Human Inference: Strategies and Shortcomings of Social Judgement 0134451309, 9780134451305

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Human Inference: Strategies and Shortcomings o f Social Judgment R ic h a r d

L ee R oss

T H E C E N T U R Y P S Y C H O L O G Y S E R IE S James J . Jenkins Walter Mischel Willard W. Hartup Editors

HUMAN INFERENCE: strategies and shortcom ings of social judgm ent

R ic h a r d N is b e t t University of Michigan

L ee R o ss Stanford University

P R E N T IC E -H A L L , IN C ., Englewood Cliffs, New Jersey 07632

Library of Congress C ataloging in Publication Data

Nisbett, Richard E Human inference. Bibliography: p. Includes indexes. 1. Cognition 2.

Inference (Logic)

I. Ross, Lee, joint author. BF311.N57 153.4'32 ISBN 0-13-445130-9

3. Judgment.

II. Title. 7920945‫־‬

© 1980 by P R E N T IC E -H A L L , IN C ., Englewood Cliffs, N .J. 07632 A ll rights reserved. No part of this book may be reproduced in any form or by any means without permission in writing from the publisher.

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for S U S A N ISA A C S N I S B E T T an d J U D I T H RO SS

contents

preface xi acknowledgements xv

I

Intuitive Strategies of Inference

1 AN IN T R O D U C T IO N T O T H E IN T U IT IV E S C IE N T IS T the fram ework of the book 4 the tools of the intuitive scientist 6 inferential problems and the form al scientific requirements fo r their solution 8 judgm ent and behavior 11 cognitions hot and cold 12 the question of normativeness: the scientist as critic summary 15

13

3

Vili

C ontents

2 J U D G M E N T A L H E U R IS T IC S A N D K N O W L E D G E S T R U C T U R E S 17 the availability heuristic 18 the representativeness heuristic 2 4 knowledge structures: theories and schemas 2 8 inferential adjustment and its limitations 41 summary 4 2

3 A S S IG N IN G W E IG H T S T O D A T A : T H E “ V IV ID N E S S C R I T E R I O N ” 43 factors contributing to the vividness of information 45 explaining the impact o f vivid information 51 redundancy, recruitment, and rehearsal 5 3 inferential effects of pallid data summaries versus vivid cases normative considerations 5 9 summary 62

55

II Inferential Tasks: Normative Principles and Lay Practice 4 C H A R A C T E R IZ IN G T H E D A T U M , S A M P L E , A N D P O P U L A T IO N 65 characterizing the datum: the role o f preconceptions 6 6 characterizing the data sample: availability biases 73 generalizing from instances to populations: representativeness versus sampling theory 77 summary 8 9

5 A S S E S S M E N T O F C O V A R IA T IO N judging covariation from fourfold tables illusory correlation 93

90

91

data-driven and theory-driven judgments o f covariation 9 7 conditioning and covariation detection 101 covariation detection and the perception of personal consistency covariation detection and social adaptation 1 0 9 summary 111

106

C ontents

6

C A U S A L A N A L Y S IS

113

causal analysis and the representativeness heuristic 115 causal analysis and the availability heuristic 1 2 2 misguided parsimony: the “ hydraulic” model of causation 1 2 7 missing causal schemas 1 3 0 intrusion of causal theories into inappropriate domains 135 summary 1 3 7

7 P R E D IC T IO N

139

human intuitions versus actuarial form ulas 1 4 0 base rates versus the representativeness criterion 141 nonregressive prediction tendencies 1 5 0 the dilution effect: producing “ regressive” predictions by exposure to nondiagnostic information 154 circumstances prompting the utilization of base rates in prediction regression phenomena: occasional recognition and chronic miscontrual 1 6 0 summary

156

1 65

8 T H E O R Y M A IN T E N A N C E A N D T H E O R Y C H A N G E

167

old theories and new evidence 1 6 9 sequential processing o f evidence: the primacy effect 1 7 2 belief perseverance after evidential discrediting 175 mechanisms underlying perseverance phenomena 1 7 9 when theories arid beliefs do change 1 88 belief perseverance: the normative question 191 summary 1 9 2

III Inferential Errors: Their Causes, Consequences, and Cures 9 T H E LA Y S C IE N T IS T S E L F -E X A M IN E D characterizing one’s own behavioral dispositions 1 9 6 assessing one’s own emotions and attitudes 1 9 9 causal explanations of one’s own behavior 2 0 2 the basis of causal accounts 2 1 0 the accuracy of causal accounts in everyday life 2 1 6 actors’ unique sources of insight and error 2 2 3 self-knowledge and self-improvement 2 2 6 summary 2 2 6

195

x

C ontents

10 P S Y C H O D Y N A M IC S V E R S U S P S Y C H O L O G IC

228

hot vs. cold cognition: an historical perspective 2 2 8 self-serving biases in causal attributions 231 ethnic prejudice: hearts or minds? 2 3 7 psychoanalysis, psychodynamics, and the representativeness heuristic 2 4 2 summary 2 4 7

11 A SSE SSIN G T H E D A M A G E

249

reconciling inferential triumphs with inferential failures 2 5 0 when intuitive strategies serve us well 254 when ignorance of normative rules may cost us little 2 5 5 inference as a collective enterprise 2 6 6 compensatory errors 2 6 7 inference and behavior 2 6 9 summary 271

12 IM P R O V IN G H U M A N IN F E R E N C E : P O S S IB IL IT IE S A N D L IM IT A T IO N S 2 73 the status of the layperson: pure scientist or applied practitioner? costs and benefits of form al vs. intuitive strategies 2 7 6 programs to improve inferential strategies 2 8 0 overcoming the barriers to change 2 8 6 the role and responsibilities of the social scientist 294 summary 295

references

297

name index subject index

319 327

274

preface

O n e of philosophy's oldest paradoxes is the ap p are n t contradiction betw een the great triu m p h s and the dram atic failures of the h u m a n m ind. T h e sam e organism th at routinely solves inferential problem s too subtle and complex for the m ightiest com puters often m akes errors in the simplest of ju d g m en ts ab o u t everyday events. T h e errors, m oreover, often seem traceable to violations of the sam e inferential rules th at underlie people’s m ost im pressive suecesses. T h e paradox persists in con tem p o rary psychological theory and research. In E u ro p ea n psychology it is the work of P iaget and F reud th a t perhaps provides the best illustration. P iag et’s elegant and provocative theories of cognitive developm ent offer an account of the stages th ro u g h which the initially helpless and ig n o ran t h u m a n in fan t passes on its jo u rn e y to becom e an adult. A nd w hat a piece of work is P ia g e t’s ad u lt— so im pressively arm ed with problem -solving tools and insights into the social and physical w orld. In contrast, the adult h u m an to which F reud introduced us is far less notable for XI

x ii

Preface

m atu re rationality and sophistication than for the vestiges of its infancy. In everyday thought and action, and in the greatest personal and social crises, F re u d ’s adult is governed by unconscious strivings and by prim itive, often irrational inferential processes. C an the P iagetian adult, the m aster of form al operations, be the same organism as the F reudian adult whose m ental life and behavior are so com prom ised by the thought processes an d unfulfilled needs of the infant? T h e sam e paradox is ap p aren t in con tem p o rary N orth A m erican social psychology. M any social psychologists are preoccupied w ith the irratio n al or destructive elem ents of social life— w ith in terg ro u p conflict, w ith the deficiencies of the “ group m in d ,” with social apathy and pathology, with ethnic and racial prejudice, and with biased cognitive processes which reconcile dissonance between action and belief an d which allow illusions of personal m erit to be sustained in the face o f m anifestly contradictory facts. At the sam e tim e, another cadre of scientists explores the rational capacities an d insights that allow people to decipher the m eaning and the causes of social events an d th at bring coherence, harm o n y and predictability to social life. A gain, the reconciliation seems difficult and tenuous. H ow can any creatu re skilled enough to build and m aintain com plex organizations, or sophisticated enough to appreciate the nuances of social intercourse, be foolish enough to m outh racist cliches or spill its lifeblood in pointless wars? T h e position of this book is integrative; it m aintains that people’s inferential failures are cut from the sam e cloth as their inferential successes are. Specifically, we contend that people’s inferential strategies are well ad ap ted to deal with a wide range of problem s, but that these sam e strategies becom e a liability when they are applied beyond that range, p articularly when they are applied to problem s req u irin g some appreciation of the n orm ative principles that help to guide the professional scientist’s m ore form al inferences. W e should w arn the reader that the following pages give relatively m ore atten tio n to shortcom ings, and less to trium phs, than any balanced survey of everyday ju d g m en ts would justify. T his em phasis on erro r follows from m uch the sam e prem ise that leads m any of o u r colleagues to study perceptual illusions o r thinking disorders— the belief that the n atu re of cognitive structures and processes can be revealed by the defects which they produce. T h e hum an adult portrayed in this book does solve difficult problem s, som etim es using deceptively simple strategies first learned in early childhood. At the sam e tim e, this h u m an also m akes egregious ju d g m en ts and ill-considered decisions, h arm in g him self an d others th ro u g h the m isapplication of inform al, but usually helpful strategies and th rough the inability or unw illingness to apply m ore form al inferential principles. W e believe this characterization will prove to be a less paradoxical figure than does the P iagetian po rtrait of a sophisticated paragon who nevertheless som ehow lapses into specific errors inconsistent w ith his general capacities.

Preface

x iii

W e also believe it is also less paradoxical than the F reudian po rtrait of a torm ented creatu re whose errors are largely m otivational, the product of buried needs, wishes, conflicts, trau m as, an d defense m echanism s. Finally, we believe o u r p o rtrait of lay inference helps to tie together a considerable body of w ork in contem porary social psychology. R esearch and theory dealing w ith such classic social psychological phenom ena as attitude change, social influence, and prejudice are presented along w ith m ore recent efforts of the attrib u tio n theorists and th eir kin in the “ cognitive-social” area. O u r intent is to show the continuity betw een those processes underlying intellectual an d social achievem ents and those u n d erlying ju d g m en tal errors and social conflicts. T h e organ izatio n of the book m erits a b rief introduction. In the initial section (chapters 1 to 3), we introduce the reader to the analogy betw een the inferential tasks of the layperson or “ intuitive scientist” and those of the form al scientist, an analogy that figures heavily in the plan of the book. W e then discuss the simplistic but generally helpful cognitive strategies used by the intuitive scientist and show how th eir overapplication or m isapplication can result in m ajo r ju d g m en tal or inferential errors. In the m iddle section (chapters 4 through 8), we deal w ith specific inferential tasks, from the initial collection and coding of the d ata, to the testing and revision of inform al psychological theories, that people perform so im perfectly. T h ro u g h o u t this section we discuss the form al or “ n o rm ativ e” rules of inference of w hich peopie som etim es seem ig n o ran t, rules which they u n d erstan d prim arily in particular narrow an d fam iliar contexts or which they u n d erstan d only in the abstract, w ithout really being able to apply them appropriately and broadly. In the final section (chapters 9 through 12), we first treat two specific issues in m ore detail: the special case of inferences about oneself and o n e’s own behavior (chap ter 9) and the general problem of distinguishing betw een m otivationally based errors and intellectually based ones (chapter 10). T h en , in the last two chapters, we cover the personal and social costs of h u m an inferential shortcom ings (and the factors lim iting such costs), and the possibilities of im proving people’s inferential strategies.

acknowledgments

O u r earliest and most abiding intellectual debt is owed to Stanley S chachter, who was o u r g rad u ate advisor in C o lu m b ia’s social psychology p ro g ram . H e showed us the continuity betw een everyday ju d g m en tal strategies and the form al rules of science. It was from him that we learned that w hen the social scientist is most serious and creative he thinks and talks like a layperson, using fam iliar intuitive strategies and focusing always on the p h enom ena of daily social existence. H e m ade us u n d erstan d that while the form al tools of the scientist are essential, they generally serve the goal of verifying insights, not of p roducing them . O u r second great debt is to Am os T versky. It soon will be ap parent to the reader that this book could not have been w ritten w ithout the foundations laid by D aniel K ah n em an and Amos T versky in their work on ju d g m en tal heuristics. T h a t work alone w ould not have m ade this book possible. O u r conversations with T versky (and on a few delightful occasions with K ah n em a n , as well) were essential to helping us appreciate the im plications of XV

xvi

A cknow ledgm ents

their work for the im m ediate concerns of o u r own research and for the bro ad er concerns of social psychology. In earlier drafts we tried to indicate the specific ideas whose origins could be traced to these inform al conversations. But in order to spare the read er from seeing over and over again in each chapter the refrain, “ W e are indebted to Am os T versky for this id e a ,” we now simply acknowledge, w ith g ratitude, the m agnitude of o u r personal and professional debt. A nother im p o rtan t debt is to two philosophers, Alvin G o ldm an and Stephen Stich. T h eir vigorous criticism helped us to clarify o u r arg u m en ts an d , even m ore im portantly, helped us to recognize this book’s relevance to traditional epistem ological concerns. O u r colleague and academ ic editor, W alter M ischel, also m erits special m ention. H is early encouragem ent, and his unfailingly helpful suggestions for revision, have well justified our intention to publish u n d er his distinguished editorship in the C en tu ry Series. M any other people— too m any to acknow ledge each w ithout risking an em barrassing om ission— have generously donated their tim e to com m enting on earlier versions of the book or on o u r earlier research reports. Som e of these inform al reviewers, how ever, have exerted such an im pact on so m any chapters or saved us from such serious erro rs, that their help m ust be acknow ledged publicly. T his list of generous colleagues includes R o b ert Abelson, T eresa A m abile, D aryl Bern, E ugene Borgida, Philip B rickm an, G ordon Bower, R obyn Dawes, Phoebe Ellsworth, P atricia G u rin , T o ry H iggins, D ennis Jen n in g s, E dw ard E. Jo n es, H aro ld Kelley, D avid K ran tz, R onald Lem ley, R ichard L em pert, M ark L epper, H azel M ark u s, Shelley T aylor, and T im o th y W ilson. We also are deeply indebted to the dozens of fine graduate students and to our stim ulating colleagues at M ichigan and Stanford who have helped us over the last several years to form ulate and clarify the ideas presented in this book. T h e au th o rs’ research reported in this book was greatly facilitated by generous research support from the N atio n al Science F oundation and the N ational Institute of M en tal H ealth. No book reaches publication w ithout m uch p ainstaking prelim in ary work, including typing and retyping endless drafts, countless hours proofreading and reference finding, and scores of tactful suggestions about errors in g ram m ar and incom prehensible sentences. T h e contrib u tio n s o f J o y D avis, S haron Frey, Lois G ovaere, and Shelagh T ow son are gratefully acknow ledged. We are sim ilarly indebted to M arg aret Y am ashita for her superb jo b in copy editing an d to C harles Lord for his painstaking p rep aratio n of the subject index. Finally, we wish to express our g ratitude, and o u r love, to those who collaborate not in our w riting or in our research, b u t in our lives: T o Susan and Ju d y , and to our children, M atthew N isbett and J o sh u a , T im othy an d Rebecca Ross.

part I

INTUITIVE STRATEGIES OF INFERENCE

1 an introduction to the intuitive scientist

The logic of science is also that of business and life, /

John Stuart Mill.

T his book is about h u m an inference and h u m an erro r. It portrays people as intuitive scientists who are gifted and generally successful, b u t whose attem pts to u n d erstan d , predict, and control events in the social sphere are seriously com prom ised by specific inferential shortcom ings. In p art, these shortcom ings reflect people’s failure to use the norm ative principles and inferential tools th at guide form al scientific in q u iry . T hey also reflect people’s readiness to apply m ore sim plistic inferential strategies beyond their app ro p riate lim its. T h e book will d o cu m en t both un d eru tilizatio n of norm atively app ro p riate strategies and overutilization of m ore prim itive intuitive strategies. P art 1 describes some of the intuitive strategies and illustrates their overuse. P art 2 draw s an analogy betw een the inferential tasks of the form al scientist and those of the layperson and docum ents the lay p erso n ’s errors m ade by failing to em ploy norm atively correct strategies in daily life ju d g m en ts. P art 3 ex3

4

H um an Inference

am ines the origins of inferential failings, the costs o f these failings, an d the possibility of im proving people’s inferential strategies.

