others is by conceptualizing it as a number of units. If we individuate practical knowledge by ends accomplished rather than means employed, we will be able to acknowledge other ways in which one’s practical knowledge of speed may be manifested, while still being manifestations of the same activity – namely, traveling at a certain speed, which one can use in order to know what it is for others to travel at this same speed. As one learns to extrapolate one’s practical knowledge of speed beyond one’s idiosyncratic way of driving, one learns to recognize this speed as the same speed through different means. Correspondingly, one’s practical knowledge acquires a higher degree of portability and objectivity. To make this pointe clearer, suppose I am driving at km/h in a brand new )errari on a wide and empty highway, while you are driving at the same speed in an old Volkswagen beetle on a narrow dirt road. Suppose, moreover, that we are driving without looking at our speedometers – in fact, assume them to be broken, so that we have no means at our disposal to know our speed as ‘ km/h’. There are now two questions that come to mind: are we exercising the same ability in driving our respective vehicles at the same speed? Correspondingly, can my practical knowledge of the speed in which I am traveling be used in order for me to know whether you are driving at the same speed? If we follow Cussins and individuate our practical abilities in terms of the series of micro-adjustments we make in order to attain/maintain our traveling

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 The Pragmatic View of Demonstrative Thought I : Practical Knowledge

speed, we are forced to say that we do not exercise the same ability at all. )or we are most likely doing very different things and making very different microadjustments in order to travel at the speed in question, determined by our different vehicles, road conditions and causal powers. So if ‘the same ability’ is what accomplishes the same by the same means, then indeed we are not exercising the same ability at all. Correspondingly, my knowledge of the speed I am traveling will have a subject-specific content, which involves an implicit reference to my own causal powers. In this picture we would each know ’ km/h’ only as subject-relative ways of driving: there is no one speed that we both know as the same speed in our different circumstances. But if we allow that ‘the same ability’ is what accomplishes the same, then there is a sense in which we both exercise the same ability – admittedly, not ‘driving at km/h’, since, by stipulation, we do not know our speed in this manner, as a number of units. But what I’d like to suggest is that even without conceptualizing the speed in this manner, there is a way in which I can attribute my speed to you as the same speed: I can do so on the basis of knowing my speed as ‘this speed’, where the demonstrative picks out not the series of microadjustments I constantly make as I drive, but the rate at which I move through space – something I can apply to others that are moving through space at the same rate, in order to know that there is one speed in which we are both travelling. To make this point clearer, suppose that the dirt road on which you are travelling is parallel to the highway where I am driving my )errari. Suppose, in addition, that we have begun our journeys at the same time, so that we are now travelling right next to one another since we are by stipulation travelling at the same speed . In this case, I could use my visual perceptions of your vehicle as being parallel to mine in order to know that there’s one speed we both have – namely, ‘this speed’, understood as a certain rate of movement through space which I know we both have on the basis of my visual perceptions. This is also a form of practical knowledge of speed, that does not involve conceptualization in units or linguistic articulation of any sort. It also does not presuppose capacities for visual or motor imagery, imagination, iconic memory and other skills associated with what Jung and 0ewen call ‘image-like’ knowledge. It is one way, among others, in which our practical knowledge of  0eedless to say, one is not required to have the concept of ‘speed’, or of a ‘rate of movement in space’, in order to know a speed in this manner; no more than one needs to have the concept of ‘micro sensorimotor adjustment’ in order to know a speed as a way of adjusting oneself to changing circumstances while driving.

Two ways of knowing about speed again 

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speed may acquire a slightly higher degree of portability and objectivity. It’s something I can apply to others who are travelling in a different vehicle in different road conditions, in order to know, on the basis of my visual perception, that there is one speed which we both have. Of course, at this stage of cognitive development my capacities to transpose my knowledge of speed to other circumstances are still very limited, dependent on occurrent visual perceptions and the like. But we can also imagine that as my practical knowledge of speed improves, I become able to recognize a speed as the same speed in different circumstances through different means, in ways that are increasingly less dependent on my actually moving through space at this rate. )or example, if while driving I notice that there are trees placed on the side of the road at certain regular intervals, I could learn to use the rate in which trees pass me by as a way of knowing what it is for others to go at this same speed, in roads with landmarks placed at similar intervals. This is so regardless of whether I myself happen to be moving at this rate. As I have been arguing, this is exactly how we expect practical knowledge to develop: one enlarges the dispositional set size by learning how to do the same thing in various circumstances, and becomes better at recognizing circumstances that belong or not to the dispositional set. Taken together, these capacities will endow one’s practical knowledge of A with a higher degree of portability and objectivity. If I know the speed in which I’m traveling only as a series of micro-adjustments I am continuously making in response to changing circumstances, I have indeed a very primitive form of practical knowledge, with a near-zero degree of portability and objectivity. This is not something I can use in order to know what it is for others to go at this same speed. But we have just seen that my knowledge of speed may develop in such a way that it could become increasingly less dependent on the particular means employed. I can know a speed as ‘this speed’, this rate of movement through space, regardless of which micro-adjustments I happen to make in order to move at this rate. This is something I can apply to others: insofar as two arbitrary objects move at the same rate through space, I can know that they travel at the same speed. My knowledge of speed has acquired a higher degree of portability and objectivity, relative to the initial case where I only know a speed as a series of microadjustments. With these observations in hand, we can begin to lay down the elements for the theory of practical knowledge upon which the pragmatic view shall be built. In the next section of the chapter I will introduce the notion of a ‘cognitive space’, which is central to understanding practical knowledge and its relations to portability and objectivity. My notion of a cognitive space is inspired by Adri-

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 The Pragmatic View of Demonstrative Thought I : Practical Knowledge

an Cussins’ theory of cognitive trails / , but should not be assimilated into it. Cussins’ theory purports to have a much wider scope than the theory of practical knowledge defended in this chapter, and involves a range of theoretical commitments I do not need to make at this point. I will not, however, take the time to make explicit the differences between the two theories. Rather, what I should say is that the theory to follow is inspired by Cussins’ observations concerning cognitive trails, but I make no claims about whether Cussins himself would agree with the details of my proposal.

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The cognitive space

We can begin by conceiving of the dispositional set of A as demarcating a certain zone of competence within the cognitive space of A: the circumstances in which a subject is disposed to do A successfully, if she were to try. Circumstances not in the dispositional set fall outside the subject’s zone of competence regarding A. The main claim to be defended in this section is that practical knowledge of A may be understood as the ability to move in the cognitive space of A in an intelligent and purposeful manner, within a certain zone of competence. To make this idea clearer, we may think of the cognitive space in the model of real space: a certain spatial territory centred on a goal G see below . We can then introduce three different scenarios, which follow the development of an organism’s ability to move in that space. Case : the organism’s practical ability to navigate towards G is very limited, restricted to situations where G happens to be visible from the organism’s point of view. Correspondingly, its zone of competence i.e., the circumstances in which the organism is disposed to reach the goal successfully if it were to try, while moving in an intelligent and purposeful manner is restricted to a narrow band around the goal G, from which G can be perceived figure .

 This qualification is needed in order to exclude cases where the organism is outside its zone of competence but happens to stumble upon the goal by pure luck.

The cognitive space 

)ig.

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: Illustration of a limited zone of competence within a certain space from Cussins 99

Case : the organism develops its G-finding abilities. In addition to situations where G happens to be visible from the organism’s point of view its initial zone of competence , the organism now has the ability to reach G on the basis of locating a certain landmark L it has learned to associate with G. So when the organism is located in a spatial position from which L is visible, it can first navigate to L and then to its final destination G. In this case, the organism has added more circumstances to the dispositional set; it is disposed to reach G successfully not only when it is able to perceive G, but also when it is able to perceive L from which G should be visible . As the organism gradually learns to make use of various landmarks in its external environment, its ability to find G is largely improved: it can also reach G by first locating another landmark L from which L is visible, and then, on this basis, navigate towards G. The organism’s zone of competence is correspondingly expanded, as illustrated in figure below:

)ig.

: Intermediary zone of competence within a certain space from Cussins 99

   The Pragmatic View of Demonstrative Thought I : Practical Knowledge

Case : the organism becomes sufficiently familiarized with its environment, so that it will eventually have the ability to find G no matter where it is located in the environment figure . One way to understand this improvement of the organism’s G-finding abilities is to say that it has added more and more circumstances to the dispositional set, thus expanding its zone of competence to cover the entire territory. By doing this, its ability to find G becomes increasingly less dependent on the organism’s conting ent position in space or its perceptual perspective upon G.

)ig.

: Maximal zone of competence within a certain space from Cussins 99

With these elements in place, we can now explain the organism’s practical knowledge of its environment relative to a goal G in terms of its abilities to move intelligently and purposefully towards G from any arbitrary point located within its zone of competence. As we have seen by comparing the three cases above, these abilities may be improved by expanding the zone of competence. As one adds more circumstances to the dispositional set, one becomes able to find G in a wider range of circumstances, from a larger number of points in the spatial territory around G. And what I would like to suggest is that we can generalize this account in order to cover non-spatial abilities as well. In this picture, to have a practical knowledge of a certain activity A is to have the ability to move in the cognitive space of A in an intelligent and purposeful manner, within a certain zone of competence. As before, this ability may be improved by  As Cussins puts it, in this case its zone of competence regarding G “…has spread to fill the whole territory. There are no “privileged” positions within the space such that the [organism] must start at one of the privileged positions in order to locate the goal, or must proceed to a privileged position in following a route to the goal. The best case is that in which there are no privileged positions wherever the goal is located Cussins : .

The cognitive space 

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adding more circumstances to the dispositional set, thus expanding the zone of competence. To make this point clearer, take each circle represented in figure see page as a circumstance in the dispositional set: a situation where one is likely to succeed in A if one were to try. Taken together, these circumstances the entire dispositional set constitute the zone of competence of the organism within a cognitive space: the set of circumstances in which it is disposed to do A successfully, if it were to try. As one gradually expands one’s zone of competence by adding more circumstances to the dispositional set, one becomes a better navigator in cognitive space. One can succeed in doing A no matter where in one’s zone of competence one happens to be located, and recognize other circumstances within the zone of competence as A-appropriate circumstances as illustrated in fig. above . In this picture, to have a practical knowledge of A is to have an ability to move intelligently and purposefully in this cognitive space, much like in the spatial scenario above. Except that in this case, the movement is of course metaphorical, and should be understood relative to one’s zone of competence: from whatever point in the zone of competence one happens to be i.e., in any circumstance of the dispositional set , one will have a disposition to do A successfully if one were to try, and one will become able to recognize other situations as A-appropriate or inappropriate situations. One would know how to move within the zone of competence without getting lost , i.e., without wandering beyond its boundaries. The more circumstances one adds to the dispositional set through learning and practice, and the better one is at recognizing A-appropriate and inappropriate circumstances, the more one develops one’s practical knowledge of A. This knowledge is gradually endowed with a higher degree of portability and objectivity, being increasingly less dependent on the subject’s particular position in the cognitive space. To connect this point with our previous discussion: in the last section of the chapter I have said that we could use our practical knowledge of a certain speed in order to know what it is for another subject to travel at this same speed. We can now translate this idea in the vocabulary of the cognitive space: to say that one has a practical knowledge of ‘ km/h’ as a series of micro-adjustments is to say that one has the ability to move in the cognitive space of ’ km/h’ only within a very restricted zone of competence: more specifically, in circumstances where one is actually making the series of micro-adjustments required for one to attain/maintain the speed in question. The situation here would be similar to ‘case ’ of the spatial scenario above, where an organism can find the goal G only when G is visible from its point of view.

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 The Pragmatic View of Demonstrative Thought I : Practical Knowledge

In contrast, to have a practical knowledge of ‘ km/h’ as a rate of movement through space is to have an ability to move in the cognitive space of ‘ km/h’ within a wider zone of competence, that is no longer dependent on the contingent micro-adjustments one makes in order to move at this rate. )or now one’s zone of competence of ‘ km/h’ has expanded so as to include circumstances where other objects move through space at this same rate, even if they deploy different means in order to do so. The situation here would be comparable to ‘case ’: the subject has expanded its zone of competence, but it is still dependent on her occupying certain privileged positions within that cognitive space. Circumstances where one cannot visually perceive this rate of movement, for example, are outside the zone of competence. There is an obvious connection between the expansion of the zone of competence regarding A and the degree of portability and objectivity of one’s practical knowledge of A. Take the case where one has a practical knowledge of ‘ km/h’ as a rate of movement through space, which one can apply to other objects who move at the same rate even if they do so through very different means . When one is able to extrapolate one’s knowledge of speed in this manner, one learns how to abstract away from the particular means employed in one circumstance or another, and comes to represent this speed as the same speed in a wider range of circumstances. As we widen our zone of competence within the cognitive space, we become better at distinguishing idiosyncratic means from ends, and learn to recognize the same activity as such from different perspectives and situations, even if some of the means which we normally employ in order to accomplish it happen to be missing. This endows our practical knowledge of A with a higher degree of portability and objectivity, as it becomes increasingly less dependent on our causal powers and means of choice. So now that notions of the ‘cognitive space’ and the ‘zone of competence’ have been made clearer, we can propose the following account of practical knowledge: . To have a practical knowledge of A is to have an ability to move in the cognitive space of A in an intelligent and purposeful manner, within a certain zone of competence. . This zone of competence may be expanded by adding novel circumstances to the dispositional set of A. . As the zone of competence expands, one’s practical knowledge of A improves: one increases the number of circumstances in which one is disposed to do A successfully, and which may be recognized as Aappropriate circumstances from any other point within the zone of com-

Stabilization and movement in cognitive space 

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petence. Correspondingly, one’s practical knowledge of A will acquire a higher degree of portability and objectivity. But we must now add an important qualification. Based on what’s been said so far, one might think that to endow one’s practical knowledge of A with a higher degree of portability and objectivity is nothing more than to add more and more circumstances to the dispositional set of A. In this picture, if we were to represent the relation between degree of portability and objectivity and dispositional set size, the resulting graph would look something like this:

)ig.

: Simple relation between portability, objectivity, and dispositional set size

This, however, wouldn’t be entirely correct. As we shall see in the next section, the degree of portability and objectivity of one’s practical knowledge of A is determined not only by dispositional set size but also by one’s capacity to ‘stabilize’ certain features of one’s experience with A, so as to make them more easily portable from one situation to the next.

. Stabilization and movement in cognitive space Adrian Cussins borrows the notion of ‘stabilization’ from Bruno Latour’s idea of ‘blackboxing’ , a process which takes some unstable phenomenon in flux and builds a box around it, so that it can enter cognition as a single unit. Latour’s example involves a transition from a complex and effortful use of an early Kodak prototype to the instantaneous, automatic process of taking photographs we employ today with modern cameras. Here’s Latour: The [early] Kodak camera is made of bits and pieces, of wood, of steel, of coating, of celluloid. The semi-professionals of the time open up their camera and do their own coating

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 The Pragmatic View of Demonstrative Thought I : Practical Knowledge

and developing, they manufacture their own paper. The object is dismembered each time a new photograph is taken, so that it is not one but rather a bunch of disconnected resources that others may plunder. 0ow the new Kodak automatic cannot be opened without going wrong. It is made up of many more parts and it is handled by a much more complex commercial network, but it acts as one piece... So it is not simply a question of the number of allies but of their acting as a unified whole. With automatism, a large number of elements is made to act as one … . When many elements are made to act as one, this is what I will now call a black box. Latour : - , quoted in Cussins : –

With stabilization, all the different micro-adjustments that earlier photographers needed to perform in order to compensate for different lighting conditions etc. become stabilized into a single act. The modern user pushes the indicated button, and all operations are performed automatically by the camera’s operating system. So whereas before one’s knowledge of photo shooting was difficult to transpose from one situation to the next – knowing how to take pictures in bright sunlight, for example, was very different from knowing how to take pictures at dawn or in a dark cloudy afternoon – stabilization hides all these micro-adjustments within a blackbox and automatizes them as a single act. This allows the modern user to engage in photo shooting in practically any kind of circumstance, without having to know how to perform the micro-adjustments made automatically by the camera. Stabilization makes unstable phenomena portable by building a blackbox around it, allowing the subject to easily carry it and deploy it in various circumstances. But automatization is not the only way in which stabilization might take place. To go back to our earlier example, when we have a practical knowledge of ‘ km/h’ as a certain rate of movement through space, we take all the microadjustments that would be required in order for one to travel at this rate and stabilize them as a unit: ‘this speed’, this rate of movement through space. This allows us to abstract away from idiosyncratic differences in micro-adjustments and use this perceived rate of movement as a unit, which is freely applicable to any object that we may visually perceive as moving at this rate through whatever means . In addition, stabilization may occur successively at different levels. At the bottom level some features may be stabilized together and blackboxed as a unit. Then, this unit becomes part of a further act of blackboxing, becoming stabilized with other features as part of a higher-order unit, and so on. To illustrate with an example, imagine that at some point in history people acquired the skill of making chicken broth, by boiling chicken bones for a few hours along with some vegetables and spices. Once the process became more-or-less mastered, it could then become stabilized and enter a cookbook as a blackboxed unit: to

Stabilization and movement in cognitive space 

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make tomato soup, take one can of chicken broth… . Regardless of the details of the cooking process, blackboxing ‘chicken broth’ allows less experienced cooks to prepare recipes that depend on the use of chicken broth: all one needs to do is go to the nearest supermarket and acquire a can that reads ‘chicken broth’. Then, we can also imagine that as the process of making tomato soup is mastered, it becomes stabilized and blackboxed as a unit: to make Indian chicken makhani, mix one cup of tomato soup… , and so on at successive levels of the hierarchy serve each guest with one portion of chicken makhani… . This suggests that there are two relevant dimensions to consider when we ask for the degree of portability and objectivity of one’s practical knowledge of a certain activity A – ‘stabilization’ and ‘dispositional set size’. By increasing dispositional set size and stabilizing certain features of our experience with A as a unit, our practical knowledge of A becomes endowed with a higher degree of portability and objectivity. This gives us a more complex representation of the relation between these various elements, which may be illustrated in the graph below:

)ig. : Simple relation between stabilization, portability, objectivity, and dispositional set size.