TH E FRAMEWORK OF T H E BOOK

In m any ways, this book represents a retu rn to a curren tly unfashionable tradition in W estern th o u g h t— the epistem ological trad itio n of sim ultaneous concern w ith psychological description and with n o rm ativ e prescription. T h e early epistem ologists, for exam ple, Bacon, D escartes, Locke, and Spinoza, were as m uch psychologists as philosophers. M u ch of th eir work was concerned with describing, in the form o f em pirically testable propositions, the structures and processes o f h u m an thought. T hese descriptions then w ere used as d ep artu re points for criticism and for proposing m ore ap p ro p ria te an d effective habits of thought. T h is trad itio n of equal concern w ith description and prescription was continued in the work of such later philosophers as H u m e, K an t, an d Mill. A round the tu rn of the cen tu ry , philosophers b eg an to ab an d o n d escrip ‫־‬ tive w ork, leaving this to the new discipline of psychology, w hich was developing em pirical m ethods for describing thought processes. T h ere was a new division of labor, in which psychologists focused on the essentially em pirical task of description and philosophers focused on the n o rm ativ e tasks of criticism and prescription. T h e p redom inantly n o rm ativ e em phasis is already evident in the work of such early tw entieth-century epistem ologists as R ussell, C a rn a p , an d Popper. Lately, some epistem ologists, notably Alvin G oldm an (1978, 1979), have begun to recognize th at n o rm ative issues are illum inated by the recent descriptive work of cognitive psychologists and have devoted them selves to learning this work. T h e literatu re of cognitive psychology presents evidence of the sorts of m ental processes th at people use for p articu lar problem s an d provides strong hints of the lim its of h u m a n cognitive capacities. G o ld m an (1978) has argued that it m akes little sense for philosophers to ignore such w ork an d to propose cognitive procedures w hich people m ay be incapable of actually using, an d he an d o ther epistem ologists have recognized th at it is sim ilarly pointless to criticize cognitive procedures th at people do not actually use. T h e concerns of this book are com plem entary. R ecent descriptive work by cognitive psychologists an d by social psychologists concerned w ith inference has u n earth ed cognitive procedures ran g in g from the dubiously effective to the patently in adequate. It m akes little sense sim ply to describe such procedures and m ove on; they cry out for criticism . In d eed , som e psychologists w orking in this trad itio n have assum ed the critic’s role. Beginning with classic work on decision m aking (E dw ards 1954) and on clinical

A n Introduction to the Intuitive Scientist

5

versus statistical prediction by M eehl (1955), psychologists in the ju d g m en t an d decision-m aking trad itio n s have allowed th eir em pirical work to be guided by norm ativ e m odels and have com pared both the layperson and the scientist to form al canons of inference. Investigators w orking in this new er, critical trad itio n include H e rb ert Sim on and his collaborators, D aniel K ah n em a n and A m os T v ersk y , and the O regon D ecision R esearch G ro u p of P aul Slovic, S arah L ichtenstein, R obin D aw es, an d B aruch Fischhoff. T his book grows out o f this critical trad itio n an d draw s heavily on the ideas and research o f these investigators. A n equally im p o rtan t influence on the book com es from the cognitive trad itio n w ithin social psychology. T his trad itio n was founded in A m erica by the neo-G estaltist K u rt Lew in. L ew in ’s chief concern was with the cognitive structures and processes th a t produce actions in the social sphere. H is rep resen tatio n of these structures and processes was quasi-geom etrical, stem m ing perhaps from G estalt psychology’s spatial perception concerns. L ew in ’s representational m ode depicting the “ life space” of the individual by goal regions, b arrie rs, forces, and vectors did not prove useful to investigators w orking in the trad itio n he established an d , for the m ost p a rt, has been abandoned. It has been replaced by m ore purely verbal concepts and relations such as those proposed by Fritz H eid er in his classic book The Psychology of Interpersonal Relations. H eid er proposed a very small list of subject term s (for exam ple, person, other, life space) an d predicate relations (for exam ple, cany ought, tries, suffers, benefits, harms, causes, wants) to describe the phenom enology o f person perception an d the processes o f interpersonal relations. H eid er also introduced the notion o f causal attrib u tio n as a fundam ental process underly in g m uch of social perception an d action. H aro ld Kelley (1967), building on J o n e s ’s and D av is’s (1965) earlier efforts, form alized H e id e r’s conceptions of causal inference an d drew the parallel betw een the lay p erso n ’s m ethods o f analysis and the scientist’s. K elley’s form ulation o f attrib u tio n theory bro u g h t the study of causal inference to the center stage of social psychology. W h at Kelley proposed, essentially, is that the layperson m akes causal inferences using criteria analogous to those used by the train ed social scientist. T h e layperson notes the covariation betw een p articu lar “ effects” (social acts and outcom es) and potential “ causes” (the presence or absence of specific actors and particu lar features of the situation). From such observations, the layperson arrives at roughly the sam e conclusions th at the academ ically tu to red scientist would reach th ro u g h m ore form al statistical analyses an d m ore rigorously applied logical principles. F or exam ple, Sally infers th at the “ cau se” o f J a n e ’s enthusiastic reco m m en d atio n of C hez P aris was the quality o f the restau ran t rath e r than J a n e ’s u n d iscrim in atin g palate, ulterio r m otives, or chance, to the extent that certain essentially statistical criteria are m et: Specifically, the recom m endation should show consistency (Jan e m akes the sam e reco m m en d atio n on m any

6

H um an Inference

occasions and in m any contexts), distinctiveness (Jan e does not m ake sim ilarly enthusiastic recom m endations of all restau ran ts), and consensus (o th er p atro n s of C hez Paris seem to share J a n e ’s enthusiasm ). T h e layperson, in trad itio n al attrib u tio n theory, is capable of applying psychological, as well as logical an d statistical insights. T h e layperson seems to know m uch about the situational pressures an d constraints that influence h u m an behavior, an d causal attrib u tio n s reflect such know ledge. T h u s, a dollar given to a p an h an d ler is apt to be attrib u ted to the g iv er’s generosity only to the extent that the situational context is free of the usual reasons for eliciting such gifts from “ people in g e n e ra l.” If the p a n h a n d le r’s d em ean o r suggested that a less generous “ gift” m ight b rin g insults or physical abuse, o r if the p a n h a n d le r’s plight seem ed p articularly sad, the intuitive psychologist would be far less likely to assum e that the giver is particu larly generous or to assign a critical causal role to such “ g en ero sity .” Kelley, in his 1967 article and in subsequent co n trib u tio n s (1972, 1973), cited m any studies showing that lay causal attrib u tio n s do correspond to norm ative standards of inference. Subsequent investigators (notably M cA rth u r, 1972, 1976) also supported this view. K elley’s form ulation of attrib u tio n theory and his parallel betw een the inferential tasks of the layperson and those of the scientist provided the impetus for the present book. Each of us has done research on causal attrib u tio n processes. But th ro u g h th a t w ork we have becom e increasingly m ore impressed with the evidence of p eople’s d ep artu res from n o rm ativ e stan d ard s of inference and less im pressed w ith the evidence of th eir adherence to them (Ross, 1977a). T his concern has been au g m en ted by o u r contact w ith researchers, most notably Amos T versky and D aniel K ah n em an , who are concerned w ith inform al ju d g m en t. T h e ir w ork has revealed p ro fo u n d , system atic, and fundam ental errors in ju d g m en ts an d inferences. T hese errors are the m ajor concerns of this book. W e will consider the ways in which these errors deviate from n o rm ative standards of logical and scientific inference, the origins and un d erly in g causes of these errors, an d the im plications of these errors both for social psychological theory and for the problem s of everyday social life.

T H E T O O L S O F T H E I N T U I T I V E S C IE N T IS T

T his book contends that the seeds of inferential failure are sown w ith the sam e im plem ents th at produce the intuitive scientist’s m ore typical successes. T hese intuitive im plem ents are of two b ro ad types— “ know ledge stru c tu re s” which allow the individual to define an d in terp ret the d ata of physical and

An Introduction to the Intuitive Scientist

7

social life and ‘‘ju d g m en tal h eu ristics” which reduce com plex inferential tasks to sim ple ju d g m en tal operations. Few, if any, stim uli are approached for the first tim e by the adult. In ‫־‬ stead, they are processed th ro u g h preexisting systems of schem atized and abstracted know ledge— beliefs, theories, propositions, and schem as. T hese know ledge structu res label and categorize objects and events quickly and, for the m ost p art, accurately. T h ey also define a set of expectations about objects and events and suggest ap p ro p riate responses to them . A price is paid for this m ental econom y, how ever. T h e knowledge structures them selves are not in ‫־‬ fallible guides to the n atu re of physical or social reality. Some beliefs, theories, and schem as are relatively poor and inaccurate representations of the external w orld. M ore d angerous, objects and events are not always labeled accurately and som etim es are processed th ro u g h entirely in ap propriate know ledge structures. W ithout these structures stored in m em ory, life would be a buzzing confusion, b u t their clarity is helpful only in proportion to their validity and to the accuracy w ith which they are applied to the data at hand. Besides know ledge structures, people also use a few simple ju d g m en tal heuristics. T hese cognitive strategies, or rules of th u m b , are the lay p erso n ’s tools for solving a variety o f inferential tasks. T h e two heuristics on which K ah n em an and T versky focused are the representativeness heuristic and the availability heuristic. T h e representativeness heuristic allows the individual to reduce m any in ‫־‬ ferential tasks to w hat are essentially simple sim ilarity ju d g m en ts. An object is assigned to one conceptual category rath e r than to an o th er according to the extent to which its principal features represent or resem ble one category m ore than an o th er. A botanist assigns a plant to one species rath er than an o th er by using this ju d g m en tal strategy. T h e plant is categorized as belonging to the species that its principal features m ost nearly resem ble. T h e problem with the heuristic is that it is som etim es used as the only ju d g m en tal strategy w hen it cannot alone provide an accurate ju d g m e n t. W hen the know n features of an object can n o t categorize it definitely, statistical considerations becom e im p o r‫־‬ tant to correct categorization. In p articu lar, the relative frequency of the categories in the population u n d er consideration becom es the norm atively ap ‫־‬ pro p riate guide to categorization to the extent th at the know n features o f the object are am biguous guides to categorization. T h e work o f K ah n em an and T versky (1973) shows th at people have little u n d erstan d in g o f these statistical considerations or o f how to com bine the statistical considerations w ith representativeness considerations. T h e availability heuristic is used w hen ju d g in g frequency, probability, an d even causality. O bjects o r events are ju d g e d as frequent, probable, or causally efficacious to the extent th at they are readily “ available” in m em ory. T h e heuristic is a fallible guide for such ju d g m en ts because m any factors

8

H um an Inference

besides actual frequency, statistical probability, o r tru e causal efficacy affect the m em orial availability of objects an d events. A final intuitive strategy involves w eighting the relevance of o n e ’s data. W e argue that people effectively assign inferential weight to physical an d social data in proportion to the d a ta ’s salience an d vividness. In fo rm atio n is heeded, processed, stored, and retrieved in pro p o rtio n to its sensory, cognitive, and affective salience. By default, m ore vivid in fo rm atio n is m ore likely to enter inferential processes than is less vivid inform ation. T h is strategy of evidential w eighting is dangerous because the vividness of inform ation is norm ally related only obliquely at best to its tru e value as evidence. T hus, the layperson approaches the inferential tasks o f everyday life arm ed w ith know ledge and w ith strategies th a t, for all th eir general helpfulness and efficiency, have m any flaws. T hese flaws are co m p o u n d ed by the knowledge and the strategies th at the layperson does not possess, or at any rate fails to use in m any inferential tasks to w hich they are essential.

INFERENTIAL PROBLEMS AND THE FORMAL SCIENTIFIC REQUIREM ENTS FOR T H E IR SOLUTION

T h e form al inferential rule system followed by professional scientists is the stan d ard against which the layperson is com pared th ro u g h o u t this book. W e believe that this com parison is not forced or artificial, nor is it entirely un* fair to the layperson. M an y of the inferential tasks th at confront the layperson are directly analogous to those th at confront the scientist. In ad d itio n , the layperson’s inferential failings, we believe, often can be traced directly to ignorance of the form al scientific req u irem en ts for solving these inferential problem s. It will be useful, therefore, to describe som e o f the inferential tasks confronting both the form al an d the lay scientist. T h e most basic inferential tasks are descriptive. T h e form al scientist m ust be able to characterize and describe accurately the individual datum— object, o r event. W hen, as is usually the case, there is m ore th an one object o r event to be considered, the scientist m ust accurately characterize the sample o f d ata, a task which entails several, m ainly arithm etic operations. O ften the sam ple of objects or events is treated as the evidential base for generalizing to some population of objects or events, a task w hich entails several statistical as well as arithm etic operations. M an y tasks require m ore than the m ere description o f single events (or sam ples or populations of a single type of event) an d are concerned p rim arily with relationships betw een different types of events. T h e scientist often needs

A n Introduction to the Intuitive Scientist

9

to observe covariation betw een events an d to m easure the m agnitude of the covariation in term s of some defined criterion. If possible, principles or theories capable of causally explaining the covariation are form ulated. T he observed covariation and the postulated causal explanations then are used as the basis for predicting future events. For the form al scientist, all three tasks are governed by fixed statistical an d logical principles. Finally, the form al scientist adheres to a set of general rules for theory testing, w hich operate at every stage of the in quiry. T h ere are rules for testing w hether a given ch aracterizatio n of the d atu m , sam ple, or population is correct, w hether events covary as believed, w hether causal explanations are adeq u ate, and w hether predictions are valid guides to future events. W e a rg u e that, in the context of daily life, the intuitive scientist is prone to m ake certain errors in solving the analogous inferential problem s. These errors do not result from any inability to com prehend the principles of scientific inference. In d eed , alm ost all o f the m ost frequently violated p rin ‫־‬ ciples can be described on some level of abstraction and can be illustrated in some p articu lar context th a t w ould be readily understood and accepted by any bright adolescent. T h e intuitive scientist, m oreover, does readily apply m any of the principles u n d e r certain circum stances— for exam ple, when an ap p ro p riate ‘*problem -solving set” is established and w hen the data and p ro ‫־‬ blem form at p ro m p t ap p ro p riate strategies and discourage in ap p ro p riate ones. C onversely, even the form al scientist is susceptible to m any o f the fail‫־‬ ings we shall describe, in everyday life an d occasionally even in scientific endeavors. W e will preview the intuitive sc ie n tists shortcom ings, each of which will be exam ined in later chapters. D e s c r ip t io n . In ch aracterizin g the single datum, the intuitive scientist often is m isled by p rio r theories of the object or event in question. Preexisting know ledge stru ctu res influence u nduly, and often w ithout the in d iv id u al’s aw areness, the ch aracterization of a given event. In characterizing samples, the lay scientist usually is at the m ercy o f the sam ple of events that can be retrieved from m em ory. T his w ould present little difficulty if the only d eter‫־‬ m in an t of the m em orability o f events was their relative frequency. T his clear‫־‬ ly is not the case, how ever, since salience, retrievability, and o th er factors un related to tru e frequency, often influence the m ake-up of the sam ple of events that the individual can recall. Such biases in the ^ re a d -o u t” will create distortions in ch aracterizing the sam ple. W hen the individual attem pts to generalize from the characteristics o f the sam ple to those of the population, two considerations becom e p a ra m o u n t— the size o f the sam ple and its freedom from bias. T h e evidence indicates, how ever, that people have little u n d erstan ‫־‬ ding of the im portance of eith er consideration. T h ey seem to have little conception of the relative stability to be expected of the characteristics of a large set of observations or, conversely, of the instability and unreliability of the characteristics displayed in a small set of observations. M ore seriously, people

IO

H um an Inference

seem to have little conception of the dam age done by sam ple bias. T h ey seem to be alm ost as willing to generalize from sam ples know n to be biased in crucial p aram eters as to generalize from sam ples know n to be u nbiased. D etection of c o v a r ia t io n . T h ere is no assum ption as critical to contem porary attrib u tio n theory (or to any theory th at assum es the lay p erso n ’s general adequacy as an intuitive scientist) as the assum ption th at people can detect covariation am ong events, estim ate its m ag n itu d e from som e satisfactory m etric, and draw ap p ro p riate inferences based on such estim ates. T h ere is m o u n tin g evidence th at people are extrem ely poor at perform ing such covariation assessm ent tasks. In p articu lar, it appears th at a priori theories or expectations m ay be m ore im p o rtan t to the perception o f covariation th an are the actually observed data configurations. T h a t is, if the layperson has a plausible theory that predicts covariation betw een two events, then a substantial degree of covariation will be perceived, even if it is present only to a very slight degree or even if it is totally absent. C onversely, even pow erful em* pirical relationships are apt not to be detected or to be radically underestim ated if the layperson is not led to expect such a covariation. C ausal in fe r e n c e . W hen people have m an ag ed a detect a p attern of covariation, they still m ay fail to analyze correctly the possible causes of the covariation. In some instances, strong p rio r theories of causality m ay override the im plications of the covariation p attern . In oth er instances, peoples’ inferences about causality ap p ear alm ost a rb itrary or capricious because they are so heavily influenced by the perceptual salience of p articu lar causal candidates. In still other instances, causal “ schem as” or analytic strategies appropriate in some dom ains m ay “ in tru d e ” into dom ains to which they are inappropriate, causing m ore ap p ro p riate and helpful schem as to be overlooked. P r e d ic t io n . Even w hen people have recognized the tru e degree of covariation in a data set and have m ade correct causal inferences ab o u t the basis for the covariation, they m ay m ake norm atively in ap p ro p riate predictions about future cases. M ost critically, people ap p ear to have little concept of the relevance of population base rates in general an d regression p h en o m en a in particular. W hen required to predict the outcom e of an event, people tend to ignore the base rates, o r relative frequencies of the outcom e possibilities. W hen dealing with p aram etric observations, people tend to m ake “ nonregressive” predictions that* would be ju stified only if the em pirical covariation were far greater th an is usually the case in the social d o m ain. T heory t e st in g . People have few of the form al scientist’s skeptical or disconfirm atory skills. O nce form ulated or adopted, theories and beliefs ten d to persist, despite an array of evidence th a t should invalidate or even reverse them . W hen “ testin g ” theories, the layperson seems to rem em b er p rim arily confirm atory evidence an d to ignore potentially d isconfirm atory evidence. W hen confronted forcibly by disconfirm atory evidence, people a p p ea r to behave as if they believed th a t “ the exception proves the r u le .”

JU D G M E N T AND BEH AVIOR

P art 2 of the book docum ents errors in each of the ju d g m en tal dom ains ju st described. T h e read er not fam iliar w ith the research on ju d g m en t and inference m ight w onder w hether people’s behavior reflects the type of ju d g m en tal errors we discuss. W e hasten to assure such readers that there is substantial evidence show ing th at b ehavior often reflects, indeed som etim es am plifies, these ju d g m e n ta l errors. T h e a ttrib u tio n literatu re shows th at people do not m erely verbalize dubiously correct causal explanations b u t express them behaviorally both inside and outside the lab o rato ry (w hen they often are unaw are that they are subjects in an experim ent). B ehaviors which have been shown to reflect p rio r causal attrib u tio n s include insom niacs’ sleeplessness, stu tterers’ verbal productions, nursery-school ch ild ren ’s willingness to cheat at gam es an d college stu d en ts’ w illingness to cheat on exam inations, ad u lts’, adolescents’, and ch ild ren ’s tim e spent w orking on and playing at various activities, elem entary school stu d en ts’ litterin g o f school grounds, and housew ives’ willingness to place an ugly billboard advertising n atu ral beauty on their lawns! In the literatu re on ju d g m e n t and decision m aking, the connection is even stronger since the ju d g m en ts studied are themselves typically behaviors of very g reat im portance: ju d g m en ts by clinicians o f the degree of p atien ts’ m ental illness, ju d g m en ts by social w orkers of a clien t’s inclination tow ard child abuse, ju d g m en ts by parole officers of convicts’ likelihood of recidivism , ju d g m e n ts by faculty adm issions com m ittees of acceptance of applicants for g raduate school, and ju d g m en ts by stockbrokers o f the advisability of purchasing p articu la r stocks. W e do not em phasize these real-wo rid, behavioral effects in o u r review of the literatu re because we believe the m ain points are not in dispute: P eo p le’s ju d g m en ts often affect th eir behavior, an d both th eir ju d g m en ts and their behavior reflect inferential errors outside the laboratory as well as in it. W e also say little ab o u t precisely how people’s ju d g m en ts affect their behavior. T his is n eith er an oversight n o r a deliberate choice. W e simply acknow ledge th a t we share o u r field’s inability to bridge the gap betw een cognition and behavior, a gap that in o u r opinion is the m ost serious failing of m odern cognitive psychology. T h e problem was perhaps first noted by E. R . G u th rie in his fam ous gibe at E. C . T o lm an , who m ay be considered the founder of m o d ern cognitive psychology. Professor T o lm a n ’s rat, G u th rie jo k ed , can never reach the goal at the end of the m aze but rath er, is left at the start box— w ith its hypotheses, theories, and expectations— ‘‘b u ried deep in th o u g h t.” C ognitive psychologists had m ade so little progress in treatin g behavioral m atters th a t, decades later, D aryl Bern was obliged to adm it that 11

12

H um an Inference

cognitive theories, including his own self-perception theory, “ rem ain m u te about any phenom enon in which the noncognitive response classes play the dependent variable role; as dep en d en t variables such response classes are extra-theoretical. . . . H ow do attrib u tio n al m odels account for noncognitive response classes? T hey do n o t” (1974, p. 217). T h ere is surely no m ore im p o rtan t task for cognitive psychologists than to b rin g these noncognitive response classes u n d e r their theoretical urnbrella— to provide a way of explaining the circum stances u n d er w hich, the m an n er in which and the degree to w hich, p articu lar ju d g m en ts influence particular behavior. H ad we ourselves been able to m ake even ten tativ e inroads into these problem s, we w ould have done so.

COGNITIONS HOT AND COLD

Since this book is about inferential errors, the authors are b o u n d to be asked w hether such errors are not also the products of people’s motivational and emotional m ake-up. W e should confess from the outset the prejudice in o u r view point. W e proceed from the w orking hypothesis th at inferential and ju d g m en tal errors arise p rim arily from n o n m o tiv atio n al— perceptual and cognitive— sources. Such erro rs, we contend, are alm ost inevitable products of h u m an inform ation-processing strategies. In o rd in ary social experience, people often look for the w rong d ata, often see the w rong d ata, often retain the w rong data, often weight the data im properly, often fail to ask the correct questions of the d ata, an d often m ake the w rong inferences on the basis of their u n d erstan d in g of the data. W ith so m any errors on the cognitive side, it is often red u n d an t an d u n p arsim onious to look also for m otivational erro rs. W e argue that m any ph en o m en a generally reg ard ed as m otivational (for exam ple, self-serving perceptions and attrib u tio n s, ethnocentric beliefs, and m any types of h u m a n conflict), can be u n d ersto o d b etter as p roducts of relatively passionless inform ation-processing erro rs th an o f deep-seated m otivational forces. W e have no wish, how ever, to deny th at m otives and em otions can influence h u m an inference or to assert that all h u m a n follies can be explained by program erro r. Indeed, the perceptual and cognitive biases that we have described often operate on social d ata biased already by m o tivational an d em otional factors. O n e ’s choice of friends, residence, occupation, news m edia, topics for reading and conversation, and perhaps even the social theories and theorists to whom we expose ourselves, all show the im pact of such factors. T o the extent that m otives dictate social beh av io r, which in tu rn influences o n e ’s samples of inform ation about the w orld, there is am ple opp o rtu n ity for social inferences to be distorted by needs an d wishes. O u r w ork­

A n Introduction to the Intuitive Scientist

13

ing assum ption, therefore, is sim ply th at self-serving m otivational factors need not be in tro d u ced to explain m ost of the fundam ental inferential or judgm ental biases discussed in this book. In fact, as we shall see, the erroneous ju d g m en ts, predictions, and causal assessm ents reached by the intuitive psychologist— far from being self-serving— often undermine self-esteem and limit the in d iv id u al’s capacity to satisfy personal needs.

T H E Q U E ST IO N OF NORM ATIVENESS: T H E SC IE N T IST AS CRITIC

Since this book is about inferential erro r, the question b ound to arise in the m inds o f m any readers is ju st how one knows that certain inferences are ‘4e rro n e o u s ,” or, to tu rn the question a ro u n d , how one knows that a given inferential strategy is “ co rrect” o r norm atively ap p ro p riate. O u r answ er to this question is straightforw ard: W e follow conventional practice by using the term “ n o rm a tiv e ” to describe the use of a rule when there is a consensus am ong form al scientists th at the rule is ap p ro p riate for the p articu lar problem (cf. Stich & N isbett, 1979). Some of the problem s th at we discuss, however, are relatively novel, an d such “ consensus” as exists is confined to the authors and the few colleagues with whom we have discussed the problem s. In some cases, the term “ n o rm ativ e” m eans “ w hat the authors (and at least some o th er people) take to be the ap p ro p riate strateg y .” In these cases, the ju d g m e n t th at a given strategy is norm atively ap p ro p riate is a tentative one th at ultim ately m ust be upheld or reversed by the court of inform ed opinion. W e do not d o u b t th at m any o f our own cu rren t ju d g m en ts about w hat is norm atively ap p ro p riate will be overtu rn ed . In w riting the book, we have changed o u r m inds ab o u t too m any n o rm ative questions too often to be u n d er any illusions o f the d u rability o f these ju d g m en ts. M oreover, we have becom e increasingly aw are of the difficulty o f defining w hat is “ n o rm ativ e” w hen one m oves beyond the relatively simple question of how to solve correctly some p articu la r problem . “ N orm atively ap p ro p ria te ” strategies for the solution of some problem s are extrem ely tim e consum ing and expensive. It m ay be clear w hat m ust be done if one wishes a correct answ er to such problem s, b u t som etim es it m ay be even clearer that the correct solution is not w orth the effort. T h is gives rise to m ore im p o rtan t questions of norm ativeness which are not fundam entally em pirical in n atu re: H ow m uch effort, for w hat kinds of problem s, should be expended to o btain a correct solution? W e have becom e excited by such norm ative questions and are pleased that o u r book highlights them . W e have not been able to m ake m uch progress tow ard their solution, how ever, and do not retu rn to them until the final

14

H um an Inference

chapters, in which they are discussed only briefly. It is our hope th at others, particularly philosophers who are m ore com fortable w ith such questions, will be m otivated to pursue them . W e wish to say som ething else about the role of scientist as critic. W e know from past experience in p resenting this m aterial th at some people are offended by the spectacle of th eir fellow h u m an beings caught in inferential traps designed by sm arter-th an -th o u psychologists. It m ay be helpful in forestalling this u n d erstan d ab le response to em phasize th at this book was w ritten in a spirit of genuine hum ility. W e have found that our richest source of d ata dem on stratin g h u m an inferential failings com es not from the u n d erg rad u ates in our experim ents or classroom s b u t from ourselves and o u r friends, most of whom are train ed social scientists. C onsistent w ith this belief, we have m ixed personal anecdotes w ith form al d ata th ro u g h o u t the book. For us, and we trust for the reader as well, these anecdotes often will prove m ore disconcerting than the form al em pirical work. A second reason for o u r hum ility is th at we rem ain enorm ously impressed with the pow er and accom plishm ents of the h u m an m ind. In w riting this book, we began to feel that w orkers in h u m a n inference are now in a position akin to that of investigators of h u m an perception. P erception researchers have shown that in spite of, and largely because of, peo p le’s exquisite perceptual capacities, they are subject to certain perceptual illusions. N o serious scientist, how ever, is led by such d em onstrations to conclude that the perceptual system u n d er study is inherently faulty. Sim ilarly, we conclude from o u r own research th at we are observing not an in h erently faulty cognitive app aratu s but rath er, one th at m anifests certain explicable flaws. In d eed , in h u m an inference as in perception, we suspect that m any of peo p le’s failings will prove to be closely related to, or even an u n avoidable cost of, th eir greatest strengths. O u r respect for intuitive inferences, how ever, should not obscure o u r conviction that there is considerable room for im provem ent. T h a t im provem ent in inferential abilities can result from form al train in g , especially train ing in statistics, is readily docum ented. T h e general question of prophylaxis and cure for inferential shortcom ings is the topic of o u r final chapter. W e wish, finally, to address a quite different kind of read er. In o u r experience, some people respond to the m aterial in this book w ith the attitu d e “ W ell, I always knew m ost people were stupid, an d this ju s t proves it .” W e hope to show that this com forting attitu de is not tenable. W e hold a co n trary view, expressed by A m os T versky, th at there is no inferential failure th at can be dem onstrated with u n train ed u n d erg rad u ates th at can n o t also (at least with a little ingenuity) be d em onstrated in som ew hat m ore subtle form in the highly trained scientist. For any readers who m ay be inclined to exem pt them selves from the inferential failings cited in this book, we p resen t the following thoug h t-ex p erim en t, which will serve as a touchstone for us at several points.

An Introduction to the Intuitive Scientist

15

Let us suppose that you wish to buy a new car an d have decided that on grounds of econom y an d longevity you w ant to purchase one of those solid, stalw art, m iddle-class Swedish cars— either a Volvo o r a Saab. As a p ru d en t an d sensible b u y er, you go to Consumer Reports, which inform s you that the consensus of their experts is that the Volvo is m echanically superior, an d the consensus of the readership is that the Volvo has the b etter rep air record. A rm ed w ith this in form ation, you decide to go and strike a b arg ain with the Volvo dealer before the week is out. In the interim , how ever, you go to a cocktail p arty w here you announce this intention to an acq u ain tan ce. H e reacts with disbelief and alarm : “ A Volvo! Y o u ’ve got to be kidding. M y brother-in-law had a Volvo. First, that fancy fuel injection co m p u ter thing w ent out. 250 bucks. N ext he started having trouble w ith the rear end. H a d to replace it. T h en the transm ission an d the clutch. Finally sold it in three years for ju n k .” (N isbett, B orgida, C ran d all, & R eed 1976, p. 129)

T h e logical status of the cocktail party inform ation is that the n u m b er of V olvo-ow ners has increased from several h u n d red to several h u n d red and one, an d that the frequency-of-repair record perhaps should be changed by an iota on a few dim ensions. W e trust that readers will recognize that their own response to the enco u n ter w ould not be so trivial a statistical adjustm ent or be the calm observation th at ‘‘every now and again one does sam ple from the tails of the d is trib u tio n .” W e hope that the following chapters offer several such glim pses of the shortcom ings of h u m a n inference in everyday life, and we are confident that the re a d e r’s response to some of these portraits will be a sheepish grin.

SUM M ARY

T h e book traces the source of m any inferential errors to two tendencies: the overutilization of certain generally valid, intuitive, inferential strategies an d the u n deru tilizatio n of certain form al, logical, an d statistical, strategies. T h e intuitive strategies include the application of preexisting “ knowledge stru c tu re s” — schem as, beliefs, an d theories— and the utilization of the ‘4rep resen tativ en ess” an d ‘‘av ailability” heuristics. T h e tasks of lay inference are com pared with the tasks of the form al scientist, including ch aracterization of events, sam ples and populations; assessm ents of covariation, causal analysis, prediction, and theory testing. T h e la y p erso n ’s characterizatio n s of events often are unduly influenced by p rio r beliefs or know ledge structures. C h aracterizatio n of samples is d istorted by

16

H um an Inference

the differential “ availability” in experience and m em ory of various events. C haracterization of the population is com prom ised by ignorance of statistical considerations, chiefly those of sam ple size and sam ple bias. C o v ariatio n assessm ent is overly influenced by prior theories of expected covariation and is insufficiently influenced by actual d ata configurations. C ausal analysis suffers from a sim ilar overutilization of p rio r theories and from overreliance on the sheer conspicuousness of potential causal candidates. People have little knowledge of the regression considerations underly in g prediction tasks and substitute simple sim ilarity or representativeness ju d g m en ts. Finally, people have little appreciation of strategies for disconfirm ation of theories and often persist in adhering to a theory w hen the n u m b er of exceptions to the theory exceeds the nu m b er of confirm ations. It is argued that people’s behavior often reflects the errors ap p aren t in their verbal ju d g m en ts and th at the erroneous ju d g m en ts are best u n derstood as cognitive failings rath er than as m otivational ones. T h e book raises, b u t m akes little attem pt to answ er, im p o rtan t “ n o rm a tiv e ” questions.