In this picture, the highest level of objectivity is achieved by gradually increasing the dispositional set size and stabilizing features at increasingly higher levels of abstraction, until one comes to occupy the zone of maximal objectivity represented in the graph. Such a process may be observed, for example, in philosophical theorizing: throughout this chapter I have taken a range of skilful, embodied activities and stabilized them under the notion of ‘practical knowledge’, so that a certain theory could be built in order to explain it ‘the cognitive space’ . This theory then enters a larger theoretical framework as a unit ‘the pragmatic view’ , which is eventually stabilized along other theories

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 The Pragmatic View of Demonstrative Thought I : Practical Knowledge

at a higher-level analysis ‘pragmatist views of singular thought’ . The higher we climb, the more detached and disengaged our picture of the world will be, as it becomes increasingly less dependent on our actual embodied practices and experiential awareness of the activity or range of activities we theorize about. The ability to move through cognitive space, one might think, is evaluated by its orientation towards the zone of maximal objectivity: the right way , as it were, is always upward and forward. This, however, would not be right. As Cussins rightly points out : , one’s ability to move through cognitive space of A cannot be measured only upwards and forward, by the capacity to increase dispositional set size and stabilize features at increasingly higher levels of abstraction. Rather, a skilful navigator of cognitive space is one who knows when to re-open the blackbox and renegotiate previously stabilized features whenever the need arises. Early scientists have stabilized certain natural phenomena in certain ways along with other phenomena, which modern science often needed to de-stabilize and restabilize again in a different way in order to make progress. To illustrate with an example, certain physiological features of the human skull became stabilized with certain observable psychological traits, giving rise to the field of phrenology. After some time, however, the weak predictive power of phrenology betrayed its scientific status. The blackbox was then re-opened, and features destabilized. At this point, the dispositional set size associated with certain activities for example, the identification of psychopaths actually decreases, as it is no longer clear which features generalize from one case to another. Modern psychology then proposes alternative ways to stabilize features, leading to the construction of a new feature-space at a higher level which may be subject to further processes of de-stabilization whenever they conflict with empirical data . De-stabilization is also present in more mundane cases, like our previous cooking example. A good cook is someone who can not only stabilize cooking processes and mechanisms, but can also de-stabilize them in a systematic manner: to reopen the blackbox of ‘chicken broth’ or ‘tomato soup’, for example, and experiment with new ingredients and methods until a more suitable result is obtained. Then, these new features may be blackboxed together again as a new feature-space, which soup companies may advertise as a new kind of tomato soup. When soup companies compete over the best product, they actually compete to see which one has the best blackbox – the package that most often leads to desirable outcomes without having to be constantly de-stabilized. This suggests that one’s practical knowledge of a certain activity A – in the present terminology, one’s ability to move through the cognitive space of A in

Stabilization and movement in cognitive space 

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an intelligent and purposeful manner, within a certain zone of competence – should not be understood simply as a way of moving forward and upwards along the dimensions of stabilization and dispositional set size. On the contrary, to have the ability to move in cognitive space is to be suitably sensitive to circumstances which call for de-stabilization, and for a reduction of dispositional set size. As I’ve said before, one of the ways in which one’s ability to do A could be developed is by learning to recognize better the circumstances in which one would more or less likely to succeed, if one were to try. Sometimes this implicates an increase in dispositional set size, as one learns how to do A successfully in a novel circumstance which one has identified as an A-appropriate circumstance. But this should not blind us to the fact that this development often takes the form of a de-stabilization and decrease in dispositional set size. )or example, when one identifies a situation that was previously included in the dispositional set as being ill suited for the practice of A. This might lead to destabilization, especially if there is a conflict between the stabilized featurespace and the exclusion of the circumstance in question the blackbox should be normally applicable to this kind of situation, but we have just discovered it is not: what has gone wrong? . To conclude, the degree of portability and objectivity of one’s practical knowledge of A cannot be identified with an orientation towards a privileged region in cognitive space, achieved by a gradual and constant increase in dispositional set size and higher levels of stabilized feature-spaces. On the contrary, what these observations suggest is that there are no privileged positions from which one enjoys a maximally ‘objective’ perspective upon the world: portability and objectivity are measured by one’s ability to move in cognitive space in an intelligent and purposeful manner, that is, to increase and decrease dispositional set size, to stabilize and de-stabilize feature-spaces, and so on. Rather than aiming for a privileged region of cognitive space with the highest measurements of dispositional set size and stabilization, one aims for successful navigation by knowing how to spiral back and forth along these two dimensions. In contrast with the previous graph depicting portability and objectivity in relation to dispositional set size and stabilization, we would now have the following more complex spiral:

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)ig.

 The Pragmatic View of Demonstrative Thought I : Practical Knowledge

: More complex relation between stabilization and dispositional set size

This, in short, is the notion of practical knowledge I will presuppose in the pragmatic view: practical knowledge as a way of moving spiralling in cognitive space in an intelligent and purposeful manner, within a certain zone of competence, along the dimensions of stabilization and dispositional set size. To improve one’s practical knowledge, in this picture, is to become better at moving in this space; to be suitably sensitive to both stabilization and dispositional set size, knowing when to de-stabilize and decrease dispositional set size when the need arises. )or example: as one learns how to do the same thing in different circumstances, one’s repeated success with A might lead to stabilization, and to the construction of a novel feature-space which abstracts away from the particular means employed in each circumstance. But at some point a conflict might arise, and the stable feature-space that should be normally applicable to one kind of circumstance turns out to be inappropriate. Thus, the blackbox is re-opened, dispositional set size decreased, and a new feature-space construed. By learning how to move in the cognitive space of A in this manner and balancing these two dimensions, one’s practical knowledge of A acquires a higher degree of portability and objectivity: one learns how to stabilize landmarks within the zone of competence in a more efficient manner, leading to a more stable expansion of the zone of competence and a more robust ability to move through it. )or a landmark is, precisely, a way of stabilizing certain features of the external environment in order to expand one’s zone of competence in it. Correspondingly, some ways of stabilizing features for this purpose are better than others: transient features, or features that are easily destroyed, do not make good landmarks; that is why dropping bread crumb trails is a terrible way of demarcating a path, as illustrated in the classic tale of Hansel and Gretel by the

Stabilization and movement in cognitive space 

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Brothers Grimm. In a similar vein, some features are better at helping us recognize A-appropriate or inappropriate circumstances, and may become stabilized in the form of a landmark , which expands our zone of competence within the cognitive space of A. This will be especially important when we apply this theory to our practical knowledge of objects in chapter seven. According to this proposal, we do not need to supplement practical knowledge with conceptual knowledge, because practical knowledge is already able to provide us with enough ‘room for manoeuvre’ in cognitive space, as the zone of competence expands so as to encompass a wider range of circumstances. So now that we’re in possession of a theory of practical knowledge, we are finally in a position to apply it to our object of study: singular object representation. This will lead to the ‘pragmatic view of demonstrative thought’ to be defended in chapter seven, where singular object representation will be explained in terms of a practical knowledge of what objects are and how they behave, in accordance with the theory of practical knowledge defended in this chapter.

 The Pragmatic View of Demonstrative Thought II : Object Representation .

Introduction: practical knowledge and object representation

We now arrive at the final stage of our investigation, where we are finally in a position to answer the questions laid out in chapter one, namely: how can we explain our capacity to engage in object-directed mental activities with singular demonstrative contents? What cognitive capacities underlie it? In chapter one we looked at two constraints that any theory of singular demonstrative representation should be able to meet, which was supplemented by a third in chapter four. These are summarized below: . Individuation: singling out something as an object requires one to be able to spatially discriminate the object from its neighbours and from the background. . Maintenance of 0umerical Identity: singling out something as an object requires one to keep track of its spatiotemporal trajectory, continuously representing it as the same object through time and motion. . Spatial Significance: singling out something as an object requires that the object have an egocentric location for the subject, that it acquires spatial significance for her. According to the perceptualist approach to demonstrative thought, we can account for all these constraints at the more primitive level of perception. The resulting theory, as presented in chapter four, can be summarized in table , repeated below for ease of exposition: Tab. : Basic elements of a perceptualist theory of demonstrative thought Individuation

Pre-attentive processes of object segregation Vecera

Maintenance of 0umerical Identity

Attentional Selection Rensink

Spatial Significance

Practical sensorimotor knowledge of the behaviour of three-dimensional objects in a three-dimensional environment Evans , O’Regan & 0oë

Introduction: practical knowledge and object representation 

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We have then seen the ‘conceptualist challenge’ to this theory: there is an epistemic dimension to demonstrative thought implicit in the singular element of the content of these thoughts, which perceptualism leaves unexplained. Ascriptions of singular content should reflect the subject’s capacity to apprehend her external environment as structured into individual objects, but there is nothing in the perceptualist theory above that suggests this might be the case. Although a subject who meets all three constraints above is certainly able to engage in mental activities directed at what are in fact objects, there is no reason to ascribe singular contents to her mental states. In other words, perceptualism successfully accounts for the semantic, demonstrative element of the content of demonstrative, but leaves the epistemic, singular element unaccounted for. But even granting this point should not necessarily lead us into conceptualism. One obvious alternative, which would maintain the overall project of explaining object representation without appealing to more sophisticated forms of conceptual understanding, would be to capture this epistemic element with a practical knowledge of objects: a practical sensitivity to what objects are and how they behave, which would dispense with the kind of reflective, detached understanding that is characteristic of conceptual knowledge. Before we could begin to put this view forward, however, we were first required to dispense with the ‘orthodox view’ of practical knowledge, and propose a novel account which does not confine practical knowledge to more primitive forms of sensorimotor abilities. This is was the main goal of chapter six, where a theoretical alternative was proposed based on the notion of the ‘cognitive space’. To have a practical knowledge of a certain activity or subject matter A, in the new proposal, is to have a capacity to move in the cognitive space of A in an intelligent and purposeful manner, within a certain zone of competence. This metaphorical navigational skill encompasses a range of interconnected abilities, namely: . To have dispositions to do A successfully in each circumstance of the dispositional set, if one were to try; . To be disposed to recognize other circumstances in the zone of competence as an A-circumstance, from other points within that zone; . To be able to expand the zone of competence by adding novel circumstances to the dispositional set; . To be able to recognize the boundaries of the zone of competence, and not venture to circumstances which are unlikely to support successful Aactivities;

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 The Pragmatic View of Demonstrative Thought II : Object Representation

To stabilize certain features of circumstances in the dispositional set and blackbox them as a unit; To be sensitive to circumstances in which one is required to de-stabilize features and re-stabilize them again perhaps in a different manner .

I have put special emphasis on ability , which allows one to apply one’s practical knowledge to other circumstances in a more efficient manner, by abstracting away from idiosyncratic differences among circumstances which have been hidden inside the blackbox . One example of this ability is the case where one comes to have a practical knowledge of a speed as a certain rate of movement through space. This allows one to understand that two objects moving at the same rate will have the same speed, regardless of the particular means through which they maintain this speed. This endows one’s practical knowledge with a higher degree of portability and objectivity. But I have also insisted, following Cussins , that for one’s practical knowledge to improve in this manner is not only for one to stabilize features at increasingly higher levels of abstraction and to continuously increase the dispositional set size, but also to be sensitive to circumstances in which one is required to reopen the blackbox and renegotiate features, only to stabilize them at a subsequent stage ability . But I grant that this may all be quite abstract at this point, and the reader is possibly wondering how this framework is supposed to apply to the particular case of object representation. What would a pragmatic view of demonstrative thought look like, structured in terms of practical knowledge? This chapter will be dedicated to clarifying this question, applying the theory of practical knowledge developed in chapter six to the problem of object representation, while having the conceptualist challenge in mind. This will be done in two stages: I’ll start by introducing José Luis Bermudez’s ‘object properties model’ of object perception / , which seeks to explain object representation in terms of practical knowledge of certain physical principles and regularities that govern the behaviour of three-dimensional objects. In order to be able to represent an object, Bermudez tells us, one needs to be suitably sensitive to certain canonical properties of objects, which he explains in terms of practical knowledge. But as we shall see, the way Bermudez cashes out practical knowledge – in terms of perceptual sensitivity to these properties as they are

Bermudez’s object properties model of object perception 

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instantiated in one’s experience – leads us into the same problems we have encountered before, and is unable to meet the conceptualist challenge. Therefore, the next step will be to combine Bermudez’s theory with the present account of practical knowledge, allowing it to develop beyond mere perceptual sensitivity to canonical object properties. In this picture, perceptual sensitivity will be presented as the initial state of our practical knowledge of objects, but as our knowledge develops we learn to recognize these properties in a wider range of circumstances and under different modes of presentation. In this manner our knowledge acquires a higher degree of portability and objectivity, eventually extrapolating to non-perceptual contexts as well. We can explain how this development proceeds within the very same framework Bermudez draws upon, based on Yuko Munakata and collaborators’ connectionist modelling of object representation within a framework they call the ‘graded knowledge approach’. In this framework, one’s gradual understanding of object persistence is explained in terms of neural connections in the prefrontal cortex which represent the object in question that progressively strengthen as a function of experience. This allows us to represent an unperceived object like a visible object, that is to say, in terms of a strong representation in the prefrontal cortex that may be actively sustained independently of any actual perceptual input from the object, in an increasing number of contexts and for increasingly longer periods of time. This will allow us to meet the conceptualist challenge without having to appeal to more sophisticated forms of conceptual knowledge.

. Bermudez’s object properties model of object perception In chapter four we saw that there is more to object representation than preattentive processes that segregate perceptual units in a visual array, and attentional processes that maintain their numerical identity in time for a period of observation. Real three-dimensional objects give rise to a feeling of spatiotemporal connection, something our theory should also be able to explain. They are  To be fair, it’s not Bermudez’s goal to answer the conceptualist challenge. The object properties model is put forward as an alternative to the ‘theoretical model’ of object perception in young infancy put forward by Gopnik and Meltzoff . According to this model, infants’ knowledge of objects should be explained in terms of their implicit knowledge of a theory of the physical principles that govern the behavior of objects. In the context of this debate, it is not required that Bermudez’ account be extended to other cases beyond perceptual sensitivity. Munakata et al. , Munakata & McClelland , Munakata .

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 The Pragmatic View of Demonstrative Thought II : Object Representation

perceived as things we are spatiotemporally connected to, things that have spatial significance to us. Mohan Matthen suggested that this is because real objects get to be processed by motion-guiding vision, but we have already seen that this cannot be right. Motion-guiding vision can only engage objects in near space, but objects beyond near space also have spatial significance to us. A much more promising proposal is to explain spatial significance in terms of our having sensorimotor knowledge of certain physical principles that govern the behaviour of threedimensional objects in a three-dimensional environment, acquired through repeated patterns of interactions with objects in space. )or example, objects tend to have well defined edges relative to the environment; they do not usually exhibit great variations in shape or size, and maintain certain forms of perceptual constancy when they move relative to the perceiver; they move in a spatiotemporally continuous manner, independently from one another, and do not pop in and out of existence; they exert and are subject to force, and have a certain mass that governs their interactions with other objects; they are subject to gravity and fall when unsupported; and so on. If something fails to be subject to these regularities – as the case of unreal ‘objects’ like phosphenes or afterimages, or objects depicted in a picture – it will not have spatial significance to us, it will not give rise to the feeling of spatiotemporal connection, and we will not be able to single it out as an object. As Bermudez puts it, Genuine objects obey certain principles and behave in certain regular ways. A world articulated in terms of genuine objects is a world that obeys certain basic physical regularities. Consequently, any creature that perceives such a world must be sensitive to these physical regularities that circumscribe what it is for something to count as a particular or a body at all. Bermudez :

Research on object cognition in early infancy has been particularly fruitful in uncovering these principles, and determining, mainly on the basis of the dishabituation experimental paradigm, the age in which infants begin showing sensitivity to them. The basic presupposition behind the dishabituation paradigm is that infants look longer at events they find surprising, that somehow violates their expectations. So if we habituate them to a given event and then show them another event that differ from the habituated one in certain determinate and carefully controlled ways, we should be able to detect the specific features they are sensitive to. We have already seen an example of this strategy before, when discussing an experiment designed by Spelke and collaborators involving qualitatively identical rubber ducks being alternately presented as coming out from

Bermudez’s object properties model of object perception 

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behind two spatiotemporally discontinuous barriers. When at the end of the experiment both barriers are lifted, infants are surprised if the final outcome reveals only one object rather than two. )rom these results, we can conclude that infants in the experiment are already sensitive to the principle that objects do not simply pop in and out of existence, but trace continuous spatiotemporal paths: an object could not have moved move from a point A to another point C without passing through a visible intermediary point B. In another classical experiment designed by Renée Baillargeon , . to o . month-old infants were habituated to seeing a screen rotating on a table. The experimenter would then place, under the full view of the infant, an object behind the screen. What Baillargeon found was that infants were suro prised if they saw the screen rotating on the table, rather than stopping at the point where it was expected to come in contact with the occluded object figure . This strongly suggests that infants at this age are already sensitive to the principle of object permanence, expecting that an object that has been temporarily hidden continues to exist unperceived behind the screen.

)ig.

: Experimental design for object permanence in young infants from Baillargeon 9

The examples multiply. In another famous experiment conducted by Kotovsky & Baillargeon , . to . month-old infants were habituated to the event depicted in the top display of figure below, where a medium-sized cylinder rolls down a ramp and sets a medium-sized sphere in motion. If following ha-

 See chapter five, section . .

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 The Pragmatic View of Demonstrative Thought II : Object Representation

bituation they are presented with the ‘smaller’ rather than the ‘bigger’ condition depicted in the bottom displays, they are surprised Kotovsky & Baillargeon , Saxe & Carey . This is, once again, evidence that at this age infants are already sensitive to the principle that objects exert and are subject to force, and that they have a certain mass that governs their interactions with other objects.

)ig. : Experimental design for the perception of causality in young infancy from Saxe & Carey 6

Based on these observations, Bermudez’s idea is that our practical knowledge of these principles can be explained in terms of a perceptual sensitivity to what he calls ‘canonical object properties’, which are constitutive of something qualifying as an object. These properties correspond to the physical principles and regularities mentioned above, for example: . The property of following a continuous spatiotemporal trajectory . The property of having a determinate shape . The property of continuing to exist when unperceived . The property of being homogenous and internally unified . The property of being impenetrable . The property of being subject to gravity . The property of being internally causally connected . The property of having a certain mass . The property of posing resistance to touch . The property of causally influencing other objects, etc.  See Bermudez : . As Bermudez points out, this list is far from being exhaustive or fixed: some objects like air balloons are not subject to gravity in an interesting sense, while

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So what would it be for one to be ‘perceptually sensitive’ to the fact that these properties apply to an object? )irst of all there is an obvious behavioural criterion, measured by looking times in the dishabituation experimental paradigm. That is to say, if an infant is surprised when one of these physical principles is violated, then we may ascribe her a perceptual sensitivity to the fact that the corresponding canonical property applies to the object. The behavioural criterion, however, does not tell us very much. How is this perceptual sensitivity structured? How do infants use their practical knowledge of these properties in order to guide their behaviour appropriately? Do they need to internalize and store them as a set of theoretical principles, which would be accessed whenever the infant is faced with what may be an object, in order to generate the appropriate behavioural output? That would not be very plausible. As I have mentioned before fn. , one of Bermudez’s main motivation in explaining practical knowledge in terms of perceptual sensitivity is precisely to offer an alternative to the theoretical model of object perception put forward by Gopnik and Meltzoff , according to which infants’ knowledge of objects should be explained in terms of their knowing a theory of the physical principles that govern the behaviour of objects. But if these principles are not internalized and stored as a set of rules, how are they guiding the infant’s behaviour in the appropriate manner? In order to explain how this is possible Bermudez appeals to Yuko Munakata and collaborators’ connectionist model of infant cognitive development, which also purports to be an alternative to the theoretical model of Gopnik and Meltzoff. Here’s how the authors put it: Because infants seem to behave in accordance with principles at times, there might be some use to describing their behavior in these terms. The danger, we believe, comes in the tendency to accept these descriptions of behavior as mental entities that are explicitly accessed and used in the production of behavior. That is, one could say that infants’ behavior in a looking-time task accords with a principle of object permanence, in the same way one could say that the motions of the planets accord with Kepler’s laws. However, it is a further – and we argue unfounded – step to then conclude that infants actually access and reason with an explicit representation of the principle itself. We present an alternative

 others may alter their shape dramatically in regular ways like a Brazilian three-banded armadillo that can curl into an almost perfect sphere . Moreover, some of these properties like being resistant to touch may plausibly be reduced to other properties like being impenetrable . In any case, these are properties that structure our knowledge of objects in a general manner; as we shall soon see section . , part of what it is for our practical knowledge of objects to improve is precisely to be sensitive to the various ways in which they apply or fail to apply .

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 The Pragmatic View of Demonstrative Thought II : Object Representation

approach that focuses on the adaptive mechanisms that may give rise to behavior and on the processes that may underlie change in these mechanisms. We show that one might characterize these mechanisms as behaving in accordance with particular principles under certain conditions ; however, such characterizations would serve more as a shorthand description of the mechanism’s behavior, not as a claim that the mechanisms explicitly consult and reason with these principles. Munakata et al. : , quoted in Bermudez :

Their proposal is that the principles that we, as theorists, attribute to the contents of infants’ ‘practical knowledge’ are not explicitly stored in the form of theoretical principles. Rather, they are implicitly stored in graded patterns of neural connections that gradually strengthen as a function of experience. To make this point clearer let’s take the principle of object permanence, which corresponds to the property of objects to continue to exist when unperceived. In Baillargeon’s experiment with the rotating screen, we have seen that . / . month-olds already expect that an object that is temporarily hidden from view will continue to exist unperceived, manifested in longer looking times when the o barrier rotates . In Munakata’s framework, these expectations reflect the persistence of patterns of neuronal activation i.e., object representations that accompany our visual experience of objects. As infants routinely observe objects being occluded and coming into view again, the connections between the neurons that represent the object are strengthened, allowing the representation to persist during occlusion. )igure below shows an occlusion event top display serving as input to a neural network bottom display . As the network is exposed to repeated instances of the occlusion event, it learns to make the correct predictions at each step, on the basis of a memory of the input at the previous step. As a consequence, the connections between the relevant neurons are strengthened, and the network becomes increasingly more efficient in predicting the reappearance of the occluded object at the last step over increasingly longer periods of occlusion. The network is, in effect, learning how to maintain an object representation through occlusion Bermudez : – .

 The authors explain learning in the neural network as a process driven by discrepancies between the predictions that the network makes at each time step and the input it receives at the next time step. The correct prediction at one time step corresponds to the input that arrives at the next time step.” Munakata et al. :

Bermudez’s object properties model of object perception | 231

Fig. 29: Representation of occlusion events in neural networks (from Munakata et al. 1997)

This allows us to explain infants’ understanding of object permanence without having to appeal to theoretical principles that are explicitly stored and accessed. When we, as theorists, ascribe to infants a perceptual sensitivity to the property of continuing to exist when unperceived, in Munakata’s framework this sensitivity is a function of the network’s accuracy in predicting the object’s reappearance after occlusion. At each successful prediction the relevant connections are strengthened, allowing the object representation to survive increasingly longer periods of occlusion. Interestingly, this model can also be used to explain empirical results found by Johnson et al. (2003). Using corneal reflection eye-tracking technology to record 4 month-olds eye movements, Johnson et al. were able to identify two types of saccadic movements infants make in occlusion events: anticipation movements, where the infants’ eyes move to the far end of the occluder before the emergence of the object, and reaction movements, where they move to the far end of the occluder more than 200ms after the emergence of the object. What the authors found is that even very brief training periods with various kinds of occlusion events already cause dramatic changes in 4 month-olds objectdirected saccades, resulting in significantly more (and faster) anticipation movements.6 Once again, this may be explained in Munakata’s framework: repeated exposures to occluding events during the training period strengthens the relevant neural connections, making the network increasingly more efficient in predicting the object’s reappearance at the other end of the occluder. A correlate of this increasing efficiency is infants’ faster anticipatory saccades to the location where the object is expected to reappear. Moreover, the account can easily be generalized in order to cover other canonical object properties as well. Take, for example, the property of being sub-

|| 6 Johnson et al. 2003. See also Gredebäck et al. (2010) for a detailed description of corneal reflection eye-tracking technology, as well as its applications to various domains of infant cognition such as visual attention, perceptual completion, social cognition, etc., and Scholl 2004 for general discussion.

   The Pragmatic View of Demonstrative Thought II : Object Representation ject to gravity. Imagine a visual input consisting of an object x that rests on top of another object y which is suddenly removed, leading to x’s fall. Just like before, we could also explain one’s perceptual sensitivity to this canonical property in terms of the network’s accuracy in predicting x’s downwards movement upon removal of its support y. In the case of the property of exerting and being subject to force, we could also explain perceptual sensitivity in terms of the network’s accuracy in predicting the forward movement of a propelled object upon physical contact with a propeller. And so on. With these ideas in mind, we can put forward the ‘object properties model of object perception’: in order to be able to perceive an object, one is required to have a practical knowledge of certain physical principles and regularities that govern the behaviour of three-dimensional objects in three-dimensional space. This much we have already seen in the perceptualist theory developed in chapter four. Bermudez’s innovation, however, is to explain this practical knowledge through a perceptual sensitivity to a range of canonical object properties, which can be accounted for in terms of neural networks’ predictive successes in various object-directed tasks. As learning in neural networks is a gradual process, this model can explain how infants’ practical knowledge of objects develops with experience. It is known, for example, that infants’ perceptual sensitivity to the property of objects causally influencing one another emerges later than perceptual sensitivity to the property of continuing to exist when unperceived. This can be explained in Bermudez’s theory, as neural networks become increasingly more efficient in making a wider range of predictions, as it is exposed to objects interacting with one another in various ways. As he puts it, human infant's perceptual development should be understood in terms of perceptual sensitivity to an increasing range of object properties” Bermudez : , which emerges at more or less constant stages in human ontogeny. But in addition to being sensitive to more canonical object properties, we also learn to be sensitive to the same properties under different modes of presentation. It is known, for example, that sensitivity to the property of being subject to gravity or of falling when unsupported is not an all-or-nothing matter, but gradually develops in order to encompass different circumstances. At months of age infants show surprise only to the event depicted in the top display of figure below, but not to the others. But their sensitivity to this proper-

 0aturally, we should also expect anticipatory saccades to be made in the direction of the anticipated movements in each case. I am not sure if these predictions have been tested yet.

Bermudez’s object properties model of object perception | 233

ty gradually develops in time, as they learn to recognize it in different circumstances (as shown in the other events depicted in the figure).

Fig. 30: Violations of expectations concerning support relations in young infancy (from Baillargeon 1999)

Moreover, as the relevant neural connections are strengthened these representations become strong enough not only to guide looking behaviour, but also to drive motor outputs as well. It is known that although infants already have expectations concerning object permanence at around 4 months of age, they do not actively search for occluded objects until much later, at about 7 – 8 months of age. This décalage can also be explained in Munakata’s model. In another simulation with neural networks, Munakata et al. have used the same input as that illustrated in figure 29 (page 231) with a network exhibiting the same representational system as before, but with an extra possible output. In addiction to the prediction output, they have included an overt reaching response as well. Based only on the network’s ability to sustain an object representation during occlusion – and so still in the domain of perceptual sensitivity – the authors have shown how the relevant object representations may be strong enough to make accurate predictions, but still too weak to drive reaching responses (as is

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 The Pragmatic View of Demonstrative Thought II : Object Representation

the case with month-olds . With learning, however, the representation is strengthened to a point where it becomes sufficiently strong to drive the kind of reaching responses that is observed in – month-olds. As the authors put it: Development of the representational system improves network performance by strengthening the representations of occluded objects so that longer delay periods can be withstood and the relative weakness of the reaching system can be overcome. This representational development may be sufficient to allow a system that could initially reach only for visible objects to then reach for occluded objects as well. In this way, representational developments may be critical to infants’ increasing abilities to demonstrate sensitivity to hidden objects across a range of tasks. Munakata et al. :

0ow, there is nothing in this model that I disagree with. In fact, it is fully compatible with the way practical knowledge develops according to the theory advanced in chapter six. When it comes to explaining what it is for one to be perceptually sensitive to these canonical object properties, Bermudez’s theory and Munakata’s networks offer a powerful framework which accounts very well for infants’ intelligent and purposeful behaviour towards objects, manifested in prediction experiments and eventual motor interactions. But as our goal in this book is to answer the conceptualist challenge and explain how a stronger understanding of object permanence may be possible, Bermudez’s model does not take us far enough. It is successfully able to explain sensorimotor knowledge and perceptual sensitivity, but we need more than that: we need to show how one can have a practical knowledge of object’s persistence that extrapolates to non-perceptual contexts, allowing one to understand that the object continues to exist regardless of one’s current perceptual interactions with it. Bermudez’s account of practical knowledge, structured in terms of perceptual predictions and reaching movements, cannot help us here. So having in mind the theory of practical knowledge advanced in chapter six, this is what I propose: the cases that Bermudez’s theory explains in terms of perceptual sensitivity mark the beginnings of object representation. In the present terminology, these would correspond to case of the spatial scenario I have used to introduce the cognitive space: the case where the organism can only reach the goal within a very limited zone of competence, restricted to locations from which the goal is visible see page . But as our practical knowledge of objects improves we become sensitive to these properties in a wider range of circumstances, and under different modes of presentation. This endows our practical knowledge with an increasingly higher degree of portability and objectivity, to a point where we can extrapolate our knowledge to nonperceptual contexts in order to understand that the object we have interacted

The graded knowledge approach: beyond perceptual sensitivity 

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with will continue to exist unperceived. As we shall see in the next section of this chapter, this may be fully explained within the domain of practical knowledge, without having to appeal to more sophisticated forms of conceptual knowledge.

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The graded knowledge approach: beyond perceptual sensitivity

In the previous section I have introduced the graded knowledge approach developed by Yuko Munakata and collaborators, which provides a neurobiological basis of our practical knowledge of objects. The basic idea behind the graded knowledge approach can be captured in the following passage from Munakata and Yerys: Within [the graded knowledge approach] knowledge is viewed as emerging from, and embedded within, the interaction of multiple endogenous and environmental components including the details of motor systems, as emphasized by dynamic systems account . As a result, knowledge can be graded in nature, with underlying representations varying in strength with the degree of support from multiple interacting components. … 0o single measure is viewed as revealing full knowledge, and measures that reveal limitations are not explained away in terms of deficits solely in other systems. Instead, a range of behaviors is viewed as revealing some degree of knowledge, with the strength of underlying representations contributing to dissociations observed across measures. Munakata & Yerys :

This framework was successfully employed by Bermudez in characterizing what it is for one to be perceptually sensitive to canonical object properties, but it should be mentioned that the graded knowledge approach is not limited to these more primitive forms of knowledge. It has also been successfully applied to a wide range of topics in cognitive development, control and flexibility, such as rule representation and strategical behaviour Wendelken et al. , executive control Munakata et al. , linguistic recall Snyder et al. , dissociations between declarative knowledge and action i.e., being able to articulate one’s knowledge while simultaneously failing to act in accordance to it – Munakata & Yerys , perseverance behaviour i.e., repeating prior behaviours that are no longer adequate – Munakata , etc. More directly relevant to our case, the graded knowledge approach also seeks to understand how object knowledge develops beyond the basic cases of perceptual anticipations, when we become able to sustain a representation of an unperceived object as if it were perceptually present. That is to say, in terms

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 The Pragmatic View of Demonstrative Thought II : Object Representation

of a representation that is sufficiently strong to support our knowledge of objects even when unperceived. As this knowledge is graded, developing gradually as the relevant neural connections are strengthened as a function of experience, this fits perfectly with the theory of practical knowledge advanced in chapter six. In this section of the chapter I will then explain how object representations develop beyond perceptual sensitivity, which will form the basis for ‘the pragmatic view of demonstrative thought’. We can begin our discussion by asking: what it would be for one to understand that an object persists in time, in a way that extrapolates to nonperceptual contexts? Let’s begin with the perceptual case discussed above. In accordance with the graded knowledge approach, infants’ practical knowledge that objects continue to exist unperceived is graded, capable of being manifested in some tasks but not in others. Looking-time measurements and eyetracking recordings may reveal sensitivity to object permanence in montholds, while at the same stage of cognitive development they may fail to exhibit this sensitivity if measured by manual search tasks. As we’ve also seen above, this décalage fits very well with the predictions of the graded knowledge approach. Some tasks require stronger representations than others, and as the neural connections that represent objects strengthen gradually as a function of experience, at any given point in cognitive development a representation may be strong enough for some tasks but not for others. But as I have been insisting throughout this dissertation, there need not be a precise point where one is then credited with the understanding that objects continue to exist when unperceived. Rather, what we have are stronger and weaker object representations, which allows one to manifest this understanding in some contexts but not in others. At first, these contexts are restricted to our perceptual tracking of objects as they become temporarily occluded behind obstacles, exhausted in our expectations that an object will soon come into view again at the other side of the occluder or in our sensorimotor knowledge of where to reach in order to physically manipulate it. But as this representation gradually strengthens and benefits from the development of other brain structures – more specifically, structures in the prefrontal cortex P)C – we become able to actively maintain this representation in a way that is increasingly less dependent on perceptual input and perceptual expectations. This endows our practical knowledge of objects with a higher degree of portability and objectivity, which extrapolates to nonperceptual contexts. We can make this idea clearer by looking at the development of infants’ capacity to represent hidden objects. One interesting prediction of the graded

The graded knowledge approach: beyond perceptual sensitivity 

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knowledge approach is that if longer exposure to an object strengthens its neural representation, then we should expect that representations of familiar objects should be stronger than representations of new objects. This difference, in turn, should be reflected in infants’ performances on reaching tasks: if reaching for hidden objects require stronger representations, then the prediction would be that infants start out with a reaching preference for familiar objects, which extends to novel objects only at a later stage in cognitive development. This is somewhat surprising, given that a general preference for novelty confers greater adaptive advantage to an immature cognitive system such as the young infant’s, as an effective strategy to acquire larger amounts of information in a relatively short period of time. But if strong neural representations are required to drive manual search towards hidden objects, then the prediction is that if both a novel and a familiar object are hidden from view, infants should search more often for the familiar one. Conversely, if weaker representations suffice to guide manual reach for visible objects, if the infant is simultaneously presented with a familiar and a novel object in full view their reaching preferences should be reversed. This is exactly what Shinskey and Munakata have found . In one type of experiment, month-old infants were successively presented with a random object a coloured block of a certain shape, to control for complexity , until they’ve become sufficiently familiarized with it i.e., until they’ve lost interest and ceased their attempts to reach for it . If the experimenter then presented infants with both the familiar and a novel object in full view, they showed systematic preferences for the novel one. However, when both objects were hidden from view by turning off the lights in the room, infants reverse their preferences, reaching more often for the familiar object Shinskey & Munakata , Shinskey . This is consistent with the graded knowledge approach, and can be explained by the strength of the underlying object representations. Reaching behaviour for visible objects require only weak representations, so the general preference for novelty can be maintained even if the representation of the novel object is still weak. Search behaviour for hidden objects, on the other

 That infants exhibit a general preference for novelty has been demonstrated in numerous empirical studies, reviewed in Shinskey & Munakata . But it should be noted that there are important exceptions to this general preference: infants may prefer familiar stimuli if they’ve had insufficient or interrupted familiarization, or if the familiar stimulus is significantly more complex than the novel one Houston-Price & 0akai , Streri & )erón . As the experiments reviewed in this section control for these kinds of situations, I shall ignore these exceptions in the discussion that follows.