2 judgmental heuristics and knowledge structures

The most characteristic thing about mental life, over and beyond the fact that one apprehends the events of the world around one, Is that one constantly goes beyond the information given. Jerome Bruner:

T h e perceiver, as B ru n er (1957) recognized, is not sim ply a dutiful clerk who passively registers item s of inform ation. R ath er, the perceiver is an active in terp reter, one who resolves am biguities, m akes educated guesses about events that cannot be observed directly, and forms inferences about associations and causal relations. In this chapter we explore the strategies that perm it and encourage the perceiver to “ go beyond the inform ation g iv e n /' that is, to venture beyond the m ost im m ediate im plications of the data. We sketch some of the “ know ledge stru c tu re s" applied to u n d erstan d in g the world. T hese range from broad propositional theories about people in general to m ore schem atic representations of objects, events, and actors. These structures house the p erso n 's generic knowledge and preconceptions about the world and provide the basis for quick, coherent, but occasionally erroneous in terp retatio n s of new experience. Before discussing these stru ctu res, we will introduce the reader to the “ availability h e u ristic " and the “ representativeness h e u ris tic " — two simple 17

18

H um an Inference

ju d g m en tal strategies on which people seem to rely, and by w hich they som etim es are misled, in a variety o f inferential tasks. In so doing, the chapter introduces the reader to a set of ex trao rd in arily im p o rtan t contrib u tions by D aniel K ah n em an and Am os T versky (1972, 1973, in press; T versky & K ah n em an , 1971, 1973, 1974). W e will draw continually upon these contributions in subsequent chapters of the book. T h e heuristics to be explored are relatively prim itive and sim ple ju d g m en tal strategies. T h ey are not irratio n al or even n o n ratio n al. T h ey probably produce vastly m ore correct o r partially correct inferences than erroneous ones, and they do so with great speed and little effort. Indeed, we suspect that the use of such sim ple tools m ay be an inevitable feature o f the cognitive apparatu s of any organism that m ust m ake as m any ju d g m e n ts, inferences, and decisions as h um ans have to do. Each heuristic or, m ore properly, the m isapplication o f each heuristic, does lead people astray in som e im p o rtan t inferential tasks. Since this book is particularly concerned with inferential failings, it is the m isuse o f the heuristics— th eir application in preference to m ore norm atively ap p ro p riate strategies— that we will em phasize. A lthough we characterize the heuristics as “ju d g m en tal strategies, ” the term is m isleading in that it im plies a conscious and deliberate application o f well-defined decision rules. T h e heuristics to be explored should be distinguished from straightforw ard co m p u tatio n al or ju d g m e n ta l “ algorithm s” (such as the m ethod for finding square roots or deciding w hether o n e ’s bridge h an d m erits an opening bid), which generally are explicit and inv arian t both in the criteria for th eir use and the m a n n er of th eir application. T h e intuitive psychologist probably w ould not assent to, m uch less spontaneously express, any general form ulation of either heuristic. Instead, the utilization o f the heuristics is generally autom atic and nonreflective and notably free of any conscious consideration of ap propriateness. As we shall see, the heuristics are not applied in a totally indiscrim inate fashion. In m any contexts in w hich a given heuristic w ould prom ote erro r, people refrain from using it and probably could articulate why its use w ould be foolish. O n other logically equivalent and equally un p ro p itio u s occasions, people readily apply the sam e heuristic and m ay even attem p t to justify its use.

T H E AVAILABILITY H EU R ISTIC

W hen people are required to ju d g e the relative frequency o f p articu la r objects o r the likelihood o f p articu lar events, they often m ay be influenced by the relative availability of the objects or events, th at is, th e ir accessibility in the processes of perception, m em ory, or construction from im ag in atio n (cf. T v er-

Judgmental Heuristics and Knowledge Structures

19

sky & K ah n em an 1973). Such availability criteria often will prove accurate and useful. T o the extent that availability is actually associated with objective frequency, the availability heuristic can be a useful tool of ju d g m en t. T h ere are m any factors u n correlated w ith frequency, how ever, which can influence an e v e n t’s im m ediate perceptual salience, the vividness or com pleteness with w hich it is recalled, or the ease w ith which it is im agined. As a result, the availability heuristic can be m isleading.

Availability Biases in Frequency Estimation Let us proceed First by in tro d u cin g and then exploring in some detail three ju d g m en tal tasks for which application of the availability heuristic m ight lead one to biased estim ates o f the relative frequency of various objects or events. T h e First two exam ples are hypothetical (although we shall docum ent closely related experim ental results in later chapters). (1) A pollster who asks a sample of American adults to estimate the “ percentage of the work force who are currently unemployed” finds an “ egocentric bias.” That is, currently unemployed workers tend to overestimate the rate of unemployment, but currently employed workers tend to underestimate it. (2) An Indiana businessman confides to a friend, “ Did you ever notice how many Noosiers become famous or important? Look anywhere— politics, sports, Hollywood, big business, even notorious bank robbers— I couldn’t guess the exact figures, but I bet we Hoosiers have far more than our fair share on just about any list in Who's Who . ” (3) A group of subjects consistently errs in judging the relative frequency of two kinds of English words. Specifically, they estimate the number of words beginning with particular letters (for example, R or K ) to be greater than the number of words with those letters appearing third, although words of the latter type actually are far more numerous. Exam ples 1 an d 2 seem to present com m on and fam iliar errors, although one m ight not im m ediately recognize the role of availability factors in producing them . In fact, some readers m ight hasten to cite m otivational or even “ psychodynam ic” factors that could induce unem ployed w orkers to overestim ate the com m onness of th eir plight or th a t could pro m p t p roud In d ia n a residents to exaggerate th eir share of the lim elight. Exam ple 3 seems less intuitively obvious and at first seems quite unconnected to the o ther two exam ples. N evertheless, the chief source of erro r in all three cases seems to us to be the availability heuristic. C o n sid er E xam ple 1, about estim ates of u n em ploym ent. H ere the bias in subjective availability can be traced to a bias in initial sam pling. U nem ployed people are m ore likely to know an d m eet o th er unem ployed people than are

20

H um an Inference

job-holders, and vice versa. T h e reasons for such a sam pling bias are hardly m ysterious: T he unem ployed individual is likely to share the neighborhood, socioeconom ic b ackground, and occupation of other jobless individuals. H e also is likely to en co u n ter o ther unem ployed people in such everyday endeavors as jo b -h u n tin g , visiting em ploym ent agencies, collecting unem ploym ent benefits, and shopping at stores offering cu t-rate prices or easy credit. Indeed, he even m ay seek out such individuals for social com parison, inform ation exchange, or general com m iseration. T h u s, to the extent that the unem ployed person relies upon the sam ple g enerated by his personal experience, he will be m isled about the com m onness of unem ploym ent. In the same m an n er, em ployed people, who are apt to live, w ork, an d shop n ear one another, are apt to err in the opposite direction. It is im portan t to em phasize that the people in this hypothetical exam ple would not be com pelled to rely u p o n biased availability criteria in estim ating the frequency of unem ploym ent. T h ey could try to recall m edia presentations of data, could apply some p opular rule of th u m b ( “ W hen th e re ’s an energy shortage, jobs d isap p ea r” ), or could em ploy some m ore ap p ro p riate “ sam pling p ro ced u re” ( “ H ow m any people have I seen lining up outside m y neighborhood unem ploym ent office on the first of the m onth this year as compared with last y ear?” ). T h ey even could attem pt to com pensate for the biases distorting th eir sam ples of available d ata ( “ H ard ly anyone I know is jobless, but of course, I d o n ’t get to m eet m any unem ployed people, do I? I guess I ’d better adjust my estim ate u p w ard !” ). In d eed , it is quite likely th at some people would avoid availability criteria or at least w ould attem p t the necessary adjustm ents. T h ro u g h o u t this book, how ever, we present experim ental evidence show ing that sim ple, tem p tin g , availability criteria are used in contexts in which availability and frequency are poorly correlated and are used w ithout ap p ro p riate adjustm ents for the factors th at bias subjective experience. N ow let us consider Exam ple 2, about the relative p ro m in en ce of In d ian a natives. T h e H o o sier’s egocentric estim ate clearly contains some of the same features as in o u r initial exam ple. T h a t is, people from In d ian a are disproportionately likely to know or h ear ab o u t fam ous fellow H oosiers. Beyond such biases in initial exposure, how ever, this exam ple introduces the potential influence of additional biases in storage. W hen a n ational sportscaster says “ M y ra Swift of G randville, In d ian a and M ary Speed o f Bigtow n, Florida won gold m edals in the O lym pics y esterd a y ,” it is the accom plishm ent o f his fellow H oosier that the In d ian a businessm an is m ore likely to notice and to rem em ber. A ccordingly, the sam ple of fam ous people he subsequently can recall from m em ory will reflect biases at the “ sto rag e” stage as well as at the sam pling stage. Biases in exposure, atten tio n , and storage can arise, of course, from

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21

m any factors besides the kinship betw een the perceiver and the object. As we shall see in later chapters, for instance, oddity o r new sw orthiness could accom plish the same end. T h u s, people from all states m ight overestim ate the n u m b er of very big, very small, very young, very pretty, or very hirsute O lym pic gold m edalists because such factors would bias the ra te r’s likelihood of sam pling, storing, and recalling the pertin en t instances. E xam ple 3, ab o u t estim ates of the frequency of the letter R in the first versus the third position, is subtler. In fact, readers who try the experim ent them selves m ay find th at they m ake the sam e incorrect assessm ents of relative frequency as did the original subjects. O nce again, an in ap p ro p riate applica‫־‬ tion of the availability criterion is the source of the difficulty. Like the subjects in T v ersk y ’s and K a h n e m a n ’s (1973) dem o n stratio n , the reader probably finds that instances of w ords b eginning w ith R are easier to generate spontaneously (at least in a casual first attem pt) than are instances of w ords that have R as their third letter. But the differences in ease of generation do not reflect corresponding differences in word frequency. Any truly random sam ple of English w ords would reveal w ords b eginning with R to be m uch less com m on than w ords with R as their th ird letter. T h e relative difficulty of gen eratin g w ords like “ c a re ,” “ s tre e t,” and “ d e ra il,” m ay give interesting hints of the storage and retrieval of o n e ’s vocabulary, but it says virtually nothing about objective w ord frequencies. A n analogy m ay be instructive here: In a quick search of the library, one w ould find it easier to find books by authors nam ed W oolf than by authors nam ed V irg in ia, or to find books about A ustralia th an books by auth o rs born in A ustralia. Such differences obviously w ould indicate little about the relative frequencies of such books in the lib rary ’s collection. Instead, they would reflect the lib rary ’s system for referencing books and g ran tin g access to them . By the sam e token, first letters ap p aren tly are m ore useful cues than third letters are for referencing and p erm ittin g access to the items in o n e ’s personal w ord collection. O nce again, the use of criteria other th an the subjective ease of generation (or, alternatively, recognition of relevant biases and adequate com pensation) could lead people to a m ore accurate estim ate.

A v a ila b ility o f E vent R elationships and o f Causal E xplanations

K a h n e m a n ’s an d T v ersk y ’s work has been largely on the use of the availability heuristic in ju d g m en ts involving the frequency or probability of individual events. O th e r research indicates that subjective availability m ay influence ju d g m en ts of relationships betw een events, particularly causal relationships.

22

H um an Inference

J o n e s ’s and N isb ett’s (1972) account of the divergent causal in terp retations of actors and observers— from which observers cite “ d ispositional” factors (traits, abilities, attitudes, etc.) to explain behaviors and outcom es that the actors themselves attrib u te to “ situ atio n al” factors— is one case in point. For exam ple, the actor who gives a dollar to a beggar is apt to attrib u te his behavior to the sad plight of the beggar, but the observer of the behavior is apt to attribute it to the acto r’s generosity. From the acto r’s perspective, it is the constantly changing features of the en v iro n m en t that are particularly salient or “ available” as potential causes to which his behavior can be attributed. From the o b serv er’s perspective, the actor is the perceptual “ Figure” and the situation m erely “ g ro u n d ,” so that the actor him self provides the most available causal candidate. Indeed, by altering acto rs’ and observers’ perspectives th rough videotape replays, m irrors, or other m ethods, one can correspondingly alter the acto rs’ and o b serv ers’ causal assessm ents (cf. A rkin & D uval 1975; D uval & W icklund 1972; R egan & T o tten 1975; Storm s 1973). Subsequent research by a n u m b er of investigators, most notably T ay lo r and her associates (for exam ple, T ay lo r & Fiske 1975, 1978), has dem onstrated a m ore general point regarding availability an d causal assessm ent. It appears that almost any m an ip u latio n that focuses the p erceiv er’s attention on a potential cause, for exam ple, on a particu lar p articip an t in a social interaction, affects causal assessm ent. W hether the atten tio n al m anipulation is achieved by a blunt instruction about which p articip an t to w atch, subtle variations in seating arran g em en t, or by “ solo” versus “ nonsolo” status of, for exam ple, female or black p articipants, the person m ade disproportionately “ available” to onlookers is seen to be a disproportionately potent causal agent. (See also M cA rth u r & Post 1977; M cA rth u r & Solom on 1978.) A vailability effects also m ay account for other biases involving perceived causality. C onsider F ischhoff s (1975; Fischhoff & Beyth 1975) reports on the subjective certainty of hindsight know ledge. These reports show that outcomes often seem in retrospect to have been inevitable. T his m ay be because the antecedents and causal scenarios that “ p red icted ” such outcom es have far greater “ after-the-fact” availability than do antecedents or scenarios that predicted alternative outcom es that did not in fact occur. In a sim ilar vein, Ross, Lepper, Strack, and Steinm etz (1977) dem o n strated that explaining why some event is consistent with know n preceding events (for exam ple, explaining the suicide of a clinical patient whose case history one has exam ined) tends to increase the subjective likelihood that the event actually did occur. A gain, the relevant m echanism appears to be the availability heuristic. T h e explanation creates a p articu lar causal scenario, an d its causal factors are disproportionately available to the perceiver w hen predictions are m ade later.

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23

In both hindsight and explanation, the subjective ease of generation appears to be im p o rtan t. T h e subjects seem to respond not only to the m ere presence o f potential causal scenarios b ut also to the relative ease w ith which they were detected or invented. People probably im plicitly assum e this subjective ease of g eneration to be som ehow sym ptom atic of the scenario’s likelihood or of the ex p lan atio n ’s aptness.

A ppropriate and Inappropriate A pplications o f th e A v a ila b ility H euristic

An indiscrim inate use of the availability heuristic clearly can lead people into serious ju d g m en tal errors. It is im p o rtan t to reem phasize th at in m any contexts perceptual salience, m em orability, and im aginability m ay be relatively unbiased and therefore well correlated w ith tru e frequency, probability, or even causal significance. In such cases, of course, the availability heuristic often can be a helpful an d efficient tool of inference. T h e sam e jobless individuals whose estim ates of unem ploym ent rates were distorted by the availability heuristic could m ake a reasonably accurate estim ate of the p rep o n d eran ce of oak trees to m aple trees in their neighborhood by using the sam e strategy. In estim ating the frequencies of various types of trees, the in d iv id u al’s personal experiences and subsequent recollections w ould constitute generally unbiased sam ples. Sim ilarly, the In d ian a resident who was m isled by the d isp roportionate availability o f instances of fam ous fellow H oosiers m ight have fared quite well if the sam e heuristic had been applied in estim ating the success of G erm an O lym pians relative to Italian O lym pians. F u rth erm o re, the “ ease of g en era tio n ” criterion w ould have helped rath er than hin d ered T v ersk y ’s and K a h n e m a n ’s subjects if the experim ental task had been to estim ate the relative frequencies either o f a) w ords b eginning w ith R versus words b eginning with L, or b) w ords w ith R versus L in the th ird position. In either of these cases, d i f ferences in the relative ease of generation w ould have reflected differences in frequency quite accurately. T h e norm ative status of using the availability heuristic, and the p rag m atic utility of using it, thus depend on the ju d g m en tal dom ain and con* text. People are not, of course, totally unaw are that sim ple availability criteria m ust som etim es be discounted. F or exam ple, few people who were asked to estim ate the relative n u m b er of moles versus cats in th eir neighborhood w ould conclude “ there m ust be m ore cats because I ’ve seen several of them b u t I ’ve never seen a m o le .” N evertheless, as this book docum ents, people often fail to distinguish betw een legitim ate and superficially sim ilar, but illegitim ate, uses of the availability heuristic.

THE REPRESENTATIVENESS H EU R ISTIC

T h e second ju d g m en tal heuristic to be introduced is one which K ahnem an and T versky (1972, 1973; T versky & K ah n em an 1974) term ed the representativeness heuristic. T his heuristic involves the application of relatively simple resem blance or 4‘goodness of fit” criteria to problem s of categorization. In m aking a ju d g m en t, people assess the degree to which the salient features of the object are representative of, or sim ilar to, the features presum ed to be characteristic of the category. In the following sections we try to provide a coherent g ro u p in g of exam ples. It should be em phasized, how ever, th at our classification system is neither exhaustive n o r theoretically derived. W e also should note th at we m ake no attem p t to specify the precise criteria by which individuals calculate the representativeness of one object or event to an o th er. (For the interested reader, a recent b ut already classic pap er by T versky, 1977, takes a first step in this direction by intro d u cin g a form al theory of sim ilarity ju d g m e n ts.)