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 The Pragmatic View of Demonstrative Thought II : Object Representation

hand, require stronger neural representations, which have only been attained with objects the infant has become familiarized with. This explains why infants reverse their reaching preferences with respect to objects concealed by darkness. One important lesson to be drawn from these observations is that the ability to represent the continued existence of an object has its origins in our learning from specific experiences and interactions with objects that have become familiar to us. As we become familiarized with the objects we most often interact with, their respective neural representations strengthen, allowing us to actively maintain them in working memory even when they are temporarily hidden from view. These capacities mark the beginnings of our understanding of object persistence, but we still haven’t moved beyond the level of causal indexicality. Our understanding of object persistence at this point remains highly dependent on our idiosyncratic history with objects, and is exhausted in our perceptual anticipations and sensorimotor knowledge. But interestingly, at some point in cognitive development these preferences reverse again. After testing month-olds’ search preferences towards hidden objects, Shinskey & Munakata tested month-olds in the exact same experimental setting, and have found that when a familiar and a novel object are simultaneously hidden by turning off the lights, infants search for novel objects more often than familiar ones. In this case, infants reaching preferences with hidden objects have come to resemble those with visible objects, where weaker representations suffice to guide manual reach. The infant has acquired a more general capacity, to represent a novel hidden object like a visible one, to maintain a weaker representation active in working memory until more information about the object can be obtained. Of course, a more rudimentary form of this capacity was already present in month-olds, but in a way that was still constrained by the infant’s own idiosyncratic history with the object. But at months of age the infant becomes able to generalize from her specific experiences with familiar objects to novel ones, manifesting a practical knowledge that if a newly found object is suddenly hidden, it will continue to exist unperceived. This generalization ability, as we shall see in the next section, relies on processing in the prefrontal cortex P)C , which encodes information in a more abstract manner that abstracts away from idiosyncratic details of particular stimuli. In effect, what I will suggest is that P)C representations constitute a  With some minor differences in exposure time and distance to object, to compensate for infants’ more developed sensorimotor capacities see Shinskey & Munakata for details .

0atural stabilization and the prefrontal cortex 

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form of ‘natural stabilization’, creating superordinate representational categories like ‘object’ that are more easily generalizable from one circumstance to the next. This will play a crucial role in explaining how our understanding of object’s continued existence may improve as a function of experience, and be endowed with a higher degree of portability and objectivity.

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0atural stabilization and the prefrontal cortex

We rarely experience two situations that are alike in every single respect, and yet we are remarkably good in adapting ourselves and learning how to behave appropriately in novel situations we haven’t experienced before. This cognitive flexibility has been shown to rely heavily on the prefrontal cortex P)C , a collection of interconnected neocortical areas that sends and receives projections from virtually all cortical sensory systems, motor systems and subcortical structures. The P)C has also been linked to analogical reasoning, working memory, cognitive control, decision-making and problem solving. Kharitonova and Munakata , for example, have shown that perseverance behaviour in taskswitching i.e., failure to modify one’s past behaviour in light of the novel task is linked to task-relevant information being represented in posterior cortical areas, which has been independently shown to encode information in a more detailed and stimulus-specific manner. More flexible switching and adaptation, in contrast, is linked to task-relevant information being actively sustained via neuronal firings in the prefrontal cortex, allowing it to be maintained in working memory as one switches flexibly from one task to another. This is because prefrontal representations have been shown to encode information in a more abstract format, collapsing across specific idiosyncratic details and forming more abstract superordinate representational categories, which allow them to be more easily applied outside the learning context. This, I suggest, is a form of ‘natural stabilization’, whereby certain features of the world are stabilized together in these superordinate categories, ‘object’ being one of them. But what exactly is the role of the prefrontal cortex in natural stabilization? We can make this idea clearer with 0icolas Rougier and collaborators’ work on connectionist models of P)C processing . Their work seeks to demonstrate that the interaction of P)C-specific neural mechanisms with a wide scope of  See Miller & Cohen for further anatomical details. Speed , Ashby & Ennis , O’Reilly & )rank . Miller & Desimone , Jog et al. .

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 The Pragmatic View of Demonstrative Thought II : Object Representation

task experiences is sufficient for abstract higher-order representations to emerge in the P)C, leading to higher cognitive flexibility. In order to construe this model, the authors start out with the empirically well-supported assumption that the prefrontal cortex has three distinctive capacities: . Active maintenance of patterns of neural activity over time, protecting it against interference from competing inputs so that task-relevant information may be efficiently held in working memory based on recurrent excitatory activity in the P)C . . Adaptive updating of P)C activity patterns, by dynamically switching between active maintenance and rapid updating of new representations based on gating mechanisms linked to the basal ganglia and midbrain dopaminergic circuitries . . Modulation of processing in other cortical areas responsible for task execution for example, the posterior and sensory cortices , based on intensive interconnectivity between these areas. These capacities are incorporated into the model through different interconnected neural structures, and the full network is then tested on its ability to generalize its behaviour across different tasks involving novel stimuli. The authors’ hypothesis is that the activation of these neurobiological mechanisms in different task experiences is sufficient for the P)C to self-organize into more abstract representations, allowing the network to make more successful generalizations to novel circumstances. The stimuli presented to the network varied along a number of dimensions shape, size, colour and spatial location , and the network was tested in either two or all of the following tasks: name a feature a particular colour or shape , match a feature indicate whether two stimuli have the same size, colour or shape , smaller feature or larger feature indicate which one of two stimuli is smaller or larger . The task switched after every block of trials, while the relevant dimension was switched after two full task cycles. To test for generalization, the network was exposed only to a subset of feature values along every dimension at a given task only about % of all possible combinations of features . Generalization was then measured by the network’s ability to respond to stimuli it had not seen before in a given task. The authors tested networks of varying complexity and under different conditions: with all or a

 See Rougier et al. for further physiological details, as well as references to the empirical studies that support them.

0atural stabilization and the prefrontal cortex 

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subset of the P)C-specific neural mechanisms, and with training in two or all of the four possible tasks. Interestingly, what they found is that only the full P)C model, encompassing all SPC-specific mechanisms and capacities, developed synaptic weights and patterns of activity that encoded more abstract representations of dimensions of features ‘colour’, ‘shape’, etc , which encompass various features within any given dimension Rougier et al. : . These representations aided task performance by being actively maintained in the P)C while sending topdown excitatory support for the relevant stimulus dimension. )or example, if the task at hand was to name a particular colour, the more abstract representation of the ‘colour’ dimension would be actively maintained in the P)C, and would constantly send excitatory signals to sensory representations of particular colours for the whole duration of the task. The adaptive gating mechanism, in turn, learned to update P)C activity whenever the relevant dimension to the task at hand switched. If the task changes from naming colours to naming shapes, a more abstract representation of the ‘shape’ dimension would be actively maintained, and excitatory signals sent to the sensory and posterior cortices. Due to the more abstract nature of these representations, we should also expect that they would be able to modulate not only processing of familiar stimuli i.e., those in which the network was trained but also processing of novel stimuli – that is to say, we should expect the full P)C network to be able to generalize from its prior experience to novel situations, which is exactly what was observed. The full P)C network exhibited significant generalization capacities, achieving % accuracy on stimulus for which it had no prior same-task experience Rougier et al. : . In contrast, if one or more of the P)Cspecific components was shut down, the network’s generalization capacities were severely compromised. This fits very well with empirical data on patients with P)C damage tested in card sorting tasks, who exhibit perseverance behaviour and fail to adapt when the sorting task changes ibid. . In addition, significant generalization was observed only in networks that received training in all four tasks: those that trained in only two of the tasks showed reduced generalization capacities, making four times as many errors ibid. . This shows that cognitive flexibility and generalization arise not only from a fully operational P)C but also as a function of the range of experiences we have in the world. As we actively engage with our external environment in a variety of different tasks, we bring to the foreground of our experience now one dimension of the environment, now another; on this basis, P)C-specific neurobiological mechanisms are able to stabilize certain features of the environment

   The Pragmatic View of Demonstrative Thought II : Object Representation into more abstract superordinate dimensions, which endows the cognitive system with greater cognitive flexibility and adaptability to novel situations. These P)C representations are the result of what I have been calling ‘natural stabilizations’. The superordinate category abstracted from experience emerges naturally as a dynamic property of the system, arising when P)C-specific neural mechanisms combine with a wide breadth of sensorimotor engagements with the world. It is only implicitly encoded in the form of patterns of neural connectivity in the P)C, and deployed in experience in the manner suggested above: through interconnectivity with the posterior and sensory cortices mediated by the adaptive gating mechanism. Here’s a more detailed account of how these representations may emerge, in a cognitive system with the relevant neurobiological structures and which actively engages with is environment in a variety of ways: There is a clear mechanistic explanation for why the combination of rapid updating and sustained active maintenance of task rule representations in the full P)C model which depends on the adaptive gating mechanism was critical for the formation of abstract … representations during training. Within a block of trials with the same relevant dimension, the specific features within that dimension varied, but a constant P)C activity pattern was maintained due to the gating mechanism. This caused these P)C representations, which initially had random connections, to begin to encode all of the varying features within a dimension, resulting in an abstract dimensional representation. In contrast, other networks [i.e., those with only a subset of P)C-specific mechanisms] tended to activate new representations for each new stimulus as the specific features changed and thus were unable to form the dimensional abstraction across features. Rougier et al. :

And what I now want to suggest is that ‘object’ is precisely one of these categories: an abstract, superordinate P)C representation that gradually emerges as canonical object properties are naturally stabilized as a function of our active engagements with objects in the world. To make this point clearer, let’s return to the case where infants at months of age become able to reach for novel objects even when these are temporarily hidden from view. As we’ve seen above, this sensorimotor capacity requires infants to be able to represent an unperceived object like a visible one, i.e., to actively maintain the representation of the hidden object in working memory until more information can be obtained Shinskey & Munakata / . This is a more general capacity than that exhibited by month-olds, who are only able to reach for hidden objects that are already familiar to them. In order to support this ability, certain features of objects – namely, a number of their canonical properties – become naturally stabilized and represented

0atural stabilization and the prefrontal cortex 

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in the prefrontal cortex as the more abstract superordinate category ‘object’. This representation emerges gradually in the P)C, as a result of a wide range of experiences in the world being combined with P)C-specific neurobiological structures. As we actively engage with objects in various ways, we bring some of their canonical properties to the forefront of our experience, depending on the task at hand: Baillargeon’s support experiments see fig. , p. highlight the property of being subject to gravity, while Kotovsky and Baillargeon’s scenarios of physical contact fig. , p. highlight other properties having mass, exerting and being subject to force, causally influencing other bodies, etc . Just like the network in Rougier’s experiments has learned to extract a more abstract dimension of ‘colour’ from a series of interactions with particular colours, the more abstract category ‘object’ is extracted from repeated patterns of interactions with particular objects, as they manifest different canonical object properties. With the support of P)C-specific neurobiological mechanisms, these properties are naturally stabilized together in order to form a more abstract representation in the P)C – ‘object’ – which abstracts away from the particular ways in which these properties are manifested in experience. So if one is engaged in a task that highlights the property of being subject to gravity, and then shifts to a context where the property of causally influencing other bodies is highlighted, a more abstract representation of ‘object’ will be activated in the P)C, sending excitatory signals to the posterior and sensory cortices and guiding our active interactions with the object in each case. Its more abstract nature also allows us to generalize from our prior experience to novel encounters, as the P)C representation activates whenever we are faced with what seems to behave like an object. This representation, as we’ve seen, may be actively maintained in working memory even if the object cannot be perceived, allowing us to represent the continued existence of the object. These capacities, I suggest, corresponds to our practical knowledge that objects persist in time. In conformance with the present theory this knowledge is graded, and may be manifested in some contexts but not in others. At first, it is manifested only in our perceptual expectations concerning the reappearance of occluded objects at the other end of their occluders, or in longer looking times at events that violate our perceptual expectations. But we have also seen how this knowledge may develop so as to encompass a wider range of circumstances, being manifested in our attempts to reach for familiar objects that have been hidden, and eventually in search behaviour towards hidden novel objects as well. This development of our practical knowledge is mediated by the prefrontal cortex, where a more abstract representation emerges that stabilizes certain features that are common to the objects we routinely interact with. This P)C

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 The Pragmatic View of Demonstrative Thought II : Object Representation

representation may be maintained in working memory even in the absence of perceptual input, and generalizes to novel experiences with unfamiliar objects. What this suggests is that the cognitive flexibility and adaptability afforded by the P)C is partially responsible for endowing our practical knowledge with a higher degree of portability and objectivity. But as I have been insisting throughout this chapter, this ‘object’ representation is only implicitly encoded in patterns of activation in the P)C as it interacts with other cortical and subcortical structures. As Rougier et al. have shown, the operations of P)C-specific neurobiological mechanisms, in combination with a wide range of experiences in the world suffices for these more abstract representations to emerge. We are not required to appeal to more sophisticated forms of conceptual knowledge in order to account for flexible and adaptive cognitive behaviour towards objects. In the next section of the chapter I will then put these observations in the context of the theory of practical knowledge defended in chapter six. We will then be in a position to see how the conceptualist challenge can be met, and how our practical knowledge of what objects are and how they behave, supported by abstract P)C representations, can be extrapolated to non-perceptual contexts as well. This will be sufficient to distinguish individual objects from instances of property-kinds, without having to appeal to conceptual knowledge or to our capacity to adopt a more detached and disengaged perspective upon the world.

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A pragmatist answer to the conceptualist challenge

In order to see how practical knowledge of objects may account for our capacity for singular representation, let us remember the three spatial scenarios from Cussins , which I have used to introduce the cognitive space in chapter six:

Case : Limited zone of competence within a certain space from Cussins 99

A pragmatist answer to the conceptualist challenge 

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At one end of the cognitive spectrum we have ‘case ’, where the organism’s zone of competence relative to a goal G is very limited, restricted to cases where G happens to be visible from the organism’s point of view. In the cognitive space of ‘object’, this would correspond to the practical knowledge Bermudez describes in terms of ‘perceptual sensitivity’ to canonical object properties, exhausted in our anticipations and expectations as we perceptually track an object in space. This zone of competence may be slightly expanded as we learn to be perceptually sensitive to more object properties under different modes of presentation, but it is still restricted to cases where the object is visible or hidden for short durations of time. At the other end of the cognitive spectrum we have ‘case ’, where the zone of competence is expanded so as to cover the entire territory. In this case, there are no privileged positions within the space where one must be located in order to reach the goal in an intelligent and purposeful manner. In the cognitive space of ‘object’, this would correspond to what Evans described as a ‘fundamental identification’ of an object. As we’ve seen in chapter five section . , a fundamental identification of an object identifies it by its unique position in a unified, objective spatiotemporal framework, where it is uniquely and simultaneously related to every other element in the framework. In this case, the object is not identified solely by its contingent relation to the subject: it can be identified by its simultaneous relations to other elements in the framework as well.

Case : Maximal zone of competence within a certain space from Cussins 99

The conceptualist tells us that singular representation is only possible in case . Much of the conceptualist argumentation, as we’ve seen, comes from contrasting this case with the more primitive sensorimotor capacities manifested in case , which do not warrant ascriptions of singular content. But as I have repeatedly argued throughout this dissertation, this simple dichotomy is too

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 The Pragmatic View of Demonstrative Thought II : Object Representation

rough. We can account for our capacity for singular representation at the more intermediate ‘case ’, which moves beyond the simple sensorimotor capacities of case while still falling short of the conceptual knowledge emphasized in case . Cases of type are those where we expand our zone of competence by learning to stabilize various features of the environment in the form of landmarks , which we can use in order to reach the goal even when it is not visible from our point of view.

Case : Intermediary zone of competence within a certain space from Cussins 99

In the cognitive space of ‘object’, what this means is that certain properties of objects become naturally stabilized in the form of a more abstract, superordinate representation in the prefrontal cortex. This representation constitutes a type of metaphorical landmark, which we can use in order to represent the object from different perspectives and for increasingly longer periods of time, even in the absence of perceptual input. On this basis, we can have a practical knowledge that objects persist in time and continue to exist when unperceived, which develops beyond the more primitive perceptual knowledge depicted in case . In accordance with the present theory this practical knowledge is graded, and may be manifested in some contexts but not in others. In a more basic case of type- , our practical knowledge is manifested only in our sensorimotor capacities to reach for hidden objects in the dark or behind occluders. But as our ability to actively maintain the object’s representation is developed supported

 Interestingly, these capacities also come in degrees; infants begin searching for objects hidden by covers later than they search for objects hidden in the dark Shinskey & Munakata .