Judgm ents of the Degree to W hich O utcom es Are R epresentative of T heir O rigins

People often are req u ired to predict some outcom e or ju d g e the likelihood of some event on the basis of inform ation about the “ g en eratin g process” that produced it. O n such occasions, the ju d g m e n t is likely to reflect the degree to which the specified outcom e represents its origin. Let us consider an exam ple adapted from one used by K ah n em an and T versky (1972): Subjects are asked to assess the relative likelihood of three p articu la r sequences of births of boys (B) and girls (G ) for the next six babies b o rn in the U nited States. T hese sequences are i) BBBBBB, ii) G G G B B B , iii) G BBG G B . A ccording to the conventional probability calculation, the likelihood of each of these sequences is alm ost identical. (A ctually, the first sequence is slightly m ore likely than either the second or th ird sequence, since m ale b irth s are slightly m ore com m on than female births. T h e latter two sequences are simply different orderings of identical, in d ep en d en t events.) Subjects who rely upon their intuitions and upon the representativeness criteria which guide such intuitions, are apt to regard the G B B G G B sequence as far m ore likely than either of the other two. In doing so, they are responding to w hat they know about the population of babies and about the processes of “ g e n e ra tio n ,” that is, that each b irth is a “ ra n d o m ” event in w hich the probability of “ bo y ” and “ g irl” are nearly equal. O nly the G B B G G B sequence is “ rep resen tativ e” of the g en eratin g process. T h e G G G B B B sequence seem s 24

Judgmental Heuristics and Knowledge Structures

25

too ‘ ‘o rd e rly ” to represent a random process. T h e BBBBBB sequence satisfies the criteria even less: It captures n eith er the random ness of the b irth process nor the equal sex distrib u tio n of the p opulation from which the six births w ere “ sam pled. ” T h e representativeness heuristic also accounts for the fam iliar “ g am b lers’ fallacy.” A fter observing a long ru n of “ re d ” on a roulette wheel, people believe that “ b lack ” is now due, because the occurrence of black w ould m ake the overall sequence of events m ore representative of the g en eratin g process th an w ould the occurrence o f another red. In a sim ilar vein, any researcher who has ever consulted a random n u m b e r table for an un b iased o rd erin g of events has probably felt that the result was somehow insufficiently “ rep resen tativ e” of a chance process, that it contained suspiciously orderly sequences, suspiciously long runs, suspicious overrepresentations o r u n d errep resen tatio n s of p articu lar n u m b ers early or late in the sequence, an d so forth (cf. T versky & K ah n em a n 1971).

Ju dgm en ts o f the Degree to W hich Instances Are R epresentative of Categories

M an y everyday ju d g m en ts req u ire people to estim ate the likelihood that some object o r event w ith a given set of characteristics is an instance of some designated category o r class. Typically, the ju d g m en ts are m ade in relative term s, that is, is Event X m ore likely to be an instance of Class A o r of Class B? C o n sid er the following problem , which is sim ilar in form to those in the em pirical w ork by K ah n em a n and T versky described in detail in a later chapter. T h e present authors have a friend who is a professor. H e likes to w rite poetry, is rath e r shy, and is small in stature. W hich of the following is his field: (a) C hinese studies or (b) psychology? T hose readers who quickly and confidently predicted “ psychology” p robably applied som e version, w hether sophisticated o r crude, of conventional statistical canons. W e co n gratulate these readers. W e suspect, how ever, that m any readers guessed “ C hinese stu d ie s,” o r at least seriously considered that such a guess m ight be reasonable. If so, they probably were seduced by the representativeness heuristic. Specifically, they assessed the relative “ goodness of fit” betw een the professor’s personality profile and the p red o m in an t features of th eir stereotypes o f Sinologists and psychologists. F inding the fit b etter for the form er than for the latter, they guessed the professor’s field to be C hinese studies. In succum bing to the lure of the representativeness heuristic, what the read e r likely has overlooked or not appreciated is some relevant category base‫־‬ rate inform ation . Let the read er who guessed “ C hinese stu d ies” now reconsider that guess in light of the relative nu m b ers of psychologists and

26

H um an Inference

Sinologists in the population. T h e n consider the m ore restricted p o p ulation of people likely to be friends of the authors, who them selves are psychologists. Surely no re a d e r’s im plicit personality theory o f the strength of association betw een academ ic discipline an d the professor’s various characteristics, that is, poetry-w riting, shyness, an d slightness o f stature, w arran ts o v errid in g such base-rate considerations. E rrors in problem s of the Sinologist/psychologist variety m ay reflect that the ju d g e has been led to answ er the w rong question or, m ore specifically, to p o nder the w rong conditional probability. T h e ju d g e seems to be resp o n d in g to the question “ H ow likely is it th a t a psychologist (versus a Sinologist) w ould resem ble the personal profile p ro v id ed ?” w hen the actual question posed is “ H ow likely is som eone resem bling the personality profile to be a psychologist (versus a Sinologist)?” T h e representativeness heuristic leads people to give a sim ilar answ er to the two questions, since it entails consideration only o f the resem blance of the two occupational stereotypes to the given personality description. T h e erro r is the failure to consider the relevant base rates or m arginal probabilities, a consideration which is irrelevant to the first question but critical to the second. A lthough a m uch h igher p ro p o rtio n of Sinologists than of psychologists m ay fit the profile, there w ould still be a m uch greater absolute n u m b er of psychologists th an of Sinologists who fit it, because of the vastly g reater n u m b er of psychologists th an of Sinologists in the population. W e discuss these issues at m uch greater length in subsequent chapters, especially in chap ter 7 in which we discuss the effect of representativeness on a wide variety of prediction problem s.

Judgm ents o f the Degree to W hich A ntecedents Are R epresentative o f C onsequences

E arlier we contended th at the availability of causal candidates, or of causal scenarios linking outcom es to potential an tecedents, influences assessm ents of causality. W e contend th at representativeness criteria also m ay be im p o rtan t to such inferences. T h a t is, a person who is req u ired to account for som e observed action or outcom e m ay search the list o f available antecedents for those that seem to be the m ost representative “ cau ses” of the know n “ conseq u en ces.” Sim ple resem blance criteria ap p ear to influence causal assessm ent ju s t as they influence ju d g m en ts o f the representativeness of outcom es to origins or instances to classes. As we see in ch ap ter 6, som etim es the resem blance criterion is used in a crude an d unsophisticated w ay, as it is in p rim itive medical beliefs attrib u tin g a p articu lar illness to an en v iro n m en tal ag en t w ith features resem bling the illness. Som etim es its influence is less p aten t, as in the

Judgmental Heuristics and Knowledge Structures

27

preference for m otivational causes in explaining events with strong m otivational or affective consequences or the preference for com plicated, m ultifaceted causes for com plicated, m ultifaceted outcom es. G enerally, the use of the representativeness heuristic in causal assessm ent is m ore th an a sim ple com parison of the features of effects with those of th e ir potential causes. N orm ally, people also use theories or general knowledge of the p articu lar antecedents likely to cause or explain given outcom es and of the specific outcom es likely to follow given antecedents. A p erso n 's belief th at the cause o f E g y p t’s diplom atic initiative tow ard Israel was an heroic vision of E g y p t’s leader rath e r than econom ic exigency does not reflect m erely a crude assessm ent of the sim ilarity betw een historic gestures and heroic visions. Instead, such assessm ents reflect ju d g m en ts of the sim ilarity of known effects and potential causes to tacit o r explicit m odels of cause‫־‬an d ‫־‬effect relations in in tern atio n al conduct. A pplication of the representativeness heuristic to the assessm ent of causality thus ranges from the crude and questionable requirem en t th at potential causes resem ble effects, to norm atively p ro p er strategies based on a com parison of the sim ilarity of observed effects and potential causes to generalized cause-and-effect models in the given dom ain.

A ppropriate and Inappropriate A pplications o f the R epresentativeness H euristic

Even m ore th an the availability heuristic, the representativeness heuristic is a legitim ate, indeed absolutely essential, cognitive tool. C ountless inferential tasks, especially those req u irin g induction o r generalization, depend on deciding w hat class o r category of event one is observing; such ju d g m e n ts inevitably hinge upon assessm ents o f resem blance o r representativeness (cf. T versky 1977). Even in o u r exam ples, the use of the representativeness heuristic produced errors only because it was overapplied o r m isapplied while norm atively im p o rtan t criteria were overlooked. L et us briefly reconsider each of those exam ples. In the case of the representativeness o f the outcom e to the origin, the problem is clearly one of overapplication. T h e insight that the features of the sam ple ought to resem ble those o f the population or the gen eratin g process is generally valid. It leads people to recognize th at an all-m ale or an all-white ju ry is m ore likely to reflect a biased selection procedure th an will a ju ry w ith a m ore p ro p o rtio n ate rep resen tatio n of the overall population. It also leads people to cry foul w hen a politician ’s cronies seem to enjoy a d isproportionate share of good luck in th eir transactions w ith local or state agencies. U nfortunately, w hen peo p le’s u n d erstan d in g of the gen eratin g process and its im plications is deficient— as w hen there are m isconceptions about ra n d o m n e ss— the representativeness heuristic will m islead.

28

H um an Inference

In the second exam ple, the Sinologist/psychologist problem , people are foiled m ainly because im p o rtan t inform ation is neglected, th a t is, the relevant base rates are ignored. In m any circum stances, of course, such inform ation is absent, and the representativeness heuristic has no serious co ntender. In other circum stances, base-rate inform ation m ay have little practical significance. Som etim es the featu re-m atch in g process results in a category determ ination with a probability n ear 1.0, an d when features are as pow erfully diagnostic as that, there is little practical need to consider base rates. F or exam ple, in the Sinologist/psychologist problem , if the profile were extended to include the inform ation th at the person speaks C hinese, know s no statistics, and has never heard o f B. F. Skinner, the relevance of base-rate frequencies w ould dw indle to triviality. T h ere are also occasions when representativeness criteria can be used directly w ithout violating no rm ativ e stan d ard s because the base rates or m arginal probabilities are approxim ately equal. If the Sinologist/psychologist problem were altered to a decision betw een a sociologist and an historian, the representativeness heuristic w ould serve the ju d g e quite well, providing that the relevant occupational stereotypes had at least some validity.

KNOW LEDGE STRUCTURES: TH EO R IES AND SCHEM AS

W e have discussed some of the ju d g m en tal strategies that people use in a variety of social inference tasks. O ften , how ever, peo p le’s u n d erstan d in g of the rapid flow of co n tinuing social events m ay d epend less on such ju d g m e n ta l procedures than on a rich store of general know ledge of objects, people, events, and their characteristic relationships. Som e of this know ledge m ay be represented as beliefs or theories, that is, reasonably explicit “ p ro p o sitio n s’ ‫י‬ about the characteristics of objects or object classes. (For exam ple: Jo e is kind to small anim als. R o tarian s are public spirited. A dult neuroses have th eir “ o rig in ” in childhood trau m a. D ecision m akers prefer m inim ax strategies.) P eople’s generic knowledge also seems to be o rganized by a variety of less “ p ro p o sitio n al,” m ore schematic, cognitive stru ctu res (for exam ple, the know ledge underlying o n e ’s aw areness of w hat h appens in a re sta u ra n t, o n e ’s u n d erstan d in g of the G ood S am aritan p arable, o r o n e ’s conception o f w hat an introvert is like). T o describe such know ledge stru ctu res, psychologists refer to a grow ing list of term s, including “ fram es” (M insky 1975), “ scrip ts” (A belson 1976; Schank & Abelson 1977), “ nuclear scenes” (T o m k in s 1979), and “ p rototypes” (C an to r & M ischel 1977, in press), in addition to the earlier and m ore general term “ schem as” (B artlett 1932; Piaget 1936; also R u m e lh art 1976). In the following discussion we largely forsake any attem p t at classifying

Judgmental Heuristics and Knowledge Structures

29

or defining the possible stru ctu res. (See Schank & Abelson 1977, Abelson 1978, and T aylo r & C ro ck er 1980.) W e do, how ever, observe the distinction betw een beliefs or theories that can be sum m arized in one or m ore simple propositions, and o th er m ore schem atic structures. Both types of knowledge structures are im p o rtan t because they provide an interpretative fram ew ork for the lay scientist— one that resolves am biguity and supplem ents the inform ation “ given ” w ith m uch “ assu m ed ” inform ation.

T heories and T heir Im pact

In the following chapters we em phasize repeatedly the extent to which the intuitive scientist’s d ata are assim ilated to preexisting im pressions, beliefs, an d theories. C h ap ter 4 describes how theory-based preconceptions guide the initial process o f d ata coding. C h ap ters 5, 6, and 7 exam ine respectively, the effect of such preconceptions on biasing estim ates of covariation, assessm ents of causality, and predictions of one variable from knowledge of another. C h a p te r 8 deals w ith the processes by which theories survive, and occasionally yield to, various evidential or logical challenges. C h ap ter 9 discusses the part played by im plicit theories in the lay scientist’s u n d erstan d in g of his own behavior and m ental processes. O u r final two chapters expand upon the potential cost and benefits that accrue to the theory user. In this chapter, we restrict ourselves to em phasizing the role of lay psychological theory first in the application o f the representativeness heuristic and then in a variety of attrib u tio n al ju d g m en ts. T h e types of theories to be considered vary from the relatively narro w generalizations that people m ake about p articu lar individuals or groups, to the broadest conceptions of h u m an n atu re and the d eterm in a n ts of h u m a n behavior.

T heory-b ased Judgm en ts o f R epresentativeness

As we noted earlier, assessm ents of representativeness often depend less on sim ple sim ilarity criteria th an on m ore sophisticated “ th eories” of the types of attrib u tes and events that occur together, or that cause each other. F or exam ple, scandal in a p arliam en tary governm ent is a “ rep resen tativ e” cause of an im p en d in g election. W hen a scandal occurs we expect an election an d w hen an election is called we are apt to cite any previous scandal as a contrib u tin g cause. T h e reason for such ju d g m en ts clearly is not in the relative sim ilarity o f the o u tstan d in g features of political scandals and p arliam en tary elections. R ath er, the ju d g m e n t reflects o n e ’s adherence to a pair of “ th eo retical” propositions, first, th at scandals w eaken governm ents and second, that w eakened governm ents in p arliam en tary dem ocracies often m ust go

30

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to the electorate for a vote of confidence. Som etim es, as we shall see, the preconceptions governing causal inferences and likelihood assessm ents m ay best be regarded not as a set of propositions b u t as a schem a or ‘‘scrip t’ ’ (cf. A belson 1976) in which a succession of ‘‘scenes’’ are linked in a single coherent stru ctu re— for exam ple, accusations, denials, fresh accusations, lim ited acknow ledgm ents of b ad ju d g m e n t an d m endacity, resignations, an d a final em otional appeal by the political leader for su p p o rt at the polls. People rely upon an enorm ous n u m b e r of such theories, which are derived from personal experience and from the accum ulated wisdom o f o n e ’s culture, to decide on the representativeness of causes an d effects, outcom es and outcom e-generating processes, and objects an d classes. T h e costs an d benefits of relying upon such specific prio r theories, rath e r th an collecting an d analyzing fu rth er data, for instance, d epend both on the accuracy of the theories and on the feasibility of em ploying other, m ore em pirical p rocedures.

Global T heories and Situational Versus D isp osition al A ttribution

P erhaps the m ost significant an d far-reaching of the intuitive scien tist’s theories are those addressing the general causes of h u m a n behavior. T h ese theories determ ine the m ean in g we extract from social in teraction, an d , in large m easure, they determ in e the way we behave in response to the actions of o u r fellows. For exam ple, the lay scientist, like the professional psychologist, believes that rew ards for p articu lar behaviors increase the su b seq u en t likelihood of such behaviors and th at pun ish m en t decreases th eir likelihood. T h e lay scientist, like the professional, believes th at peo p le’s b eh av io r is guided by plans and goals an d believes that people seek to m axim ize pleasure and m inim ize pain. Such tacit, “ global” theories, as well as m any m ore specific theories, including theories about specific individuals or classes of individuals, govern o u r u n d erstan d in g of b eh av io r— o u r causal ex planations of past behavior and o u r predictions of future behavior. T h ere has been surprisingly little research on those beliefs and theories shared by the mass of people in o u r culture. H eid er (1958) was perh ap s the first to em phasize th eir im portance, an d A belson (1968) was the first (an d very nearly the only) investigator to attem p t to study them em pirically. W h at little research has been done on people’s theories has focused on in dividual differences in the beliefs an d theories. C hristie an d G eis (1970), for exam ple, identified a set of cynical views about h u m an n a tu re th at characterizes the highly “ M achiav ellian ” individual an d explains his success in m an ip u latin g his m ore tru stin g peers. Even m ore relevant to p resent concerns, R o tte r and others (R o tter 1966; Collins 1974; C ran d all, K atkovsky, & C ran d all 1965;

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L efcourt 1972) investigated general inclinations tow ard internal versus external explanations (that is, personal effort and ability versus the vicissitudes of chance) in accounting for personal an d social outcom es. M ore recently, Seligm an (1975), discussed the part that p eo p le’s theories of the controllability of outcom es and of the causes of success and failure m ay have in the clinical syndrom e of depression. T h e m ost general and encom passing lay theory of h u m an b ehavior— so broadly applied that it m ight m ore aptly be term ed a “ m etath eo ry ” — is the assum ption that behavior is caused p rim arily by the en d u rin g and consistent dispositions of the actor, as opposed to the p articu lar characteristics of the situation to which the actor responds. T h ro u g h o u t this book we refer to what Ross (1977a, 1978; Ross & A nderson 1980) called the “ fundam ental attrib u tio n e rro r” — the tendency to attrib u te behavior exclusively to the ac to r’s dispositions and to ignore pow erful situational d eterm in an ts of the behavior. In ch ap ter 6, we argue that such errors are determ in ed partially by perceptual factors. Such erro rs probably are also p ro m p ted partially by dom ain-specific theories, for exam ple: “ Successful people are am bitious and m o tiv ated ” ; “ People who h u rt o th e rs’ feelings are rude and not well ‘brought u p .’ ” But in large m easure the erro r, we suspect, lies in a very broad proposition about h u m a n conduct, to w it, that people behave as they do because of a general disposition to behave in the way that they do. It is difficult to prove th at people adhere to an y th in g like an overarching “ general th e o ry ” of the relative im pact of dispositional versus situational factors. T h ere is reason to suspect, nevertheless, that a rath er general, “ dispositionalist th e o ry ” is shared by alm ost everyone socialized in o u r culture. C ertain ly , it is a part of the w orld view of the so-called P rotestant ethic that o n e ’s virtues and successes ultim ately reflect o n e ’s w orthiness and, conversely, that o n e ’s vices and failings reflect o n e ’s unw orthiness. A ccording to this view, good or bad luck, accidents of b irth , an d situational adversities m ay forestall m atters b ut o n e ’s fate will eventually m irro r o n e ’s character, and o n e ’s personal traits an d abilities will ultim ately prevail over circum stances. T his m essage is as present in H en ry F ielding’s novels as it is in H o ratio A lg er’s sentim ental doggerel. It is the set of beliefs which M ax W eb er (1904) long ago identified as a precondition for the rise of capitalism , and it is consistent w ith the m any philosophical positions that have assigned central roles to the concepts of personal responsibility and free will. T h e “ dispositionalist th e o ry ,” in short, is thoroughly woven into the fabric of o u r cu ltu re. N ot surprisingly, therefore, children grow ing up in o u r culture come to hold an increasingly dispositional view of the causes o f behavior (R oss, T u rie l, Jo sep h so n , & L ep p er 1978). T h e opposite view, the “ situ atio n alist” position, does not lack advocates. It is espoused by m ost con tem p o rary experim ental social psychologists, behaviorists, and role-theory sociologists. (In a sense, the view

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is also part of the econom ic determ inism of classical M arx ism .) I h i s alter‫־‬ native view, which was perhaps first explicitly articulated by Lew in (1935), m aintains that behavior is understood best in term s of states and intentions that are them selves the product of those situational stim uli p ertin en t to the individual at the m om ent of action. Such a view garners support, to which we will refer in later chapters, from two sources: O n e is the failure o f researchers to dem onstrate an y th in g like the cross-situational consistency in behavior dem anded by the dispositionalist view (cf. H artsh o rn e & M ay 1928; N ew com b 1929; and m ore generally M ischel 1968). T h e second source of support for the situationalist position is in the m any studies that d em o n strate that seem ingly insubstantial m anipulations of situational factors can control behavior dram atically and can greatly restrict individual differences. T h e mass of people m ay be seen to act in ways that seem either cow ardly or b rave, honest or dishonest, prejudiced or u n p rejudiced, or apathetic or concerned, depending on the situational constraints and op p o rtu n ities present at the tim e of action. W e do not wish to im ply that the evidence massively or u n am biguously supports a situationalist view. T h e recent 4‘m etatheory sh ift” in the social sciences, like all such m atatheory shifts or new £4p arad ig m s’‫( י‬K u h n 1962), is currently quite u n d erd eterm in ed by the available d ata. P erhaps the chief evidence supporting the situationalist view is the co n tin u in g ability of social scientists, even those who subscribe to the situationalist view, to be surprised by evidence both of the lack of individual consistency in dispositional tendencies and of the pow er o f m anifestly 44w eak” situational factors to control behavior. W hether it is the layperson’s m etatheory or the social scientist’s th at is correct (cf. Bern & Allen 1974, Bern & F u n d er 1978), the m etatheory exerts a pronounced influence on people’s ju d g m en ts of the causes and m eanings of behavior. O ften, as we will dem onstrate, this m arked dispositional bias can be shown to be incorrect.

Schemas, Scripts, and Personae

To u n derstan d the social w orld, the layperson m akes heavy use o f a variety of knowledge structures norm ally not expressed in propositional term s and possibly not stored in a form even analogous to propositional statem ents. In describing these cognitive structures we shall use the generic designation 44schem a” and will com m ent in detail about only two types of schem as—event-schem as, or 44scrip ts,” and person-schem as, or 44p e rs o n a e .” T h e most basic type of schem a is probably that which underlies the use of com m on concepts or categories such as dog, tree, or chair, or concepts of far greater or lesser generality (animals, flora, and furniture, or Airedales, Ponderosa

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pines, and Chippendales). In recent years there has been an explosion of interest in and research on p eo p le’s use of categories, and we cannot digress to sum m arize this im p o rtan t and ev er-expanding literatu re. Let us note m erely that the ‘ ‘classic” view of a category, one that entails clearly specified boundaries and a set of defining characteristics necessary to and sufficient for category m em bership, has com e u n d er increasingly devastating attack (cf. W ittgenstein 1953; R osch 1978; T versky 1977). G radually it has been supplanted by a m ore lenient and catholic view — one th at allows am biguous boundaries, recognizes a variety of differing bases for assessing category m em bership, and perm its individual m em bers to differ in th eir prototypicality. W hat both the traditional and new er views have in com m on is the notion that the category and the concept u n d erly in g it form an im p o rtan t basis for inference. T h a t is, once the criteria for applying the concept have been m et, the concept user readily assigns a n u m b e r of additional characteristics to the entity. For exam pie, upon deciding on the basis of a p articu lar an im a l’s appearance that it is a 4‘d o g ,” one m akes the inferential leaps that it is trainable, capable of loyalty, able to b ark , and likely to chase cats but is unlikely to clim b trees, p u rr, or wash its coat. In principle one could speak of a dog “ sch em a ,” or even an A iredale schem a or an anim al schem a. In practice, how ever, the term “ schem a” has com e to be differentiated from the term “ co n ce p t.” Since its intro d u ctio n in the 1930s by B artlett (1932) and by Piaget (1936), the term “ schem a” has been used m ore and m ore to refer to those m ental structures having a dynamic or relational aspect. F or exam ple, Piaget refers to a “ th u m b -su ck in g ” schem a and a “ co n serv atio n ” schem a, both of which, despite the enorm ous difference in th eir level of abstractness, have dynam ic relationships am ong the sch em a’s com ponents. In the form er, the schem a is a kind of m ental sum m ary of the sensory, cognitive, an d m o to r experiences in a sequence of actions involving body parts. In the latter, the schem a represents experiential know ledge of the relationship betw een m ass and volum e (or n u m b er an d position) and the outcom es likely to result from various action sequences involving a fixed m ass of m aterial (or a fixed n u m b e r of objects). Kelley (1972b) in tro d u ced to the attrib u tio n literatu re the notion of a causal schem a. Kelley used the term to refer prim arily to a highly abstract, content-free notion of the form al relations am o n g causes and effects. H e proposed th at people possess in very abstract and general form the notions of sufficiency and necessity in causal relations. T h is distinction underlies a n u m b e r of specific causal schem as, such as the single necessary cause schem a (in w hich the existence of the effect carries w ith it the certainty th at a particular cause was present) and the m ultiple sufficient cause schem a (in which the existence of the effect im plies the possibility of each of several causes). T h ere also are m ore com plicated general schem as. For exam ple, people m ay have a “ d isco u n tin g ” schem a: G iven an effect capable of being produced by

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several causes and certain know ledge of the o peration of a p articu la r cause, people reduce th eir subjective probability th a t each ol the o th er sufficient causes were operative. People also m ay possess an inhibitory cause schem a: G iven knowledge of the existence of a factor o p eratin g to block the occurrence of the effect, people infer that one or m ore facilitative causes were unusually pow erful. T h o u g h we are not confident th at people actually possess such contentfree causal schem as, we will use the term occasionally, to refer p rim arily to causal-analytic strategies that people do not seem to u n d erstan d o r to use in situations in which they w ould be helpful.

Scripts

T h e lexicons of cognitive social psychology and artificial intelligence recently were enriched by the in troduction of the “ scrip t’’ concept (A belson 1976, 1978; Schank & Abelson 1977). A script is a type of schem a in which the related elem ents are social objects and events involving the individual as actor or observer. U nlike most schem as, scripts generally are event sequences extended over tim e, and the relationships have a distinctly causal flavor, th at is, early events in the sequence produce or at least ‘ ‘e n a b le '’ the occurrence of later events. A script can be com pared to a cartoon strip w ith two o r m ore captioned “ scenes,” each of which sum m arizes some basic actions th at can be executed in a range of possible m an n ers and contexts (for instance, the “ restau ran t scrip t” with its “ e n te rin g ,” “ o rd e rin g ,” “ e a tin g ,” and “ exitin g ” scenes). A lternatively, a script can be represented as a co m p u ter program w ith a set of tracks, variables, relationships, o perations, su b ro u tin es, loops, and the like, which are “ in sta n tia ted ” w ith p articu lar values for any p articu lar application of the script. T h u s, the re sta u ra n t script has a coffee shop track, a C hinese restau ra n t track, a cafeteria track, perh ap s even a M cD o n ald ’s track. T h e variable representing the decor m ay take on the value “ fancy” o r “ c ru m m y .” T h e w aiter values include “ p o lite ,” “ s u rly ,” and “ bad enough to pro m p t a c o m p la in t.” E xiting entails the operational options “ pay w aiter” o r “ pay c ash ie r,” and so forth. Scripts can vary in m any ways. T h ey can be highly abstract, culturally pervasive, and m ay owe th eir existence only slightly to direct personal experience (for exam ple, the script th at links “ te m p ta tio n ,” “ tra n sg re ssio n ,” and “ retrib u tio n ” ). O r they m ay be highly concrete, idiosyncratic, and directly tied to experience (for exam ple, the scripted episode in which D ad d y comes hom e from w ork, asks M om m y w h a t’s for d in n e r, she gets annoyed and sulks and, d ep en d in g on w hat his day has been like, he either apologizes o r gets angry too). T h e im portance of scripts to the intuitive scientist lies in the speed and ease with which they m ake events (or secondhand accounts of

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events) readily com prehensible and predictable. T h e ir potential cost, as always, is the possibility o f erroneous in terp retatio n s, inaccurate expectations, and inflexible m odes of response.

Personae

C en tral to any d ram atic script is the dramatis personae, or cast o f characters. Indeed, to specify the characters is often sufficient to convey m uch of the action of the script (for exam ple, “ the prostitute with the h eart of gold an d the scholarly b u t naive young m a n ” or “ the crusty b u t benign older physician and the hot-headed, idealistic young su rg eo n ” ). Social ju d g m en ts and expectations often are m ediated by a class of schem as w hich we shall term “ p e rso n a e ,” that is, cognitive structures rep resen tin g the personal characteristics an d typical behaviors of p articular “ stock c h a ra c te rs.” Som e personae are the u n iq u e products of o n e ’s own personal experience (good old A u n t M ary , C oach W hiplasch). O thers are shared w ithin the culture or subculture (the sexpot, the earth -m o th er, the girl-nextdoor, the redneck, the schlem iel, the rebel-w ithout-a-cause). M any of the shared personae are borrow ed from fiction (S h ak esp eare’s to rtu red H am let or television’s bigoted A rchie B unker) or even from the popularized professional ja rg o n of psychology and psychiatry (the a u th o ritarian , the “ T y p e A ” personality, the anal-com pulsive). O u r store of personae is au g m en ted fu rth er by m etaphors draw n from the anim al kingdom and from the m any occupational roles in o u r society. A nim al or occupational personae are apt to be very simple and “ concept-like,” p rim arily highlighting a lim ited set o f physical or behavioral characteristics. H ence, we readily u n d erstan d , an d are apt to be strongly influenced by, rem arks like, “ W h at do you see in that big ox,” or “ I w o u ld n ’t tru st that viper if I were y o u ,” or “ H e w ants you to be his H a ld e m a n ,” or “ S urgeon Blochit is a real b u tc h e r” (or, alternatively, “ B utcher Phelps is a real su rg eo n ” ). In each instance the persona constitutes a know ledge stru ctu re which, w hen evoked, influences social ju d g m en ts and behaviors. O nce the principal features o r behaviors o f a given individual suggest a p articu lar persona, su b seq u en t expectations o f and responses to th at individual are apt to be dictated in part by the characteristics of the persona. T h e concept of a persona is not essentially different from that of a stereotype. W e prefer the term persona, how ever, because it lacks the pejo rativ e im plications of the term “ stereo ty p e,” which has been used to describe culturally shared, indeed hackneyed, notions of particu lar groups of people. T h e persona is also sim ilar to the notion o f a “ p erso n -p ro to ty p e,” proposed an d investigated by C a n to r an d M ischel (1977, in press).

A va ila b ility , R epresentativeness, and the Arousal o f K now ledge Structures

T h e notion that the lay p erso n ’s experience, u n d erstan d in g , and inferences are stru ctu red by a great and varied store of schem as is intuitively satisfying. Indeed, it has becom e increasingly clear to theorists w orking in alm ost all areas of psychology that the schem a construct is a cornerstone of psychological theory (N eisser 1976). W orkers in social in teractio n (B erne 1964; G offm an 1959), personality and psychopathology (G . K elly 1955, 1958), visual perception (M insky 1975), and especially in language com prehension and artificial intelligence (Abelson 1978; Bobrow & C ollins 1976; Bower, Black & T u rn e r in press; R u m elh art, 1976; R u m e lh art & O rto n y 1976; Schank 1975) all have m ade essentially the sam e p o in t— that objects and events in the phenom enal world are alm ost never approached as if they were sui generis configurations b u t rath er are assim ilated into preexisting structures in the m ind o f the perceiver. U nfortunately, the increasing conviction th a t schem as exist and are im p o rtan t has not been accom panied by a co m m en su rate increase in o u r knowledge of them . T h ere still is little evidence th at m ight clarify their p roperties or define the type of work they perform . M ost critical of all, perh ap s, is o u r ignorance of the conditions of their instigation an d use. In 1961, D e Soto w rote of o u r ‘‘crippling ignorance o f the dynam ics o f schem a aro u sa l” (p. 22), and a decade later Kelley (1972b) was obliged to echo D e S o to ’s com plaint. R ecently, how ever, m atters have b egun to im prove. F o r instance, M arkus (1977) showed that the speed w ith which in fo rm atio n about the self is processed m ay be predicted by the presence or absence of schem atic selfconcepts or ‘'self-schem as.” Sim ilarly, C a n to r’s and M ischel’s work (1977, in press) docum ented the biasing effects of person schem as or 4‘p ro to ty p es” on the interpretatio n o f am biguous inform ation an d the recall of specific details about people. P erhaps the m ost en couraging developm ent for the question o f schem a arousal is the theoretical one in K a h n e m a n ’s and T v ersk y ’s w ork on heuristics. It is obvious that a schem a can be aroused only if it exists in the p erso n ’s long-term repertoire of schem as. W hat is not so obvious is that the acute or transient availability of a schem a also m ay be an im p o rtan t d eterm in a n t of its application to a p articu lar instance. T w o recent experim ents su p p o rt this possibility. H iggins, R holes, and Jo n e s (1977) asked subjects to read a b rief p arag rap h describing a young m an and then to evaluate him on a n u m b e r of dim ensions. T h e young m an was described as hav in g m any risky hobbies, having a high opinion o f his abilities, hav in g lim ited relationships w ith o th er people, and being unlikely to change his m ind or tu rn back from a chosen course of action. Before read in g ab o u t the y o ung m an , subjects h ad p ar36