A pragmatist answer to the conceptualist challenge 

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by the developing prefrontal cortex we become able to represent the continued existence of the object for increasingly longer periods of time, even in the absence of perceptual input. On the basis of this capacity, and in combination with our practical knowledge that objects move in an independent manner, we can learn to represent the continued existence of an object as it moves through space, which we can extrapolate to non-perceptual contexts as well. Instances of this capacity have been observed in several delayed matching to sample tasks, where subjects need to actively sustain an object representation in mind in order to match it to a target object that appears after a certain time, during which the object is not perceived. What these studies show is that cells in the P)C that represent the target object show heightened activity during the delay period, which is taken to be the neural correlate of the capacity to represent the continued existence of the object during longer periods of nonobservation. At the same time that activity in the P)C is enhanced, activity in sensorimotor areas that represent more specific surface properties of the object is diminished during the delay period Courtney et al. . During periods in which the object is not currently perceived the sensory representation of the target object will weaken or disappears altogether, but the more abstract P)C representation will allow us to represent the object's continued existence across perceptual and non-perceptual contexts. These effects, as Rainer and Miller argue, aren't due to attentional modulation but to what they call 'experience-based modulation'; that is to say, through our experiences with objects selective strengthening occurs between neurons in the P)C and neurons in the visual system that represent the object in question. This allows the representation to be actively maintained through heightened activity in the P)C even in the absence of perceptual input, for increasingly longer periods of non-observation Rainer & Miller . Interestingly, it has also been found that subjects are better with delayed matching to sample tasks concerning familiar objects relative to novel ones. This is specially true when the object shown after the delay period is degraded relative to the initial target object Rainer & Ranganath . At the neural level, it's been observed that familiar objects elicit less overall neural activity in the P)C relative to novel ones, but that neurons are more narrowly tuned to represented objects that are more familiar to the subject. This makes the representation more resistant to the effects of degradation, supporting a more accu-

 Miller et al.

, Warden & Miller

.

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 The Pragmatic View of Demonstrative Thought II : Object Representation

rate matching. Its more abstract nature also makes it less dependent on specific surface properties, thus explaining subjects' better performance on delayed matching to sample tasks. The fact that these effects are better observed with familiar objects relative to novel ones fits well with data from Rougier et al. reviewed above, where a wide range of experiences was required for these more abstract representations to emerge in the P)C. As familiar objects are those which the subject has had more experience with, this explains why their representations survive better the effects of degradation after a period of non-observation. Even as the context changes, the representation is less dependent on actual perceptual input and may be actively held across perceptual and non-perceptual contexts. )or example, as we experience a familiar object travel away from us and return in regular patterns, or as we travel away from the object and return at a later time, we can exploit our capacity to keep the object’s representation active in the P)C in order to understand that it is the same object that travelled away from us and now returns or that it is the same object which we have left behind and now encounter again , and which continues to exist during its or our travels. A child who has seen its Christmas present be placed under the tree on Christmas Eve can actively maintain its representation all through the night, as she lies awake anxiously waiting for Christmas morning. When she returns after a sleepless night she understands that she is faced with the same object left under the tree the previous night, which she kept in mind the whole time she lay awake in the dark. In a similar vein, when the bird that has nested in my chimney leaves its nest in order to find food, I can maintain its representation active in the P)C until it returns, and on this basis understands that it is the same bird that has travelled away from its nest and now returns. And even when the object does not eventually return, we can still deploy our practical knowledge of objects’ capacity for independent movement in order to know that this object continues to exist away from us we may still hope for its return, for example . Differently from the conceptualist who seeks to explain this understanding through a so-called ‘objective’ conception of space, my suggestion is that we can attain this understanding by gradual extrapolation of our practical knowledge of properties like persistence and independent movement. This is yet another expansion of our zone of competence in the cognitive space of ‘object’, one that is fundamental for the theoretical project of distinguishing individual objects from instances of property-kinds. Granted, our capacities for temporal and spatial representation at this level may not be sufficiently developed to support the whole range of property attributions that Evans’ fundamental identification of objects supports. But these capacities, I

A pragmatist answer to the conceptualist challenge 

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maintain, suffice to distinguish individual objects from instances of propertykinds as the representata of our mental states. )or as we’ve seen in chapter five, representations of the property kind ‘spatiotemporally coherent segregated spatial structure’ are construed on the basis on pre-attentive segregation processes and attentional selection, fading away shortly after the perceptual encounter has come to an end Hatfield . )lexible P)C representations, in contrast, may be actively maintained for longer periods of time, allowing us to understand that a familiar object that travels away from us continues to exist as it moves in an independent manner. Of course, this understanding is fallible, as it is possible for the object to be replaced by a qualitatively identical one at some point during its travels. In this case, if the object returns our reidentification of it as the same one we have perceived earlier and which we have kept in mind will turn out to be mistaken. But there’s nothing wrong with this scenario: developing further ways to check for sameness of numerical identity after a period of interrupted observation is precisely one of the ways in which we expect our practical knowledge of objects. Our being able to draw a distinction between numerical and qualitative identity, which the conceptualist often emphasizes as a requirement on singular representation, is itself a gradual matter, which may be manifested in some contexts but not in others. So when Bermudez, for example, says that to perceive a particular object like a particular tree as a particular is to perceive it as an individual thing, as something that persists over time and can be encountered at different times and in different sensory modalities. It is to be able to reidentify the tree; to be able to pose the question, for example, whether the tree in front of one is the same tree perceived earlier; or to be able to select one tree out from a group of perceptually similar trees; or to be able to count the number of trees in one’s immediate vicinity” Bermudez : – we don’t have to understand this as conjunction of conditions as most conceptualists do which must all be in place if singular representation is to be possible. In the spirit of the pragmatic view, these are all different manifestations of our practical knowledge of objects, which develop gradually in the manner suggested here. Some of these capacities, for example ‘to be able to select one tree out from a group of perceptually similar trees’ require only some very rudimentary sensorimotor capacities, while others like ‘being able to pose the question whether the tree in front of one is the same tree perceived earlier’ rely on more sophisticated forms of understanding. But there need not be a precise point where one becomes able to draw a distinction between qualitative and numerical identity, thus making singular representation possible. The capacity to apprehend one’s external environment as structured

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 The Pragmatic View of Demonstrative Thought II : Object Representation

into individuals is graded, developing as our practical knowledge of objects is endowed with a higher degree of portability and objectivity. This, in short, is the ‘pragmatic view’: a pragmatist approach to the study of demonstrative thought which seeks to explain it in terms of our practical knowledge of what objects are and how they behave, which is endowed with a higher degree of portability and objectivity as we actively interact with objects in the world. These interactions, in combination with P)C-specific neurobiological mechanisms, give rise to a more abstract representation that stabilizes certain features of objects, affording us a more general and flexible understanding of what objects are and how they behave. This understanding, as I have been arguing, is practical in nature, being supported by abstract ‘object’ representations implicitly encoded in the P)C and developed along a number of dimensions as a function of experience. This practical knowledge – or, to put in the present terminology, the capacity to move in the cognitive space of ‘object’ with the use of various ‘landmarks’ i.e., abstract ‘object’ representations – allows us to differentiate between individual objects and instances of property-kinds, without having to appeal to more sophisticated forms of conceptual knowledge. And when we become able to represent individual objects in this manner, we are then in a position to have demonstrative thoughts about them, or to engage in object-directed mental activities with singular demonstrative contents. Our practical knowledge of objects accounts for the singular element of this content, while the demonstrative element may be explained in the manner suggested by the perceptualist: that is to say, by segmentation processes that parse the visual array into perceptual elements proto-objects , attentional processes that endow protoobject representations with greater spatiotemporal coherence, and sensorimotor knowledge that gives the object spatial significance. But before we conclude our investigation, there’s a further complication we must address. )or although we have seen in some detail how features may become naturally stabilized in abstract ‘object’ representations, we haven’t yet seen how they may become de-stabilized. But as according to the present theory a capacity for de-stabilization is crucial in endowing our practical knowledge with a higher degree of portability and objectivity, we must say something about ‘natural de-stabilization’ as well. This will be the main subject matter of the next subsection of this chapter.

0atural de-stabilization 

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0atural de-stabilization

According to the theory of practical knowledge advanced in chapter six, our practical knowledge of objects can be understood as the capacity to move in the cognitive space of ‘object’ in an intelligent and purposeful manner, within a certain zone of competence. This encompasses a number of different but interconnected abilities, namely: . To have dispositions to deploy our practical knowledge of objects successfully in each circumstance of the dispositional set; . To be able to recognize other circumstances in the zone of competence as circumstances where it would be appropriate to deploy our practical knowledge of objects; . To be able to expand the zone of competence by adding novel circumstances to the dispositional set; . To be able to recognize the boundaries of the zone of competence, i.e. circumstances where it would not be appropriate to deploy our practical knowledge of objects; . To stabilize certain features of objects under a more abstract ‘object’ representation; . To be sensitive to circumstances in which we are required to destabilize features and re-stabilize them again. Throughout this chapter we have already seen various ways in which abilities – may be manifested and improved. But we have said little about ability , which is also crucial to our practical knowledge of objects. At the same time that the capacity to stabilize object features in a more abstract P)C representation is essential to have a more flexible and general knowledge of objects, I have also argued in chapter six that stabilization is not the only factor responsible for endowing our practical knowledge with a higher degree of portability and objectivity. Part of what it is to have a more flexible understanding of objects also involves being sensitive to circumstances in which the previously stabilized features need to be de-stabilized, in order to yield more accurate and reliable predictions of how objects behave as we actively engage with them. )or example, we have already mentioned before that some objects will not have certain canonical object properties. Objects that are lighter than air like helium balloons are not subject to gravity in an interesting sense, while others like birds are capable of overcoming the effects of gravity. )urther on, while most objects do not change shape in dramatic ways, some do: the Brazilian three-banded armadillo for once is capable of curling up into an almost perfect

   The Pragmatic View of Demonstrative Thought II : Object Representation sphere. To illustrate with an example, if in our first perceptual encounter with a bird we represent it with a more abstract ‘object’ representation, we will naturally expect it to fall if its support is suddenly removed. These expectations, however, will be violated when we observe that upon removal of its support the thing actually moves up rather than downwards. The more abstract ‘object’ representation has yielded a false prediction, and we soon learn that our general knowledge of objects cannot be applied indiscriminately across the board: not everything that has mass, exerts and is subject to force etc., will also fall when unsupported. At this point, our ‘object’ representation needs to be reopened and its features de-stabilized, until we learn which features may be appropriately re-stabilized again. This process of de-stabilizing features and re-stabilizing them again is also accomplished by P)C structures. More specifically, by dopaminergic circuitry in the striatum, connected to the P)C through the adaptive gating mechanism described by Rougier et al. above. These mechanisms constitute a form of ‘natural de-stabilization’, which complement our practical knowledge of objects and endows it with a higher degree of portability and objectivity. This is how natural de-stabilization works: as we’ve seen, ‘object’ representations in the P)C encode more abstract features of objects, developing a preferential response to these features on the basis of our experience and active engagements with them. There is strong empirical evidence that dopaminergic striatal circuitries play a key role in this stabilization process, by acting in the following manner: whenever the more abstract representation yields successful predictions concerning objects’ behaviours – for example, when we deploy in order to predict that an unsupported object will fall, and the object does fall – there is a spike in dopamine release in the striatum, which strengthens the connections between the representation and the property in question. 16 But as Ann Speed emphasizes, how persistent this representation will be – by which she means, how long it will be stored in long-term memory stabilized in this manner if it is stored in long-term memory at all – depends on its predictive power, as a function of the environmental feedback it receives. That is to say, if a certain predicted event like the object’s fall fails to hold, dopamine levels in the striatum drop, ‘unclamping’ P)C neurons that respond preferentially to this more abstract property. This ‘unclamping’ allows neurons to stop responding preferentially to the property that is no longer applicable, leaving

 )or the relevant empirical evidence see Speed O’Reilly & )rank .

, )rank

, Ashby & Ennis

and

0atural de-stabilization 

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them ‘free’, as it were, to develop preferential responses to other features that may yield more successful predictions. This process of ‘unclamping’ neurons in the P)C, effected by dopaminergic circuitries in the striatum, is what I have been referring to as ‘natural destabilization’: as Ashby and Ennis put it , dopaminergic signals have the functional role of a teaching signal for the brain, as they indicate when features need to de-stabilized and re-stabilized again in a different manner. This fits very well with empirical evidence that damage to these circuits leads to perseverance behaviour and deficit in category learning. Once features have been de-stabilized in this manner, it is likely that there will be a period if instability, as it will not be clear which features should be stabilized so as to yield successful predictions concerning the odd object’s behaviour. Is it the case that all things with the same shape as ‘this object’ the bird will not fall when unsupported? A tentative re-stabilization might occur at this point, but due to its limited predictive power, the lack of environmental feedback will result in low levels of dopamine and cause another destabilization. After all, objects with other shapes like helium balloons do not fall if left unsupported, and objects with similar shapes like a statue of a bird will fall when unsupported. But as we continue to be exposed to, and actively interact with, an increasing number of things that do not fall when unsupported, we may learn, through the processes described here, which features are more likely to yield successful predictions. These features may then become restabilized as a different type of abstract representation, as neurons in the P)C develop preferential responses to them: not just ‘object’, but perhaps ‘will-notfall-when-unsupported-object’, or something along these lines. However, it’s quite likely that this abstract representation will fail to yield successful predictions again in the future. After all, the general category of things that do not fall when unsupported encompasses different kinds of objects that behave in very different ways like birds, insects, air balloons, airplanes, etc . At this point, the representation may be de-stabilized again, and we will go through another cycle of stabilization – de-stabilization – re-

 Speed : - . Empirical evidence for dopamine effects on neurons’ preferential responses can also be found in task-switching studies, where subjects need to constantly change the categories under which they are asked to classify various stimuli for example, ‘living animals’, ‘dogs’, ‘collies’, etc . )reedman et al. have found that the same neurons that responded preferentially to some features in one task start responding preferentially to other features in a new task, when a previously used category is no longer appropriate. This change is also effected by dopaminergic circuitries.

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 The Pragmatic View of Demonstrative Thought II : Object Representation

stabilization. But as we move through these cycles our practical knowledge of objects is endowed with a higher degree of portability and objectivity, as we become able to represent objects in a variety of ways on the basis of different properties, learning the specificity of their behaviours as well as their more abstract structural relationships i.e., that they are all types of ‘physical objects’ . This is the sense, emphasized in chapter six, in which practical knowledge of objects is a way of moving spiralling in the cognitive space of ‘object’ in an intelligent and purposeful manner, along the dimensions of stabilization and dispositional set size. To improve our practical knowledge, in this picture, is to become better at moving in this cognitive space, moving through stabilization cycles in a more efficient manner as we sensibly expand our zone of competence. Here’s a more concrete example of how this development might proceed, as described by Ann Speed: Consider a young child learning the names of different animals. Presented with a husky, the child comes to associate the word dog with the appearance of the husky: its coloring, size, long fur, and multicolored eyes. If the husky is the only example of a dog the child encounters, he may initially have a difficult time rectifying the appearance of a pug with the word dog because of the surface differences between the two breeds: size, color, sound of their respective barks, even their behavior. However, in interacting with the pug and the husky, he comes to recognize similarities between them that make them both dogs: barking, personality characteristics, possession of four legs, chewing on objects, etc. He may also receive verbal feedback: Yes, that’ s a dog too! However, given only two exemplars, he has not fully learned the core set of features that are uniquely diagnostic to the category dog as opposed to other four-legged animals. Therefore, when confronted with a horse, he may initially behave as though it were a very large dog and offer it a bone. )eedback from the environment i.e., the horse not responding to the bone the way the husky did or from others i.e., That’ s not a dog: That’ s a horse! enables the child to continue to distinguish the features of an animal that indicate it is a dog as opposed to a horse. These core features that are present across a wide number of exemplars are what analogy researchers would call structural features. In terms of the importance of graded persistence, if this child lived in an environment where it was not useful to know the difference between a horse and a dog, the prediction is that this difference, and the separate multimodal representation of horse and dog in P)C would not survive: that they would devolve into a more general representation of animals with four legs and the local networks that had taken on temporary representation of horse and dog would either participate in this more general category or would tend to respond selectively to some other category that was behaviorally relevant in this  Speed also presents empirical evidence that the P)C is hierarchically organized, with the features and structural relations neurons respond to increasing in complexity and abstractness along the posterior and anterior axis of the prefrontal cortex.