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ticipated in a ‘ ‘learn in g ex p erim en t” in which some were exposed to the w ords “ a d v e n tu ro u s,” ' ‘self-confident,’‫ “ י‬in d e p e n d e n t,” and “ p ersisten t,” and some were exposed to the words “ reckless,” “ co n ceited ,” “ aloof,” and “ s tu b b o rn .” Subjects exposed to the positive w ords later evaluated the young m an m ore highly th an did those exposed to the negative words. (Subjects exposed to equally positive or negative b ut conceptually irrelevant words were unin flu en ced .) As H iggins an d colleagues suggest, this effect is most likely m ediated by the tran sien t availability o f different concepts or “ p erso n ae.” H o rn stein , L aK in d , F rankel, and M an n e (1975) perform ed an experim ent w ith sim ilar im plications. Before playing a p riso n er’s dilem m a gam e, subjects w ere left seated in a w aiting room listening to w hat they believed was a p ip e d ‫־‬in radio pro g ram . T h e m usic was in terru p ted for a “ h u m an in terest” story. In one instance this was a h eart-w arm in g account of som eone who offered a kidney to som eone w hom he did not know who was in need of a transp lant. In an o th er instance, subjects h eard a ghastly account of an u rb an atrocity. T h e vignette h ad p ro n o u n ced effects on subsequent strategy in the p riso n e r’s dilem m a gam e. Subjects who had heard the heart-w arm in g vignette played the gam e in a m uch m ore cooperative way than did those who had heard the h o rro r. T h e authors arg u ed persuasively (and with data) against a m ood in terp retatio n of the subsequent behavior. Instead, it seems likely th a t it was an acute m anip u latio n of the availability o f different personae or “ schem as for the h u m an ra c e ” th at accounted for the results ( “ m ost people are basically decent an d k in d ” versus “ it’s dog eat dog out th e re ” ). It seem s equally clear that the representativeness heuristic takes part in the selection of schem as. Indeed, the sim ilarity of the d ata at h an d to some stored rep resen tatio n of objects and events always has been presum ed to be the chief d eterm in an t of schem a arousal an d application. But it also seems likely th at purely incidental and irrelevant features of the stim ulus m ay p rom pt the arousal of schem as tagged with sim ilar incidental features. T h u s, we have it on the testim ony of Colonel H ouse (M ay 1973) that, on the eve of W orld W ar I, P resid en t W oodrow W ilson was anguishing over the possibility o f w ar w ith Great Britain. W hy? Because, as on the eve of the W ar of 1812, the British were illegally searching A m erican ships an d , as W ilson agonized to H ouse, “ M adison and I are the only P rinceton m en to becom e P resid en t” (!) A pparently, the “ search-ships/w ar with E n g lan d ” schem a was a representative one for W ilson in p art because o f the irrelevant surface detail of the alm a m ater o f the in cu m b en t president. A vailability and representativeness d eterm in an ts of schem a arousal appear to be the probable focal guides of future research in this area. It will be fascinating to see w hether these d eterm in an ts o perate in a norm atively app ro p riate w ay, or w hether, as in the W ilson anecdote, they operate so as to leave us at the m ercy o f a rb itrary and incidental features of stim uli and structures.

Appropriate and Inappropriate U tilization o f K now ledge Structures

It w ould be even m ore foolish to criticize peo p le’s general tendency to em ploy schem as an d o th er know ledge structures th a n it w ould be to criticize their general tendency to rely on the availability an d representativeness heuristics. Indeed, the p rim ary reason for the w idespread acceptance of the notion of schem atic know ledge structures is th at it is alm ost im possible to im agine how m ental life could be m anaged w ithout them . In a w orld characterized by recu rren t stim uli presen tin g im p o rtan t functional eq u iv alen ‫־‬ cies, any cognitive system that places a prem iu m on m inim izing co m p u tin g tim e and effort m ust take advantage of such red u n d an cy by storing generic concepts, events, event-sequences, an d the like. D espite the im p o rtan t efficiencies that accrue to the schem a user, there seems little doubt there often are serious costs as well. Schem as are apt to be overused and m isapplied, p articularly to the social sphere, an d they are apt to be used when other, less rap id an d intuitive m ethods of ju d g m e n t w ould fully m erit the additional tim e and effort req u ired . In the physical w orld, stim uli categorized in a p articu lar w ay, o r events in terp reted in term s of a given schem a, m ay be sim ilar to an extent rarely tru e in the social dom ain. In m any im p o rtan t respects, it is only a slight overstatem ent to say that “ if y o u ’ve seen one oak tree, y o u ’ve seen them a ll.” T h e n u m b er of properties necessary to define u niquely m an y types o f physical objects is highly lim ited. As a consequence, the n u m b e r of properties of a p a r ‫־‬ ticular object that m ust be perceived in o rd er to place the object in its correct category also is lim ited. M oreover, once a physical object has been placed in some conceptual category, one can usually disregard m uch of the inform ation that dictated the categorization (th at is, inform ation specifying exactly how , w hen, an d u n d er w hat observation conditions a p articu lar tree satisfied the requirem ents for assignm ent to the “ o ak ” category). M ost im p o rtan t o f all, classification of a physical object usually perm its one to adduce or predict confidently additional properties of the object. T h u s, once an object is correctly characterized as an oak tree, it is nearly certain th at the tree will provide shade and acorns, that its wood will be h a rd an d b u rn slowly, that all its leaves will drop in the fall, an d so on. It is quite different in the social d o m ain , in w hich the observed p roperties are less diagnostic, in w hich the n u m b e r of properties suggestive o f a given category are not so sharply delineated, and in which the n u m b e r of pro p erties that can be inferred confidently, given correct categorization of the object, is very small. T o appreciate these differences, let us note how the categorization of a person as a “ b ig o t” differs from the categorization of an object as an oak tree. First, the n u m b er of properties that m ight indicate bigotry is, for all practical purposes, infinite, and inform ation ab o u t the circum stances in 38

Judgmental Heuristics and Knowledge Structures

39

which a particu lar person satisfied the ‘‘b ig o t’’ criterion can be ignored or forgotten only at o n e ’s peril. Sim ilarly, the n u m b er of properties dictated by the categorization of som eone as a bigot is large only in p ro portion to the naivete of the perceiver. Few characteristics or behaviors can be confidently assum ed about any p articu lar “ b ig o t.” Schem as in the social dom ain rarely are m ore than rough outlines an d tentative guides for perception and behavior. W hen they are relied on heavily, there are b o u n d to be inferential errors and m isguided actions. E. R . M ay, in his fascinating book entitled “ Lessons” of the Past (1973), presented som e th o ught-provoking exam ples of erroneous political ju d g m en ts an d policies that seem to have orig in ated in the overutilization or m isapplication of p articu lar schem as. For exam ple, M ay describes how a schem a, which m ight be term ed the “ M u n ich C o n feren ce” script, ‫׳‬exerted an u n d u e influence on the th in k in g of politicians (m ost notably President L yndon Jo h n so n ), who invoked the specter o f the infam ous “ M u nich C o n feren ce” to defend the aggressiveness of their m ilitary policy o r the intransigence of their diplom acy. T hese politicians seem to have been influenced greatly by— or perhaps hoped to influence the public and their potential detractors th ro u g h — a particularly vivid, historic script. T h e script has two scenes or vignettes, ( variable. C orrelations betw een 0 and 1 req u ire that predictions give weight both to the score on the predictor variable and to the m ean o f the variable to be predicted, with the weight given to the predictor variable being a direct function of the correlation betw een the two variables. O n e im p o rtan t consequence of these norm ative statistical principles is th at, w ith decreasing diagnosticity of o n e ’s predictors, the range of o n e ’s predictions ought to “ sh rin k ” u n til, in the lim iting case of totally worthless predictor inform atio n , o n e ’s predictions ought to be the same no m atter w hat the score on the pred icto r variable. T h a t is, with a totally nondiagnostic predictor one ought sim ply to predict that every score will be equal to the m ean o f the outcom e distrib u tio n . T h is elem en tary review o f regression theory will be fam iliar to most readers, if not to m ost laypeople. B ut why ought one to “ regress” to the m ean in m akin g predictions? Essentially, one ought to do so because the m ean is the point in the d istrib u tio n closest to the largest n u m b er of observations. In other w ords, the m ean is a base line from which one should deviate only to the extent that the risks or costs of such deviations are likely to be com pensated by the diagnosticity o f the other in form ation one has ab o u t the target. T h e num erical prediction an d the category prediction cases thus are equivalent, and the tendency to be insufficiently regressive in num erical prediction closely corresponds, logically, to the tendency to ignore base rates in category prediction.

L aboratory D em onstrations o f N onregressive P rediction Strategies

T he layperso n ’s inability to recognize regression p h en o m en a (and the frequent inability of the sophisticated social scientist as well) is so fam iliar that we need not docum ent it at length. W e will focus on one of K a h n e m a n ’s and T v ersk y ’s (1973) m ore d ram atic illustrations o f the extent o f this failing. In this study, subjects were asked to predict the grade p o in t average (G P A ) of students based on one of three types of inform ation w hich had widely v ary in g predictive validity. T h e inform ation presented to som e subjects was the ta rg e t’s G PA expressed in percentile form , a virtually perfect p red icto r o f num erical G PA . T h e inform ation presented to a second group o f subjects was the ta rg e t’s score on a m ental concentration task, a fairly good b u t im perfect predictor. T he inform ation presented to a third group was a m easu re of sense of hu m o r, a very poor p redictor of G PA . Lest subjects be u n d e r any illusion, the experim enter specified that the relevant predictors w ere, respectively, perfect, good, or virtually valueless as predictors o f G PA . S u b jects’ predictions showed only the slightest hin t of regressiveness. Subjects tended to predict G P A scores that were as divergent from the m ean G P A as the predictor score was from its m ean, regardless of w hether the p redictor score was a perfect indicator, was m erely a good one, or was the nearly valueless sense of h u m o r score. Follow-up experim ents by A m abile (1975) an d R oss, A m abile an d J e n nings (1976) som ew hat extended and clarified K a h n e m a n ’s and T v e rsk y ’s findings. Ross and colleagues explored the prediction strategies of individual subjects by collecting a large n u m b e r of predictions from each p articip an t (in contrast to K a h n e m a n ’s and T v ersk y ’s (1973) procedure w hich used one prediction per subject). T h e investigators also used “ a u th e n tic ” d a ta distributions—derived from previous research reports, stu d en t records, self report questionnaires, and so o n — thus p erm ittin g direct assessm ent o f the degree o f accuracy and direction o f e rro r in the subjects’ estim ates. T h e re was little difficulty in replicating the basic phen o m en o n described by K ah n em a n and T versky. F or bivariate distributions in which population o r large sam ple correlations were in the range of r = 0 to r = + .30, the subjects m ade predictions that w ould have been justified only by correlations in the range of 60. + = ‫ ז‬to r = + 1 .0 0 . V ery few individuals system atically applied anything like a simple linear “ prediction e q u a tio n .” W hen subjects believed the relationship betw een variables to be strong, th eir in d ividual p redictions were often well m atched by a simple linear function, b u t w hen they believed the relationship to be w eak, th eir predictions varied widely a ro u n d any potential regression line. Specifically, w hen subjects believed the relationship between X and Y to be relatively w eak, they did n o t respond to extrem e values of X with predictions of Y that were consistently m oderately close to the 152

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m ean. In stead , they responded by varying the extrem ity of their predictions (for exam ple, by p redicting one very extrem e value of Y and one value of Y close to the m ean w hen given two identical values of the predictor variable X ). T h e d ata on accuracy also w ere revealing. T h e great m ajority of individual subjects w ould have decreased the m ag n itu d e of their errors by simply rep eatin g th eir average prediction for Y an d never varying it on the basis of their know ledge of the ta rg e t’s scores on X . T his result, in some respects, is rem iniscent of the tendency rep o rted earlier for useless diagnostic inform ation to dissuade subjects from using base rates in category prediction. It is difficult to resist concluding th at, w hen it com es to predictions, a little knowledge (that is, know ledge of the ta rg e t’s score on a weakly related predictor variable) is a d angerous thing. T hese studies indicated th at the tendency to be insufficiently regressive can be traced to two distinct sources. First, as we observed in chapter 5, peopie typically overestim ate the degree o f covariation betw een events in the social dom ain. T h ey do so, at least, when such events can be linked by plausible causal theories, scripts, or stereotypes. In this chapter, we have noted that people fail to m ake regressive predictions even w hen they recognize that the available predicto r variables are poorly correlated with the outcom e variable. T h u s, the failure to m ake appropriately conservative predictions is o v erd eter‫־‬ m ined. Incorrect theories of the strength of relationships in the social dom ain lead to exaggerated beliefs about the utility of various predictor variables, while intuitive prediction strategies result in nonregressive predictions even w hen the w eakness of the relationships is recognized.

A C on servative Self-im age for the R adical Predictor?

W e should note that although the intuitive scientist’s nonregressive prediction strategies m ay be labeled “ n o n co n serv ativ e,” this label m ay be m isleading w ith reg ard to the intuitive scientist’s own view of the strategy. Indeed, nonregressive predictions m ay result from a chain of inferences that seem im peccably ‘ 'conservative. ” C onsider, for exam ple, a request to predict J a n e ’s percentile score on a m athem atics test, given only the inform ation that she scored at the n inetieth percentile in a read in g test. T h e intuitive statistician m ay begin by recognizing that academ ic abilities tend to be positively correlated an d by reasoning th at J a n e ’s m ath score is likely to be b etter than average. T hese correct assum ptions m ay then flow readily, b u t treacherously, into the quite incorrect assum ption that, having no inform ation ab o u t J a n e ’s m ath score, there is no basis for predicting w hether it will be higher or lower th a n her read in g score. G iven such an assum ption it m ay thus seem conservative to guess that the m ath score will be equal to the reading score (a ju d g ­

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m ent that would be justified, in conventional statistical term s, only by a perfect correlation), for such a guess seem ingly represents the ‘‘m iddle course” betw een guessing either th at Y is higher th an X or th at Y is low er than X.

T H E D IL U T IO N EFFECT: PRODUCING “ REGRESSIVE” PR ED IC TIO N S BY EXPOSURE TO NONDIAGNOSTIC INFO R M ATIO N

T h e research to date indicates that peo p le’s predictions often will be very wide of the m ark . U n d er the conditions typified by the research, it seems clear that people com bine in fo rm atio n poorly for purposes of p rediction and usually fail to m ake predictions that reflect outcom e base rates and regression considerations. It is im p o rtan t to be specific ab o u t w hat those conditions are. Almost all research on prediction has been characterized by a p arad ig m in which subjects are given a small am o u n t of inform ation, all or m ost of which the subjects believe to be diagnostic. Typically, subjects are given info rm atio n about a target case in the form of values on one or m ore dim ensions. Som etim es these values are n u m erical values, as in m uch of the w ork in the M eehl tradition , and som etim es the “ v alu es” are verbal statem ents th at m ay be regarded as tacit “ scores” on som e outcom e-related dim ension. M any predictions in everyday life are conceptually identical to this research paradigm , from college student adm ission procedures to casual conversations in which one person sum m arizes a few “ diag n o stic” tidbits for another and then asks that person to m ake a prediction. M an y p rediction tasks, how ever, are im p ortantly different in th at the individual has m uch m ore inform ation about the targ et, including m uch inform ation of no diagnostic value w hatever. It w ould be interesting to know how people respond to a m ixture of diagnostic an d nondiagnostic inform ation in such inform ation-rich, com plex, prediction tasks. N isbett an d his colleagues (N isbett & Zukier 1979; Z ukier 1979; N isbett & Lem ley 1979) recently have begun to study predictions of this sort. It m ight well be expected th at such predictions would be even m ore inaccurate th an sim pler ones. S urprisingly, this appears not to be the case. In an initial ex perim ent, N isbett and Z ukier (1979) asked subjects to m ake predictions about the behavior of p articu lar m ale u n d erg rad u ates in two different psychological studies, a shock tolerance study an d a survey of m ovie attendance. Subjects were given various item s of in fo rm atio n ab o u t these “ ta rg e t” individuals, item s th at had been rated (by pretest subjects) either as highly “ diag n o stic” of probable behavior in the study or as totally “ n o n diagnostic.” Some subjects were presented only w ith a single diagnostic