A new role for sortal concepts 

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child’s strange world. Likewise, if this child lived in a situation where the distinction between husky and pug was behaviorally relevant, local circuits of neurons would take on the task of selectively responding to these different breeds. Speed :

. A new role for sortal concepts This last point has interesting consequences for a long-standing debate in the philosophy of language and mind, concerning the role of sortal concepts in singular representation and thought. )or many philosophers have insisted that it is not possible to represent a physical object tout court, in the absence of a more specific sortal concept like ‘dog’, ‘tree’ or ‘car’, which classifies the object as an object of a certain kind. There are different versions of what we may call the sortalist thesis concerning singular representation: John Campbell, for example , sees it as thesis on whether sortal concepts are required in order to delineate the boundaries of the object we purport to single out, a thesis that has its origins in Quine’s arguments for the inscrutability of reference and the ambiguity of pointing . Imogen Dickie, in contrast , construe it as thesis on whether knowledge of kind is required in order to be able to attribute properties to objects, given that which properties an object can have depends on the kind of object it is. But regardless of these different versions of sortalism, I will here focus on David Wiggins’ latest defence of this thesis, as it appears in his response to )ei Xu . Xu famously claimed that the more abstract category ‘physical object’, which in our terminology roughly corresponds to entities with canonical object properties, is a kind of sortal concept. In fact, she claims it is our very first sortal concept, which we deploy in our first months of life in order to individuate and keep track of entities in the world that exhibit these properties, before we are sensitive to kind information as a principle of individuation and maintenance of numerical identity. Wiggin’s response consists in pointing out that the very capacity to track an object in space already deploys some more specific knowledge of the object’s kind, which is supplied by our grasp of the sortal concept the object falls under. As objects of different kinds move and behave in different ways, in order to understand that it is the same object x which has moved from point A to point B  See also Goodman for a useful review of different versions of the sortalist thesis. Xu’s original formulation is bounded, coherent, three-dimensional physical object that moves as a whole Xu :

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 The Pragmatic View of Demonstrative Thought II : Object Representation

we need to deploy more specific knowledge that is sensitive to the particular ways in which x moves according to the kind of thing it is . Wiggins’ example involves a subject faced with a range of objects which are identical in every respect, except for one important detail: some are covered with a thin membrane that lets other objects pass through them, while others are completely solid. As we imagine these objects being thrown against one another, two possible things can happen: either two solid objects will hit each other and rebound, returning to their original position, or one will pass through the other and move to the other side of the room, if one of them happens to be of the kind with a membrane on it. Wiggins’ point is that if we are to know that an object has moved across the room, or that it has collided with another and returned to its original position, we need to be sensitive to the distinctive ways in which these different kinds of objects move. As he puts it: However simple it may appear, the intuitive cum pre-theoretical idea of an object’s moving from one place to another has half-hidden conceptual complexities. )or an object to move from point a to point b over d seconds it is not enough for there to be a dense succession of X-like objects at a dense succession of points between a and b at a dense succession of moments during the period d seconds. There is more than that to moving. To move, X needs to have a way of behaving – and any putative motion by X needs to cohere with that way of behaving. These necessities arise directly from the need for something to count as X’s moving, for something to count as X’s rebounding from things that lie on its path and for something else to count as X’s passing through what lies in its way. Wiggins :

But what exactly does ‘grasp of a sortal concept’ consists in, and how does it complement our more general knowledge of how objects behave? Wiggins’ proposal is that this more general understanding, specified in terms of canonical object properties, functions in cognition as a kind of ‘formal concept’: a more abstract determinable, which can only be applied to objects when complemented by a more specific determinate, which is a sortal concept. Wiggins specifies this abstract determinable as bounded, coherent, threedimensional object with some particular way of behaving, coming to be, being, being qualified and passing away” : . The role of the sortal concept, in this picture, is to determine a particular way of behaving, coming to be etc. Both the determinable and the determinate are essential to our capacity to single out particulars in the world, but they cannot be applied to objects independently of one another. Our more specific understanding of objects that is sensitive to kind-specific information already implicates a more general understanding that different kinds of objects bear certain structural higher-order similarities i.e., they are all kinds of material objects . And on the other hand, we can only mani-

A new role for sortal concepts 

 

fest our general understanding of objects by applying it to particular kinds of objects, which manifest canonical object properties in different ways. But now we may reasonably ask: how exactly does the more specific determinate – the sortal concept – interacts with our more general knowledge of objects in explaining our capacity to single out objects in the world? The most straightforward response would involve our capacity to explicitly apply a concept to the object, in the form of a demonstrative judgment like ‘this physical object is a bird’, where the sortal concept ‘’bird’ determines the particular ways in which the object behaves, comes to be etc. But of course, in order to be in a position to apply the concept in this manner, we must be already sensitive to the particular ways in which birds behave, come to be etc. It is this sensitivity which grounds our conceptual judgments about birds, and not the other way around. But how can we explain what it is for us to be sensitive to an object’s more specific way of behaving, in a way that does not presuppose prior grasp of the sortal concept that specifies it? According to Wiggins, this sensitivity is manifested in our experience, as we actively interact with objects in the world and track their spatial trajectories in time. As he puts it, picking up a thing out and tracing it through space and time is part and parcel with treating it as a thing with some specific way of behaving… so as soon as one does treat the thing so, one is somewhere en route to the grasp of the sortal concept” Wiggins : . The idea of one being ‘en route’ to the grasp of a sortal concept suggests that this more specific knowledge may come in degrees, and may be manifested in some contexts but in others. To illustrate with an example, if we chase a Brazilian three-banded armadillo behind an obstacle, and then search behind the obstacle and find an almost perfect sphere instead of the usual four-legged animal we are familiar with, in the absence of background knowledge about armadillos we may take this to be a numerically distinct object. But as we continue to interact with objects of this kind, our predictive failures and successes concerning its possible behaviours will lead to successive stabilization and destabilization cycles, thus providing us with a more flexible and robust understanding that is increasingly more sensitive to the particular ways in which different kinds of object behaves. As Wiggins puts it, Grasping a sort is grasping a mode of activity, it is irreducibly practical, and it is graduated … so soon as a conscious subject begins to treat a thing to be individuated as possessed of a nature of particular mode of activity, this subject is already exercising some however minimal or tentative experimental conception of a specific kind of thing. Wiggins : , my emphasis

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 The Pragmatic View of Demonstrative Thought II : Object Representation

The theory of practical knowledge advanced in this book, supported by flexible abstract representations in the P)C and P)C-specific neurobiological structures, allows us to make sense of Wiggins’ claim. In accordance with our theory, this sensitivity to kind-specific ways of behaving is an integral part of our practical knowledge of objects, manifested in stabilization and de-stabilization cycles in the P)C that allow neurons to reconfigure and develop preferential responses to features that are more specific to certain kinds of objects. This sensitivity, as Wiggins himself is happy to admit, is graded, and may be manifested in some contexts but not in others. To conclude, I agree with Wiggins that our general knowledge of objects, manifested in our sensitivity to canonical object properties, is mutually dependent on more specific knowledge that is sensitive to kind-specific information. Many philosophers have taken this mutual interdependence to imply that our capacity to single out particulars in the world must be supplemented by a grasp of the sortal concept the object falls under. But although there is often some lack of clarity as to what it means to have a grasp of a sortal concept, here I offer a way of making sense of these observations that is compatible with Wiggins’ claims, without appealing to more sophisticated forms of conceptual knowledge. My suggestion is that the relevance of the sortalist thesis may be captured by the interplay between our general knowledge of objects and our sensitivity to kind-specific information in our active interactions with objects. According to the present theory this is manifested in the way our abstract representations go through stabilization and de-stabilization cycles, as a function of the failures and successes of our object-directed activities in the world. This allows us to account for the role of sortals in singular representation and thought in a naturalist and pragmatist theory of representation, which puts special emphasis on the flexibility of object representations in the prefrontal cortex and the role of dopaminergic circuits in reconfiguring these representations. This endows our practical knowledge of objects with a higher degree of portability and objectivity, as we become more sensitive to the particular ways in which objects of different kinds behave. But there need not be a precise point where we become able to bring an object of perception into a more specific sortal concept. Our sensitivity to kind-specific information, as I have been arguing, comes in degrees, and is irreducibly practical. As Wiggins puts it, We miss something important if we treat as open or shut the question whether a particular subject’s capacity to trace what is in fact a duck or a dog or a car involves mastery of the concept duck, dog, car. The success of some subject may suggest that, however inchoately,

Final considerations 



he or she is getting hold of these concepts and the correlative natures of particular kinds of things. Wiggins :

And what we miss is, precisely, what I’ve been trying to capture with the pragmatic view: that the capacity to apprehend our external environment as structured into individuals is not an all-or-nothing matter, but something that comes in degrees. Correspondingly, our ascriptions of singular content should be sensitive to this fact, which puts significant constrains on how our theories of singular representation and thought should be construed. The pragmatic view of demonstrative thought which I have proposed in this book is an attempt to do justice to these observations and meet these constraints.

.

)inal considerations

I started out this book raising the following question: how can we explain our capacity to think about particular objects in the world? I suggested that in order to do that, our theory should explain how a subject can be in a position to engage in object-directed mental activities with singular demonstrative contents: to make judgments about perceived objects, visualize them in one’s mind from a different angle, imagine what they would look like with different surface features, etc. What unifies these activities is, precisely, their common singular demonstrative content, which represents the perceived object that is the target of one’s mental activities. The specification of demonstrative thought in terms of ‘object-directed mental activities with singular demonstrative contents’ is not accidental, and point to two things our theory should be able to account for: first of all, how a subject’s mental activities can be connected to particular objects in the world the ‘demonstrative’ element , and secondly, what makes it the case that what is represented in the content of these activities are particular objects rather than, say, recurrent instances of property-kinds the ‘singular’ element . Although it is hardly controversial that the demonstrative element must be elucidated in perception – at the risk of leaving mind and world unconnected – things are less clear when it comes to the singular element. )or according to a longstanding tradition in philosophy, leading back to the writings of Strawson ns , Quine , Evans and more recently revived by Hatfield , the capacity to represent individual objects requires conceptual knowledge, and is linked to our adopting a more disengaged and reflective perspective upon that which we purport to think about.

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 The Pragmatic View of Demonstrative Thought II : Object Representation

A natural reaction on the part of philosophers who thought this approach to be overly intellectualistic was to explain both the singular and the demonstrative element at the more primitive level of perception. Combined with recent advances in cognitive science that suggest that our perceptual systems are naturally tuned to the tasks of individuating and tracking medium-sized threedimensional objects on the basis of spatiotemporal information alone, this gave rise to perceptualism: a theoretical approach that seeks to explain singular representation at the more primitive level of perception, through low-level perceptual processes that function in a manner analogous to that in which demonstratives function in language: by picking out an object ‘directly’, so to speak, without any conceptual or descriptive intermediary, so that this object may be further examined by higher cognitive processes. The perceptualist’s efforts, however, are hindered by the limited scope of the perceptual processes and mechanisms posited in her theory. Although the conceptualist would hardly dispute the fact that these processes put us in contact with what are in fact objects, there is nothing in these processes that suggest that the subject whose mental states we’re analysing is capable of apprehending her external environment as structured into individuals. If all we need to capture is a capacity to segregate and track perceptual elements in a visual array, the appeal to singular content here is explanatorily idle. A simpler content, structured in terms of instances of property-kinds, would do just as well. My goal in this book was to show that it is possible to overcome the limited explanatory power of perceptualism without falling into the intellectualist hold of the conceptualist. My suggestion was that we can attain this theoretical middle ground by adopting a pragmatist approach to demonstrative thought, where the capacity to think about particulars in the world is explained through our graded practical knowledge of what objects are and how they behave, acquired through our embodied interactions with objects in the world. I have called this approach the ‘pragmatic view’ of demonstrative thought. 0ow, it is usually thought that pragmatist approaches of this sort are incapable of doing their job: either because they come dangerously close to behaviourism, which we all know should be avoided at all costs, or because practical knowledge is restricted to more primitive forms of sensorimotor knowledge, and thus fares no better than perceptualism when it comes to explaining singular representation. In order to avoid these difficulties, I set out two tasks that needed to be accomplished: . To develop a novel theory of practical knowledge, which encompasses other forms of knowledge besides sensorimotor knowledge with various degrees of portability and objectivity;

Final considerations 

.



To state the neurobiological structures and mechanisms that support this conception of practical knowledge, and present empirical evidence that our knowledge of objects indeed develops in the manner suggested by the theory.

I have taken care of the first point in chapter six, where an alternative theory of practical knowledge was advanced in terms of the notion of the ‘cognitive space’. According to this proposal, practical knowledge of a certain subject matter p can be understood as a capacity to ‘move’ in the cognitive space of p within a certain zone of competence. At first, it might be that the zone of competence is restricted to sensorimotor knowledge, but it is possible to expand this zone of competence by adding novel circumstances to what I’ve called ‘the dispositional set’, and move through successive cycles of stabilization and destabilization. I have then applied this theory to the case of objects in chapter seven. In order to address point above I have introduced the ‘graded knowledge approach’ championed by psychologists like Yuko Munakata, 0icolas Rougier and Ann Speed among others . Munakata’s connectionist models and experiments helped us understand how object representations in young infants may strengthen as a function of their experience in the world, while Rougier and Speed have provided the neurobiological bases for the processes of natural stabilization and de-stabilization respectively. The result is a novel way of looking at singular representation and demonstrative thought, which ties it very closely to our embodied interactions with objects in the world, and which assigns a central role for practical knowledge to play in the theory. In defending this view in the course of this dissertation I hope to have accomplished two things: )irst of all, I hope to have attained an intermediary position in the logical space of singular representation and demonstrative thought, somewhere between perceptualist and conceptualist theories. This intermediary position should be of interests to philosophers of both perceptualist and conceptualist inclinations: to the former, who insist in accounting for singular representation without appealing to more sophisticated forms of conceptual knowledge, and to the latter, who often complain that low-level perceptual processes and mechanisms give us too little in the way of a subject’s psychological and epistemic capacities vis-à-vis individual objects in the world. And secondly, to have cleared the way for a more pragmatist approach to the theory of mental representation. In contrast to what I have called the ‘orthodox view’ of practical knowledge, the present theory suggests that practical

   The Pragmatic View of Demonstrative Thought II : Object Representation knowledge can play a much more central role in our cognitive life than it has been previously supposed, firmly rooted in neurobiological processes and mechanisms that conform to what the empirical sciences tell us about the mind. Even if one disagrees with the details of the pragmatic view as I present them here, if we allow ourselves to extend the notion of ‘practical knowledge’ beyond the narrow confines of sensorimotor knowledge we open doors to a new and exciting territory worth exploring, where pragmatist views may be developed and applied to this and to other related domains. To end with a provocative quote from Cussins, The semantic tradition since )rege has explored only a partial sub-space of the possible territory available to the representational theory: [but] a range of the theoretical options which have been assumed to be unavailable can be legitimately pursued, and … the payoff may be handsome. In other words: one hundred years after Über Sinn und Bedeutung how about looking over here?! Cussins :

Bibliography Aglioti, S., DeSouza, J.F., Goodale, M.A. Size-contrast Illusions Deceive the Eye but 0ot the Hand. Current Biology 6 , 6 9–6 . 99 . Allport, Alan. Visual Attention. In: Foundations of Cognitive Science, edited by Michael I. Posner, 6 –6 . Cambridge, MA: MIT Press. 9 9. Alvarez, G., Cavanagh, P.. Independent Resources for Attentional Tracking in the Left and Right Visual Hemifields. Psychological Science 6 , 6 –64 . . Asby, F.G., Ennis, J.M. The Role of the Basal Ganglia in Category Learning. The Psychology of Learning and Motivation 46, – 6. 6. Awh, E., Pashler, H.. Evidence for Split Attentional Foci. Journal of Experimental Psychology. Human Perception and Performance 6 April , 4– 46. . Bach, Kent. Thought and Reference. Oxford: Oxford University Press. 9 . Bahrami, Bahador. Object Property Encoding and Change Blindness in Multiple Object Tracking. Visual Cognition 0ovember , 949–96 . . Baillargeon, Renee. Object Permanence in / - and 4 / -Month-Old Infants. Developmental Psychology , 6 –64. 9 . Baillargeon, Renee. Young Infants’ Expectations About Hidden Objects: a Reply to Three Challenges. Developmental Science , – . 999. Bayne, T., Montague, M. Cognitive Phenomenology. Oxford: Oxford University Press, USA. . Bayne, Tim. Perception and the Reach of Phenomenal Content. Philosophical Quarterly 9 6, –4 4. 9. Bennett, A. T. Do Animals Have Cognitive Maps? The Journal of Experimental Biology 99 Pt January , 9– 4. 996. Bermudez, Jose Luis. Thinking Without Words. Oxford: Oxford University Press. Bermudez, Jose Luis. Philosophy Of Psychology: A Contemporary Introduction. London: Routledge. . Bermudez, Jose Luis. The Object Properties Model of Object Perception: Between the Binding Model and the Theoretical Model. Journal of Consciousness Studies 4 s 9- , 4 –6 . . Block, 0ed. On a Confusion About the Function of Consciousness. Behavioral and Brain Sciences , –4 . 99 . Brewer, Bill. Perception and Reason. Oxford: Oxford University Press. 999. Broadbent, Donald E. Decision and Stress. London: Academic Press. 9 . Burge, Tyler. Belief De Re. The Journal of Philosophy 4 6 June , . 9 . Burge, Tyler. Origins of Objectivity. Oxford: Oxford University Press. . Campbell, John. The Role of Physical Objects in Spatial Thinking. In: Spatial Representation: Problems in Philosophy and Psychology, edited by 0aomi Eilan, R. McCarthy, Bill Brewer. Oxford: Blackwell. 99 . Campbell, John. Past, Space, and Self. Cambridge, MA: MIT Press. 994. Campbell, John. Sense, Reference and Selective Attention. Proceedings of the Aristotelian Society , –9 . 99 . Campbell, John. Reference and Consciousness. Oxford: Oxford University Press. . Carey, Susan. The Origin of Concepts. Oxford: Oxford University Press. 9.



 Bibliography

Carey, S., Xu, F. Infants’ Knowledge of Objects: Beyond Object Files and Object Tracking. Cognition - June , 9– . . Carrasco, M., Ling, S., Read, S. Attention Alters Appearance. 0ature 0euroscience March , – . 4. Carrasco, M., McElree, B.Covert Attention Accelerates the Rate of Visual Information Processing. Proceedings of the 0ational Academy of Sciences 9 9 April 4 , 6 – 6 . . Castaneda, Hector-0eri. ‘He’: A Study in the Logic of Self-Consciousness. Ratio December , – . 966. Castaneda, Hector-0eri. Indicators and Quasi-Indicators. American Philosophical Quarterly 4 , – . 96 . Chalmers, David J. Phenomenal Concepts and the Explanatory Gap. In: Phenomenal Concepts and Phenomenal Knowledge: 0ew Essays on Consciousness and Physicalism, edited by T. Alter and S. Walter. Oxford: Oxford University Press. . Clark, Austen. A Theory of Sentience. 0ew York: Oxford University Press. . Clark, Romane L. Sensing, Perceiving, Thinking. Grazer Philosophische Studien , – 9 . 9 9. Courtney, S. M., Petit, L., Haxby, J. V., Ungerleider, L. G. The Role of Prefrontal Cortex in Working Memory: Examining the Contents of Consciousness. Phil. Trans. R. Soc. London B , 9. 99 . Cussins, Adrian. Content, Embodiment, and Objectivity: The Theory of Cognitive Trails. Mind 4 4 , 6 – . 99 . Cussins, Adrian. Subjectivity, Objectivity and Frames of Reference in Evans’s Theory of Thought. The Electronic Journal of Analytic Philosophy 6 . 99 . Cussins, Adrian. Content, Conceptual Content, and 0onconceptual Content. In: Essays on 0onconceptual Content, edited by York H. Gunther. Cambridge, MA: MIT Press. . Daprati, E., Gentilucci, M. Grasping an Illusion. 0europsychologia December, – . 99 . Dehaene, S., Cohen, L. 994. Dissociable Mechanisms of Subitizing and Counting: 0europsychological Evidence from Simultanagnosic Patients. Journal of Experimental Psychology. Human Perception and Performance October,: 9 –9 . 994. Dennis, John L., and Pylyshyn, Z. W. Effect of Object Discriminability on Multiple Object Tracking. Journal of Vision 0ovember , 4 – 4 . . Desimone, R., Duncan, J. 0eural Mechanisms of Selective Visual Attention. Annual Review of 0euroscience , 9 – . 99 . Dickie, Imogen. The Sortal Dependence of Demonstrative Reference. European Journal of Philosophy , 4-6 . 4. Dokic, J., Pacherie, E. On the Very Idea of a Frame of Reference. In: Space in Languages: Linguistic Systems and Cognitive Categories, edited by M. Hickman and .S Robert, 9– . Amsterdam/Philadelphia: John Benjamins. 6. Driver, J., Davis, G., Russell, C., Turatto, M., Freeman, E. Segmentation, Attention and Phenomenal Visual Objects. Cognition - June , 6 –9 . . Driver, J., Frith, C. Shifting Baselines in Attention Research. 0ature Reviews 0euroscience 0ovember , 4 – 4 . . Duncan, J., Humphreys, G. W. Visual Search and Stimulus Similarity. Psychological Review 96 July , 4 –4 . 9 9.

Bibliography 



Egeth, H. E., Leonard, C. J., Palomares, M. The Role of Attention in Subitizing: Is the Magical 0umber ? Visual Cognition 6 4 , 46 –4 . . Eilan, 0aomi. Consciousness, Acquaintance and Demonstrative Thought. Philosophy and Phenomenological Research 6 ,4 – . . Eilan, 0., McCarthy, R., Brewer, B. Eds .Spatial Representation. Problems in Philosophy and Psychology. Oxford: Blackwell. 99 . Evans, Gareth. The Varieties of Reference. Oxford: Oxford University Press. 9 . Fodor, Jerry A. The Language of Thought. Cambridge, MA: Harvard University Press. 9 . Frank, Michael J. Dynamic Dopamine Modulation in the Basal Ganglia: a 0eurocomputational Account of Cognitive Deficits in Medicated and 0onmedicated Parkinsonism. Journal of Cognitive 0euroscience January , – . . Franz, V. H., Gegenfurtner, K. R., Bülthoff, H. H., Fahle, M. Grasping Visual Illusions: 0o Evidence for a Dissociation Between Perception and Action. Psychological Science January , – . . Freedman, David J., Riesenhuber, M., Poggio, T., Miller, E. K. Visual Categorization and the Primate Prefrontal Cortex: 0europhysiology and Behavior. Journal of 0europhysiology August , 9 9–94 . . Friedman-Hill, S. R., Robertson, L. C., Treisman, A. 99 . Parietal Contributions to Visual Feature Binding: Evidence from a Patient with Bilateral Lesions. Science 69 August , – . 99 . Gallistel, Charles R. The Organization of Learning. Cambridge, MA: Mit Press. 99 . Goodale, M. A., Meenan, J. P., Bülthoff, H. H., 0icolle, D. A., Murphy, K. J., Racicot, C.I. Separate 0eural Pathways for the Visual Analysis of Object Shape in Perception and Prehension. Current Biology 4 July , 6 4–6 . 994. Goodale, M. A., Milner, A. D. Separate Visual Pathways for Perception and Action. Trends in 0eurosciences January , – . 99 . Goodale, M. A., Wolf, M.. 9. Vision for Action. In: Computation, Cognition, and Pylyshyn, edited by D. Dedrick and L. Trick, – 6. Cambridge, MA: MIT Press. 9. Goodman, Rachel. Why and How 0ot to Be a Sortalist About Thought. Philosophical Perspectives 6 , – . . Gopnik, A., Meltzoff, A. Words, Thoughts, and Theories. Cambridge, MA: Mit Press. 99 . Gould, James L. The Locale Map of Honey Bees: Do Insects Have Cognitive Maps? Science 4 May 6 , 6 – 6 . 9 6. Gredebäck, G., Johnson, S., von Hofsten, C. Eye Tracking in Infancy Research. Developmental 0europsychology , – 9. . Grush, Rick. . Skill Theory V . : Dispositions, Emulation, and Spatial Perception. Synthese 9 , 9–4 6. . Gunther, York H. Essays on 0onconceptual Content. Cambridge, MA: MIT Press. . Haffenden, A. M., Goodale, M. A. The Effect of Pictorial Illusion on Prehension and Perception. Journal of Cognitive 0euroscience January , – 6. 99 . Hatfield, Gary C. Perception and Cognition: Essays in the Philosophy of Psychology. Oxford: Oxford University Press. 9. Hawley, K., Macpherson, F. Eds . The Admissible Contents of Experience. Oxford: WileyBlackwell. . Hayhoe, Mary. Vision Using Routines: A Functional Account of Vision. Visual Cognition , 4 – 64. .



 Bibliography

Heck, Richard. Are There Different Kinds of Content? In: Contemporary Debates in Philosophy of Mind, edited by J. Cohen and B. McLaughlin, – . Oxford: Blackwell. . Hespos, S. J., Baillargeon, R. Reasoning About Containment Events in Very Young Infants. Cognition March , – 4 . . Hillyard, S. A., Teder-Sälejärvi, W.A., Münte, T. F. Temporal Dynamics of Early Perceptual Processing. Current Opinion in 0eurobiology April , – . 99 . Hoffman, James E. Visual Attention and Eye Movements. In: Attention, edited by H. Pashler, 9– . Hove, Uk: Psychology Press. 99 . Hollingworth, A., Henderson, J. M. Sustained Change Blindness to Incremental Scene Rotation: a Dissociation Between Explicit Change Detection and Visual Memory. Perception & Psychophysics 66 July , – . 4. Hopfinger, J.B., Luck, S. J., Hillyard, S. A. Selective Attention: Electrophysiological and 0euromagnetic Studies. In: The Cognitive 0eurosciences, edited by M.S. Gazzaniga, 6 – 4. Cambridge, MA: MIT Press. 4. Horgan, T. E., Tienson, J. L., Graham, G. The Phenomenology of First-Person Agency. In: Physicalism and Mental Causation, edited by S. Walter and H.D. Heckmann. Imprint Academic. . Houston-Price, C., 0akai, S. Distinguishing 0ovelty and Familiarity Effects in Infant Preference Procedures. Infant and Child Development 4 0ovember , 4 – 4 . 4. Huntley-Fenner, G., Carey, S., Solimando, A. . Objects Are Individuals but Stuff Doesn’t Count: Perceived Rigidity and Cohesiveness Influence Infants’ Representations of Small Groups of Discrete Entities. Cognition October , – . . Jacob, P., Jeannerod, M. Ways of Seeing: The Scope and Limits of Visual Cognition. Oxford: Oxford University Press. . James, William. The Principles of Psychology. Dover Publications. 9 . Jeannerod, Marc. The Cognitive 0euroscience of Action. Oxford: Wiley-Blackwell. 99 . Jog, M. S., Kubota, Y., Connolly, C. I., Hillegaart, V., Graybiel, A. M. Building 0eural Representations of Habits. Science 6 44 0ovember 6 , 4 – 49. 999. Johnson, S. P., Amso, D., Slemmer, J. A. Development of Object Concepts in Infancy: Evidence for Early Learning in an Eye-tracking Paradigm. Proceedings of the 0ational Academy of Sciences September , 6 – . . Jung, Eva-Maria, 0ewen, Albert. Knowledge and Abilities: The 0eed for a 0ew Understanding of Knowing-How. Phenomenology and the Cognitive Sciences 9 , - . . Kahneman, D., Treisman, A., Gibbs, B. J. The Reviewing of Object Files: Object-specific Integration of Information. Cognitive Psychology 4 April , – 9. 99 . Kanwisher, 0ancy. 0eural Events and Perceptual Awareness. Cognition 9 - April , 9– . . Kaplan, David. Demonstratives. In: Themes From Kaplan, edited by J. Almog, J. Perry, and H. Wettstein, 4 – 6 . 0ew York: Oxford University Press. 9 9a. Kaplan, David. Afterthoughts. In: Themes From Kaplan, edited by J. Almog, J. Perry, and H. Wettstein, 6 –6 4. 0ew York: Oxford University Press. 9 9b. Kastner, S., Ungerleider, L. G. Mechanisms of Visual Attention in the Human Cortex. Annual Review of 0euroscience , – 4 . . Kelly, Sean D. . Demonstrative Concepts and Experience. Philosophical Review , 9 –4 . . Kentridge, R. W., Heywood, C. A., Weiskrantz, L. Attention Without Awareness in Blindsight. Proceedings of the Royal Society of London B 66, – . 999.

Bibliography 

 

Kentridge, R. W., Heywood, C. A., Weiskrantz, L. Spatial Attention Speeds Discrimination Without Awareness in Blindsight. 0europsychologia 4 6 , – . 4. Kentridge, R. W., 0ijboer, T. C. W., Heywood, C.A. Attended but Unseen: Visual Attention Is 0ot Sufficient for Visual Awareness. 0europsychologia 46 February , 64– 69. . Kharitonova, M., Munakata, Y. The Role of Representations in Executive Function: Investigating a Developmental Link Between Flexibility and Abstraction. Frontiers in Psychology , 4 . . Klatzky, Roberta L. Allocentric and Egocentric Spatial Representations: Definitions, Distinctions, and Interconnections. In: Spatial Cognition: An Interdisciplinary Approach to Representing and Processing Spatial Knowledge, edited by Christian Freska, Christopher Chatham, and Karl F. Wender, – . London: Springer. 99 . Kolb, B., Whishaw, I. Q. Fundamentals of Human 0europsychology. 0ew York: Worth Publishers. 9. Kotovsky, L., Baillargeon, R. The Development of Calibration-based Reasoning About Collision Events in Young Infants. Cognition 6 July , – . 99 . Kowler, E., Anderson, E., Dosher, B., Blaser, E. The Role of Attention in the Programming of Saccades. Vision Research July , 9 – 9 6. 99 . Lamme, V. A. Why Visual Attention and Awareness Are Different. Trends in Cognitive Sciences , – . . Lamme, .V A., Roelfsema, P.R. The Distinct Modes of Vision Offered by Feedforward and Recurrent Processing. Trends in 0eurosciences 0ovember , – 9. . Land, Michael F. Eye Movements and the Control of Actions in Everyday Life. Progress in Retinal and Eye Research May , 96– 4. 6. Latour, Bruno. Science in Action: How to Follow Scientists and Engineers Through Society. Cambridge: Harvard University Press. 9 . Levine, Joseph. Demonstrative Thought. Mind and Language , 69– 9 . . Lewis, David. Attitudes De Dicto and De Se. Philosophical Review 4, – 4 . 9 9. Loar, Brian. Phenomenal States II. In: The 0ature of Consciousness: Philosophical Debates, edited by 0.J. Block, G. Guzeldere, and O. Flanagan. Cambridge, MA: The Mit Press. 99 . Marr, David. Vision. San Francisco: Freeman. 9 . Martin, Michael G. F. The Shallows of the Mind. Proceedings of the Aristotelian Society, –9 . 99 . Matthen, Mohan. Seeing, Doing, and Knowing: A Philosophical Theory of Sense Perception. Oxford University Press. . Matthen, Mohan. Visual Demonstratives. In: Perception, Realism, and The Problem of Reference, edited by A. Raftopoulos and P. Machamer. Cambridge University Press. . McDowell, John. Mind and World. Cambridge: Harvard University Press. 994. McMains, S. A., Somers, D. C. Multiple Spotlights of Attentional Selection in Human Visual Cortex. 0euron 4 4 May , 6 –6 6. 4. Mc0amara, T. P., Shelton, A. L.. Cognitive Maps and the Hippocampus. Trends in Cognitive Sciences August , – . . Menzel, E. W. Chimpanzee Spatial Memory Organization. Science 0ew York, 0.Y. 4 0ovember , 94 –94 . 9 . Miller, E. K., Erickson, C. A., Desimone, R. 0eural Mechanisms of Visual Working Memory in Prefrontal Cortex of the Macaque. The Journal of 0euroscience 6 6 , 4- 6 . 996. Miller, E. K., Cohen, J. D. An Integrative Theory of Prefrontal Cortex Function. Annual Review of 0euroscience 4, 6 – . .



 Bibliography

Miller, E. K., Desimone, R. Parallel 0euronal Mechanisms for Short-term Memory. Science 6 46 January , – . 994. Millikan, Ruth Garrett. On Clear and Confused Ideas: An Essay About Substance Concepts. Cambridge: Cambridge University Press. . Milner, A. D., Goodale, M. A. The Visual Brain in Action. Oxford: Oxford University Press. 99 . Munakata, Y., Herd, S. A., Chatham, C. H., Depue, B. E., Banich, M. T., O’Reilly, R. C. A Unified Framework for Inhibitory Control. Trends in Cognitive Sciences October , 4 –4 9. . Munakata, Y., McClelland, J.L., Johnson, M. H., Siegler, R. S. Rethinking Infant Knowledge: Toward an Adaptive Process Account of Successes and Failures in Object Permanence Tasks. Psychological Review 4 4 October , 6 6– . 99 . Munakata, Y., Yerys, B. E. All Together 0ow: When Dissociations Between Knowledge and Action Disappear. Psychological Science 4 July , – . . Munakata, Yuko. Infant Perseveration: Rethinking Data, Theory, and the Role of Modelling. Developmental Science , – . 99 . Munakata, Yuko. Graded Representations in Behavioral Dissociations. Trends in Cognitive Sciences July , 9– . . Munakata, Yuko, and James L. McClelland. Connectionist Models of Development. Developmental Science 6 4 , 4 -4 9. . 0akayama, K., He, Z. J., Shimojo, S. Visual Surface Representation: a Critical Link Between Lower-level and Higher Level Vision. In: Visual Cognition: An Invitation to Cognitive Science, edited by S. M. Kosslyn and D. 0. Osherson, – . Cambridge, MA: MIT Press. 99 . 0anay, Bence. Attention and Perceptual Content. Analysis , 6 – . . 0anay, Bence. Perceiving Pictures. Phenomenology and the Cognitive Sciences 4 , 46 – 4 . . 0oë, Alva. Against Intellectualism. Analysis 6 , – 9 . . 0oë, A., O’Regan, K. J. On the Brain-Basis of Visual Consciousnes: A Sensorimotor Account. In: Vision and Mind: Selected Readings in the Philosophy of Perception, edited by Alva 0oë and Evan Thompson. Cambridge, MA: Mit Press. . 0oles, 0. S., Scholl, B. J., Mitroff, S.R. The Persistence of Object File Representations. Perception & Psychophysics 6 February , 4– 4. . O’Keefe, J., 0adel, L. The Hippocampus as a Cognitive Map. Oxford: Clarendon Press. 9 . O’Regan, K. J., 0oë, A. A Sensorimotor Account of Vision and Visual Consciousness. Behavioral and Brain Sciences 4 , –9 . . O’Reilly, R. C., Frank, M. J. Making Working Memory Work: A Computational Model of Learning in the Prefrontal Cortex and Basal Ganglia. 0eural Comput. February , – . 6. Oksama, L., Hyönä, J. Is Multiple Object Tracking Carried Out Automatically by an Early Vision Mechanism Independent of Higher-order Cognition? An Individual Difference Approach. Visual Cognition , 6 –6 . 4. Olivers, C. 0. L., Watson, D. G. Subitizing Requires Attention. Visual Cognition 6 4 May , 4 9–46 . . Pacherie, Elisabeth. Perspectival and Objective Representations of Space and Time. In: Proc. of the 4th European Congress of Analytic Philosophy. Lund, Sweden. . Peacocke, Christopher. Sense and Content: Experience, Thought, and Their Relations. Oxford: Oxford University Press. 9 . Peacocke, Christopher. A Study of Concepts. Cambridge, MA: MIT Press. 99 .

Bibliography 



Peacocke, Christopher. Intuitive Mechanics, Psychological Reality and the Idea of a Material Object. In: Spatial Representation: Problems in Philosophy and Psychology, edited by 0aomi Eilan, Rosaleen McCarthy and Bill Brewer, 6 – 6. Oxford: Oxford University Press. 99 . Perry, John. The Problem of the Essential Indexical. 0oûs December , – . 9 9. Perry, John. Time, Consciousness and the Knowledge Argument. In: The Importance of Time: Proceedings of the Philosophy of Time Society, 99 . Dordrecht: Kluwer Academic Pub. . Pick, H.L. Organization of Spatial Knowledge in Children. In: Spatial Representation: Problems in Philosophy and Psychology, edited by 0aomi Eilan, Rosaleen McCarthy, and Bill Brewer, –4 . Oxford: Oxford University Press. 99 . Pick, H.L., Lockman, J. J. Development of Spatial Cognition in Children. In: Mind, Child, Architecture, edited by J.C. Baird and A.D. Lutkas, 4 –6 . Hanover, 0H: University Press of 0ew England. 9 . Le Poidevin, Robin. Egocentric and Objective Time. Proceedings of the Aristotelian Society 99, 9– 6. 999. Posner, M I. Orienting of Attention. The Quarterly Journal of Experimental Psychology February , – . 9 . Prinz, Jesse. Beyond Appearances : The Content of Sensation and Perception. In: Perceptual Experience, edited by T.S. Gendler and J. Hawthorne. Oxford: Oxford University Press. 6. Pylyshyn, Z., Burkell, J., Fisher, B., Sears, C., Schmidt, W., Trick, L. Multiple Parallel Access in Visual Attention. Canadian Journal of Experimental Psychology / Revue Canadienne De Psychologie Expérimentale 4 June , 6 – . 994. Pylyshyn, Z., Storm, R. W. Tracking Multiple Independent Targets: Evidence for a Parallel Tracking Mechanism. Spatial Vision , 9– 9 . 99 . Pylyshyn, Z., Annan, V. J. Dynamics of Target Selection in Multiple Object Tracking MOT . Spatial Vision 9 6 , 4 - 4. Pylyshyn, Zenon. Is Vision Continuous with Cognition? The Case for Cognitive Impenetrability of Visual Perception. Behavioral and Brain Sciences , 4 – 6 . 999. Pylyshyn, Zenon. Visual Indexes, Preconceptual Objects, and Situated Vision. Cognition , – . . Pylyshyn, Zenon. Things and Places: How the Mind Connects With the World. Cambridge, MA: MIT Press. . Quine, W. V. O. Word and Object. Cambridge: The Mit Press. 96 . Quine, W. V. O. From Stimulus to Science. Cambridge: Harvard University Press. 99 . Raftopoulos, Athanassios. Cognition and Perception: How Do Psychology and 0eural Science Inform Philosophy? Cambridge, MA: Mit Press. 9a. Raftopoulos, Athanassios. Reference, Perception, and Attention. Philosophical Studies 44 , 9– 6 . 9b. Raftopoulos, A., Müller, V. C. 0onconceptual Demonstrative Reference. Philosophy and Phenomenological Research , – . 6. Rainer, G., Miller, E. K. Effects of Visual Experience on the Representation of Objects in the Prefrontal Cortex. 0euron , 9- 9. . Rainer, G., Ranganath, C. R. Coding of Objects in the Prefrontal Cortex of Humans and Monkeys. The 0euroscientist , 6- . .



 Bibliography

Recanati, François. Perspectival Thought: A Plea for Moderate Relativism. Oxford: Oxford University Press. . Rensink, R. A., Enns, J.T. Early Completion of Occluded Objects. Vision Research - 6 August , 4 9– . 99 . Rensink, Ronald A. The Dynamic Representation of Scenes. Visual Cognition - , –4 . . Reynolds, J. H., Pasternak, T., Desimone, R. . Attention Increases Sensitivity of V4 0eurons. 0euron 6 June , – 4. . Reynolds, J.H., Desimone, R. 0eural Mechanisms of Attentional Selection. In: Visual Attention and Cortical Circuits, edited by J. Braun, C. Koch, and J. Davis, – 6. Cambridge, MA: MIT Press. . Robertson, L., Treisman, A., Friedman-Hill, S., Grabowecky, M. The Interaction of Spatial and Object Pathways: Evidence from Balint’s Syndrome. J. Cogn. 0eurosci. 9 May , 9 – . 99 . Roelfsema, Pieter R. Elemental Operations in Vision. Trends in Cognitive Sciences 9 May , 6– . . Rougier, 0. P., 0oelle, D. C., Braver, T. S., Cohen, J. D., O’Reilly, R. C. Prefrontal Cortex and Flexible Cognitive Control: Rules Without Symbols. Proceedings of the 0ational Academy of Sciences of the United States of America May , – 4 . . Di Russo, F., Spinelli, D., Morrone, M. C. Automatic Gain Control Contrast Mechanisms Are Modulated by Attention in Humans: Evidence from Visual Evoked Potentials. Vision Research 4 9 September , 4 – 44 . . Ryle, Gilbert. The Concept of Mind. London: Hutchinson and Co. 949. Saxe, R., Carey, S. The Perception of Causality in Infancy. Acta Psychologica - October , 44– 6 . 6. Scholl, Brian. Objects and Attention: The State of the Art. Cognition , –46. . Scholl, Brian. Can Infants’ Object Concepts Be Trained? Trends in Cognitive Sciences February , 49– . 4. Scholl, Brian. What Have We Learned About Attention from Multiple Object Tracking and Vice Versa ? In: Computation, Cognition, and Pylyshyn, edited by D. Dedrick and L. Trick, 49– . Cambridge, MA: MIT Press. 9. Sears, C. R., Pylyshyn, Z. Multiple Object Tracking and Attentional Processing. Canadian Journal of Experimental Psychology / Revue Canadienne De Psychologie Expérimentale 4 March , – 4. . Shinskey, Jeanne L. The Sound of Darkness: Why Do Auditory Cues Aid Infants’ Search for Objects Hidden by Darkness but 0ot by Visible Occluders? Developmental Psychology 44 6 0ovember , – . . Shinskey, J. L., Munakata, Y. Familiarity Breeds Searching: Infants Reverse Their 0ovelty Preferences When Reaching for Hidden Objects.” Psychological Science 6 August , 96– 6 . . Shinskey, J. L., Munakata, Y. Are Infants in the Dark About Hidden Objects? Developmental Science 6 June , – . . Shinskey, J. L., Munakata, Y. Something Old, Something 0ew: a Developmental Transition from Familiarity to 0ovelty Preferences with Hidden Objects. Developmental Science March , - 4. . Shoemaker, Sydney. Self-Knowledge and ‘Inner Sense’: Lecture I: The Object Perception Model. Philosophy and Phenomenological Research 4 , 49– 69. 994.

Bibliography 



Siegel, Susanna. The Role of Perception in Demonstrative Reference. Philosophers’ Imprint , – . . Smeets, J. B., Brenner, E. A 0ew View on Grasping. Motor Control July , – . 999. Smeets, J. B., Brenner, E. Independent Movements of the Digits in Grasping. Experimental Brain Research 9 July , 9 – . . Smith, A. D. The Problem of Perception. Harvard University Press. . Snowdon, Paul. Knowing How and Knowing That: A Distinction Reconsidered. Proceedings of the Aristotelian Society 4 , – . . Snyder, H. R., Banich, M. T., Munakata, Y. Choosing Our Words: Retrieval and Selection Processes Recruit Shared 0eural Substrates in Left Ventrolateral Prefrontal Cortex. Journal of Cognitive 0euroscience 0ovember , 4 – 4 . . Speaks, Jeff. Attention and Intentionalism. Philosophical Quarterly 6 9, – 4 . . Speed, Ann. Abstract Relational Categories, Graded Persistence, and Prefrontal Cortical Representation. Cognitive 0euroscience , 6– . . Spelke, E., Kestenbaum, R., Simons, D., Wein, D. Spatiotemporal Continuity, Smoothness of Motion and Object Identity in Infancy. The British Journal of Developmental Psychology , – 4 . 99 . Stanley, J., Williamson, T. Knowing How. Journal of Philosophy 9 , 4 –444. . Stazicker, James. Conscious Attention: Focussing The Mind. Unpublished ms. . Strawson, P. F. Individuals: An Essay in Descriptive Metaphysics. London: Routledge. 9 9. Streri, A., Féron, J. The Development of Haptic Abilities in Very Young Infants: From Perception to Cognition. Infant Behavior and Development September , 9 – 4. . Tacca, Michela C. Seeing Objects: The Structure of Visual Representation. Paderborn: Mentis. . Tolman, E.C. Cognitive Maps in Rats and Men. The Psychological Review 4 , 9– . 94 . Treisman, Anne. Feature Binding, Attention and Object Perception. Phil Trans R. Soc London B , 9 – 6. 99 . Treisman, Anne. Psychological Issues in Selective Attention. In: The Cognitive 0eurosciences, edited by M. Gazzaniga, 9– 44. Cambridge, MA: MIT Press. 4. Treisman, A., Gelade, G. A Feature-integration Theory of Attention. Cognitive Psychology January , 9 – 6. 9 . Treisman, A., Gormican, S. Feature Analysis in Early Vision: Evidence from Search Asymmetries. Psychological Review 9 January , –4 . 9 . Treue, Stefan. Perceptual Enhancement of Contrast by Attention. Trends in Cognitive Sciences October , 4 –4 . 4. Trick, L. M., Pylyshyn, Z. Why Are Small and Large 0umbers Enumerated Differently? A Limitedcapacity Preattentive Stage in Vision. Psychological Review January , – . 994. Tsal, Y. Do Illusory Conjunctions Support the Feature Integration Theory? A Critical Review of Theory and Findings. Journal of Experimental Psychology: Human Perception and Performance , 94–4 . 9 9. Tse, Peter U. Voluntary Attention Modulates the Brightness of Overlapping Transparent Surfaces. Vision Research 4 9 April , 9 – 9 . . Ungerleider, L. G., Haxby, J. V. ‘What’ and ‘Where’ in the Human Brain. Current Opinion in 0eurobiology 4 April , – 6 . 994.

  Bibliography Ungerleider, L. G., Mishkin, M. Two Cortical Visual Systems. In: Analysis of Visual Behavior, edited by D.J. Ingle, M.A. Goodale, and R.J.W. Mansfield, 49– 6. Boston: MIT Press. 9 . Vaidya, C. J., Gabrieli, J. D., Monti, L. A., Tinklenberg, J. R., Yesavage, J. A. Dissociation Between Two Forms of Conceptual Priming in Alzheimer’s Disease. 0europsychology 4 October , 6– 4. 999. Vecera, Shaun P. Toward a Biased Competition Account of Object-Based Segregation and Attention. Brain and Mind , – 4. . Warden, M. R., Miller, E. K. The Representation of Multiple Objects in Prefrontal 0euronal Delay Activity. Cerebral Cortex ,4 - . . Watzl, Sebastian. The 0ature of Attention. Philosophy Compass 6 , 4 – . . Wendelken, C., Munakata, Y., Baym, C., Souza, M., Bunge, S. A. Flexible Rule Use: Common 0eural Substrates in Children and Adults. Developmental Cognitive 0euroscience July : 9– 9. . Wiggins, David. Sortal Concepts: A Reply to Xu. Mind and Language &4 , 4 –4 . 99 . Wolfe, J. M., Cave, K. R., Franzel, S.L. Guided Search: An Alternative to the Feature Integration Model for Visual Search. Journal of Experimental Psychology: Human Perception and Performance August , 4 9–4 . 9 9. Wu, Wayne. Visual Attention, Conceptual Content, and Doing It Right. Mind 46 , – . . Wu, Wayne. What Is Conscious Attention? Philosophy and Phenomenological Research , 9 – . a. Wu, Wayne. Attention as Selection for Action. In: Attention: Philosophical and Psychological Essays. Oxford: Oxford University Press. b. Xu, Fei. From Lot’s Wife to a Pillar of Salt: Evidence That ‘Physical Object’ Is a Sortal Concept. Mind and Language &4 , 6 – . 99 . Yantis, Steven. Objects, Attention and Perceptual Experience. In: Visual Attention, edited by R.D. Wright, – 4. Oxford: Oxford University Press. 99 . Yantis, S., Hillstrom, A. P. Stimulus-driven Attentional Capture: Evidence from Equiluminant Visual Objects. Journal of Experimental Psychology. Human Perception and Performance February , 9 – . 994. Yeshurun, Y., Carrasco, M. Spatial Attention Improves Performance in Spatial Resolution Tasks. Vision Research 9 January , 9 – 6. 999.

Index Allport, Alan fn., Attention – and the computational-representational theory of mind 9 f. – and consciousness ff., – and demonstrative thought ff., 44ff., 4ff., f. f. – and feature binding see Feature Integration Theory – and motion-guiding vision f., f., f. – and multiple object tracking 96ff., 99ff. – affects perceptual processing 9, 6, 9, f. – alters perceptual appearances ff. – as selection for action , ff. – attentional blink f. – automatic attentional capture 6 , , 9 ff. – biased competition model f. – coherence theory of , f. – cognitive ff. – conscious 4ff., , 6 f., 6f. See also: experiential highlighting, phenomenal salience – covert fn., 6 f. – phenomenology of 4ff., 4 f., 4ff., 6 . See also: experiential highlighting, phenomenal salience – multifocal f., – object-based , f. – set-based – scientific notion of 4ff. – and subitizing f. – to thought ff. – without conscious awareness , 4 f. Bach, Kent Baillargeon, Renée f., 4 Balint's syndrome f. Bermudez, Jose Luis ff., 49 Blindsight 4f., 44ff., 6 Block, 0ed fn. Burge, Tyler , fn., 6, ,

Campbell, John fn., , 9, 4 ff, f., f., 4, ff., , Carey, Susan 4 , 4 , Carrasco, Marisa f. Castañeda, Hector-0eri 64fn. Causal indexicality f. Cognitive maps 6 ff., 94ff. Cognitive space ff., 44ff. Content – epistemic dimension of ff., 49ff. – of thought ff. – of perception fn., , ff., Cussins, Adrian fn., 4f., ff., ff., ff., 4, 6 Dickie, Imogen Dokic, Jérôme 6 fn. Dorsal visual stream

ff.

Early vision system 9 , Eilan, 0aomi 46 Evans, Gareth 9 , f., 4 , 64ff, f., ff. Experiential highlighting 4 ff., ff., 9ff. See also: Phenomenal salience Feature Integration Theory 49ff., 4f. Feeling of presence 66, f., , 9ff, FI0ST 9 ff. Gallistel, Randy 69, 9 Gopnik, Alison fn., 9 Gould, James Graded knowledge approach Grush, Rick 4f. Hatfield, Gary 9f., 4 ff. Heck, Richard ff. Image-like Knowledge James, William 4f., 9, Jung, Eva-Maria 9ff.,

9ff. fn., f.

,

ff.



 Index

Kaplan, David 4f. Kentridge, Robert 4f., 44ff. Knowing-how vs. knowing-that Lamme, Victor , f., 9f., Land, Michael 64f. Latour, Bruno f. Le Poidevin, Robin 6 , 94f. Levine, Joseph , , 9 ff. Lewis. David 64fn.

ff., 4

Matthen, Mohan f., , 9f., 6, ff., 4 f., 6. See also: motion-guiding vision Meltzoff, Andrew fn., 9 Millikan, Ruth 94, ff. Motion-guiding vision 9f., 9f., ff. See also: Attention and motion-guiding vision Multiple Object Tracking 9 ff. See also: Attention and multiple object tracking, FI0ST Munakata, Yuko , 9f., f., , f., 9. See also: graded knowledge approach 0adel, Lynn f. 0akayama, Ken 4 f. 0anay, Bence 4fn., 0ewen, Albert fn., 0oë, Alva f., 4 ,

fn., 6, 9fn. 9ff., f., fn. fn., ,

O'Keefe, John f. O'Regan, Kevin f., 4 Object persistence f., 49ff., f., f., , , 6f., f., 6ff., 4 f., 4 ff. Object properties model of object perception ff. Object segmentation processes 4 , , 6, 6, 9, 6, 9f., 4 f., 66, . Optic ataxia f. Peacocke, Christopher , Perry, John 6 fn., 64fn. Phenomenal salience 9ff.

,

, 49f.

– the agentive view of 6 ff. – the cognitive view of 6 ff. Phenomenology – of agentive experience 6 ff., 69f. – of attention see Attention, phenomenology – of demonstrative thought 6 , 6f. – of perception 4 f., ff., 69f. – See also: phenomenal salience, feeling of presence Picture perception f., 6, 9f. Pick, Herbert 96f. Practical abilities , 6, 9 f., 9 ff. Practical knowledge 9 f., f. – and object representation 94, 46f., 4 ff., f., ff. See also: object properties model of object perception – and spatial representation 94ff. – orthodox view of ff., 9, , f., 9 f., 6ff. – versus conceptual knowledge ff., , f., 94ff. – See also: knowing-how vs. knowing-that, graded knowledge approach Pre-attentive perceptual processing ff. – and amodal completion – and feature binding 4f. – See also: object segmentation processes Prefrontal cortex , 9ff., f. Proto-objects , , , ff. Psychological mode ff., 6 ff. Pylyshyn, Zenon , 9 ff. See also: multiple object tracking Quine, W.V.O.

, 4 , 46,

9f.,

Raftopoulos, Athanassios f., 4, f., Recanati, François ff., 66 Rensink, Ronald , , ff., 4 Rougier, 0icolas 9ff. Ryle, Gilbert Saccadic eye movements 64, , Scholl, Brian , , fn. Sensorimotor theory of visual perception f. Shoemaker, Sydney 69 Siegel, Susanna fn.

ff.

Index 

Smith, A.D. f. Sortal concepts ff. Spatial representation 6 ff., 6 ff., 94ff. Spatial significance ff. Speed, Ann ff. Spelke, Elizabeth 4 ff., Stabilization ff., ff. Stazicker, James 4, f., 6ff. Stanley, Jason , Strawson, P.F. f., 4 f., 9f., 6 ff. Subitizing ff. Tacca, Michela f. Tolman, Edward 6 ff. Treisman, Anne see Feature Integration Theory

Type-demonstratives Ventral visual stream Visual form agnosia Visual imagery ff., Watzl, Sebastian 6fn. Wiggins, David ff. Williamson, Tim , Wu, Wayne , ff. Xu, Fei 4 , 4 , Yantis, Stephen 9 ff.

ff. f. 9f., 96