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item — the targ et in d iv id u a rs m ajo r field of study. O th er subjects were presented with both the diagnostic item an d a series of nondiagnostic item s, such as the targ et in d iv id u a fs hom e tow n, religion, and so forth. As the read er should now be able to anticipate, the p resentation of a single £‘d iag n o stic’‫ י‬item led subjects to m ake extrem e (and w rong) predictions. Science m ajors were predicted to tolerate about twice as m uch shock as h u m an ities m ajors and to go to only about h alf as m an y movies. W hen the diagnostic item was accom panied by a set of nondiagnostic item s the result was quite different. T h e predictions for hu m an ities m ajors and science m ajors converged sharply. In o ther w ords, item s ju d g e d by pretest subjects to be worthless for purposes of prediction nevertheless served to “ d ilu te” dram atically the effects of an item ju d g e d to be highly diagnostic. In a follow-up study, N isbett and Lem ley (1979) found that as few as two w orthless item s of inform ation can dilute the effect o f one “ diagnostic” item . T h e subjects were social w ork graduate students who were instructed to estim ate the likelihood th at several social work clients, described by a small am o u n t of “ back g ro u n d in fo rm a tio n ,” were child abusers. “ D iagnostic” inform ation, for exam ple, th at the client was know n to have “ sadom asochistic sexual fantasies” , served to produce a strong presum ption that the client m ight be a child abuser. But th at d am n in g presu m p tio n was sharply reduced by the inclusion of the “ n o n d iag n o stic” inform ation that the client “ fixes up old cars in his spare tim e ” an d “ once ran aw ay from hom e as a b o y .” W ork by Z ukier (1979) indicated th at the dilution effect in no way refleets a general u n d erstan d in g of the principles of regression. Z ukier asked subjects to predict the grade point average of u n d erg rad u ate targets. W hen subjects had only “ d iag n o stic” inform ation, that is, an extrem e value on a dim ension believed to be correlated w ith G PA , subjects m ade extrem e, nonregressive predictions. W hen they were given average values on each of several o ther dim ensions, they “ reg ressed ” th eir predictions alm ost back to the m ean. But they did so to precisely the sam e extent w hether they believed th at each o f the “ d ilu tin g d im en sio n s” was highly correlated with G PA or believed th at each of the dim ensions was uncorrelated with G PA . (T he regressive predictions w ould have been quite justified in the form er case of high correlation b u t quite unjustified in the latter case since the low correiation of the dim ension w ith G PA m ade these values, w hether average or otherwise, irrelevant to predictions.) In in terp retin g the “ dilution effect” N isbett an d Z ukier (1979) relied on T v e rsk y ’s (1977) analysis o f sim ilarity ju d g m e n t. T h ey argued th at nondiagnostic inform atio n ab o u t the target person, though logically irrelevant to the prediction task, has the capacity to ren d er the target person less “ sim ilar” to th at hypothetical individual who m ight be m ost likely to exhibit extrem e an d atypical responses. It is these simple sim ilarity or “ rep resen tativ en ess” ju d g m e n ts, ra th e r th an m ore norm atively ap p ro p riate strategies, th at

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underlie the su b ject’s predictions. T his arg u m en t (which hinges upon T v ersky’s theoretical assertions ab o u t the role of “ c o m m o n ” an d “ n o n c o m m o n ” features in sim ilarity ju d g m en t) is rath e r com plex an d need not concern us fu rth er here. W h at does concern us, how ever, are the im plications of the dilution effect for everyday accuracy in prediction. T h e dilution effect findings are, in one sense, hopeful in th at they suggest that predictions in m any everyday life situations m ay be m ore “ reg ressiv e” than past research has im plied. T h ey w ould be m ore hopeful if they pro v id ed any indication that such relatively accurate predictions reflected any u n d erstan d in g o f the norm atively correct approach to prediction. T h e findings provide no such indication, n o r does any o ther research th at we can report. T h ere is some research, how ever, w hich, like the dilution effect findings, indicates that predictions will som etim es be regressive in form , if not in spirit. T h e circum stances that m ay occasion such relatively accurate strategies are discussed next.

C IR C U M S T A N C E S P R O M P T IN G T H E U T I L I Z A T I O N O F BASE R A T E S IN P R E D IC T IO N

T h ere are several kinds of evidence suggesting that people do som etim es give prior probabilities or base rates considerable, even ad eq u ate, w eight in category prediction. T h ere is even evidence suggesting th at people occasionally appreciate the wisdom o f regressive predictions in problem s involving continuous variables. As research in this area has expanded, it has becom e clear that there are at least three circum stances th at prom ote the use of prediction strategies that conform reasonably well to no rm ativ e dictates.

Lack o f A lternative P rediction Strategies

It is obvious from both lab o rato ry research and everyday experience th at w hen m eans, base rates, or p rio r probabilities are the only in fo rm atio n available, people seem quite able to recognize the significance of such inform ation and to m ake ap p ro p riate use o f it. T h u s, subjects asked to guess the height, IQ , o r h air length o f an individual ab o u t w hom n o th in g else is know n are apt to rely on th eir guesses of relevant population m eans. S im ilarly, subjects told only that an individual has been random ly sam pled from a population consisting o f 70 percent engineers and 30 percent law yers recognize th a t the sam pled individual will, in fact, be an en g in eer 70 percent of the tim e. W e also have no doubt that people w ould predict th at a random ly selected citizen is m ore likely to be a M r. T ay lo r th an a M r. Shoem aker, is m ore likely to be

Prediction

15 7

a native of C alifo rn ia th an of N evada, and is m ore likely to be a Presbyterian th a n a D ru id . In fact, there can be little doubt that the layperson possesses and uses the general predictive schem a that, other things equal, m ore n u m ero u s outcom es are m ore likely to occur or to be sam pled than less n u m ero u s outcom es. At the sam e tim e, it is also im p o rtan t to reiterate the lay p erso n ’s d em o n strated willingness to disregard base-rate inform ation when there is the slightest o p p o rtu n ity to utilize any other strategy. In fact, once the form of a prediction problem invites the layperson even to consider potentially diagnostic inform ation about the targ et, utilization of the base rate does not seem to serve even as a strategy of “ last reso rt” should the target inform ation prove valueless. Recall th at the subject in the K ah n em an and T versky (1973) studies who was given both base-rate inform ation and valueless target-case inform ation was apt to ignore both types of inform ation and act as if there were no basis w hatever for m aking a prediction. Indeed, the subject asked to predict the behavior of “ a college sophom ore nam ed J o e ” in a p articular psychological experim ent, m ay largely ignore b ase-rate inform ation about the overall distribu tio n of responses shown by participants in the experim ent. T h e subject m ay rely instead upon (erroneous) intuitions about how a “ ty p ical” particip an t ought to act. H av in g decided that n either the status “ so p h o m o re” nor the nam e 4‘J o e ” are sufficiently diagnostic, the subject responds as if intuitions about typical college student behavior are m ore useful for m aking predictions th an b ase-rate inform ation that happens to contradict those intuitions. D ata showing that subjects m ake m inim al use of the behavioral base rate w hen given such scant and w orthless target-case inform ation m ay be found in a study conducted in 1977 by W ells and H arv ey (though the authors chose to em phasize the fact that such inform ation was used at all).

T he Use o f C ausally R elevant Base Rates

T h ere is a second and far m ore significant class of problem s in which base rates are ap p ro p riately utilized. C o n sid er the behavior of a person asked to assess the likelihood th at the next card dealt will be an ace or th at the next roll of a single die will produce a six. W e have very little doubt that, on the average, p eople’s estim ates will be quite close to the “ co rrect” probabilities of o n e-th irtee n th and one-sixth, respectively. W e suspect that the additional inform ation th at the dealer is nam ed T o m , has five children, wears argyle socks, an d subscribes to Readers' Digest, will not preem pt reliance on these fam iliar base rates. W hy are such base rates utilized so faithfully? T h e re m ay be several reasons. T h e base rates are well rehearsed and are not co u n terin tu itiv e. T h e dom ains, fu rth erm o re, are ones in which po p u lar scripts and m axim s describe

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the folly of “ disregarding the o d d s .” M ost im p o rtan t of all m ay be th at the relevant base rates seem consistent with a causal theory. T h a t is, people can app re d a te the generating function pro d u cin g the outcom es and hence the probabilities u n d er consideration. R ecent studies by A jzen (1977) and T v ersk y and K ah n em an (1978) have illustrated the im portance of such causal theories in d eterm ining people’s willingness to use base-rate inform ation. In A jzen’s study, subjects were asked to assess the pro b ab ility th a t a given student, whose level of effort, intelligence, and m otivation w ere described in a brief sketch, h ad passed a p articu lar scholastic ex am in atio n . All subjects were provided w ith base-rate d ata on the percentage of passes an d failures in the sam ple from which that student allegedly was selected. Specifically, all subjects were told that 75% , o r only 2 5 % , of the students in the relevant sam ple had passed the course. In one condition, the “ non-causal” base-rate condition, the subjects were told that p ercentage of passes vs. failures in the sam ple reflected the inv estig ato rs’ deliberate decision to sam ple prim arily successes (or p rim arily failures) because that was the outcome in which he was most interested. Subjects in this condition gave very littie weight to the base-rate in form ation in m aking their estim ates; instead, they estim ated the probability th at the student h ad passed the course to be high or low almost entirely on the basis of the in form ation provided in the personal description. In a second condition (the “ cau sal” base-rate condition) the subjects were told simply th at 75% , or only 2 5 % , of the students enrolled had passed the course, thereby suggesting that the specified base rate reflected the ease or difficulty of the test. In this condition, by contrast, subjects m ade very substantial use of the base rate, and th eir probability estim ates ab o u t the stu d e n t’s outcom e in the course gave only m oderate w eight to the in fo rm atio n provided about his intelligence, effort and m otivation. In su m m ary , the subje c ts ’ willingness to utilize a base rate was determ in ed by the presence or absence of a clear indication of the cause of th at base rate. If the base rate could be interpreted as reflecting causal influence, for exam ple that of test difflculty, it was utilized very heavily; if the base rate reflected only “ a rb itra ry ” group com position, it was utilized only slightly. A n equally im pressive d em o n stratio n of the sam e p h en o m en o n , one offering striking evidence of a n orm ative violation on the part of subjects, was reported by T versky an d K ahnerrian (1978). T hese investigators told their subjects that in a p articu lar tow n there were two cab com panies, the Blue C o m p an y and the G reen C o m p an y . T h ere h ad been an accident involving a cab, and subjects were to ju d g e the likelihood that the cab h ad been blue, as opposed to green. T h ey were to do so on the bases of an im perfect eye w itness identification, coupled with some inform ation about base rates. T h e relevant base rate was m an ip u lated in one of two ways. Some subjects were told th at 85 percent of the to w n ’s cabs were blue and 15 p ercen t were green. T hese

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subjects largely ignored the base rates provided, and instead based th eir ju d g m e n ts prim arily on the reliability of the eye w itnesses’ color identifications. O th e r subjects were told that though the tow n had an equal n u m b er of blue and green cabs, 85 percent of the cab-related accidents involved blue cabs w hereas only 15 percent involved a green cab. T hese subjects relied heavily on the base rate. N orm atively, the relevance of the base rate would seem to be the sam e in the two conditions; yet it was only w hen the base rate could be given a causal in terp retatio n , p ertain in g to careless versus careful driv in g tendencies, th at it was utilized substantially. It appears th at w hen base rates can be given a causal in terp retatio n , they will be reflected in predictions. T h o u g h peo p le’s use of causally interpretable base rates is based on a norm atively questionable distinction, they do at least possess a strategy that will generate reasonably accurate predictions in some instances.

C on cretizin g the Base Rate

A n o th er cure for people’s base-rate blindness is im plicit in N isb ett’s and B o rg id a’s (1975) analysis of one of the chief causes for the blindness, the fact th a t base-rate d ata usually are dull and u n in terestin g . If the base rate were presented in a m ore concrete and vivid way than has been done in m ost of the research, it seems likely that it w ould have m ore influence on ju d g m en ts. A necdotes and th o u g h t experim ents suggest that concretized base rates do have som e influence. A fledgling auto m echanic, inform ed that only about 70 percent of the rep air sh o p ’s efforts are successful on the first attem p t, nevertheless m ay send his first dozen cars out of the shop convinced that the problem has been solved in every case. As the con trary evidence m ounts up, it seems likely that the m ech an ic’s confidence in each individual rep air jo b will decline. Sim ilarly, young couples m ay assum e that the divorce rates have little relevance to people like them selves and th eir friends. As reality intrudes, w ith its concrete evidence that divorces occur also am ong their set, they m ay becom e less convinced of the durab ility of their frien d s’ m arriages, and even of th eir own. W ork by M anis and D ovalina (1979) indicated that these suppositions are well founded. T hese investigators asked subjects to m ake predictions of the attitu d es (for exam ple, tow ard m a riju an a legalization) of college students whose photograp h s they w ere shown. Subjects in feedback conditions were told, after each guess, w hat was the ‘‘ac tu a l” attitude of the student. For some subjects, the feedback indicated an 80 p ercen t‫־‬pro/20 p ercen t-an ti patte rn , while for o ther subjects the p attern was reversed. T his concrete, exp eriential m a n ip u latio n of base rate was highly influential. Subject p red ic­

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tions cam e to m atch the base rate. Such a ‘‘p ro b ab ility -m atch in g ’’ ap p ro ach does not m axim ize “ h its ,” b u t it does result in m uch m ore u tilization of base rate th an com m only results from dull, one-shot, d ata sum m aries. T h e evidence suggests th at, although people lack an intuitive u n d erstanding of Bayesian principles of prediction, th ere are several circum stances in which predictions will be m uch less im paired th an m ight be im plied by such a failure. If no other inform ation except base rate can be invoked, if the base rate has a causal in terp retatio n , o r if the base rate is correctly experienced, predictions are likely to be m uch m ore accurate th an they are u n d e r o th er ju d g m en t conditions.

REGRESSION PH ENOM ENA: OCCASIONAL RECOGNITION AND CHRONIC M ISCO NSTRUAL

J u s t as people recognize an d use base rates in som e specific contexts, they often are able to recognize specific regression p h enom ena. As we shall see, such insights do not seem to be the p roduct of any general u n d e rsta n d in g o f the n atu re of regression. T h a t is, people fail to ap preciate th a t regressiveness in the overall relationship of the fu tu re to the p resen t, the whole to the p art, o r the unknow n to the know n, occurs because (an d to the extent that) the two m easures u n d e r consideration are im perfectly correlated w ith each other. T h is lack of insight, it should be em phasized, applies not only to form al m athem atical statem ents or to regression eq u atio n s, b u t to their everyday verbal equivalents as well. T h u s, the layperson does not seem able to articulate or utilize, an d m ay even disagree w ith, propositions of the following sort: — Events th at are extrem e on some dim ension will, on the average, be less extrem e w hen they recur, w hen they are reassessed, o r w hen they are assessed on any oth er dim ension. — Events or objects th at ap p ear to be extrem e on som e dim ension on the basis of prelim inary inform ation or on the basis of a lim ited sam ple of evidence, will, on the average, prove to be less extrem e w hen all of the relevant evidence becom es available. It is true th at there are some general cultural m axim s that seem to reflect a recognition of regression p h en o m en a. ( “ A b ird in the h an d is w orth two in the b u s h ;‫ “ יי‬T his too shall p ass;” “ Y ou c a n ’t tell a book from its c o v e r.” ) T hese m axim s, how ever, are not stated in term s th at help the layperson recognize their general applicability in all circum stances in which covariation is im perfect. T h e m axim s also lack any h int th at predictions should give weight to the “ central ten d en cies” of the outcom e dim ension an d certainly do

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not convey instructions to be regressive as a function of the strength of the relationship betw een target indicators and outcom e values. F u rth erm o re, they are contrad icted by o ther m axim s that we suspect are far m ore com m on, that m ay ap p ear equally wise an d that tend to u n d erm in e com prehension of regression p h en o m en a. ( “ As the twig is b en t, so grows the tre e ,” “ As ye sow, so shall ye r e a p ,” “ A chip off the old b lo ck ,” “ Birds of a feather flock to g e th e r.” ) A lthough a general ap preciation of regression phen o m en a is rare am ong lay observers, there are m an y instances in which the in d iv id u al’s experience, or collective w isdom culled from the experience of m any individuals, does lead to predictions th a t ap p ear regressive. In such cases, how ever, u n p arsim onious theories and in ap p ro p riate scripts often are invoked both to “ exp la in ” individual cases of regressiveness and to account for regression p h en o m en a w ithin p articu lar dom ains of experience. Indeed, as will be clear from some exam ples, even statistical sophistication bestows an im perfect protection from such failings.

A ssessm ents o f Professional P otential

A lm ost all academ icians recognize, o r soon com e to realize on the basis of painful experience, th a t the m ost talented g rad u ate students will only seldom prove to be equally o u tstan d in g professionals. T h e academ ician usually can offer a host of theories or scripts to account for such disappointm ents. He was good at executing research but didn't really have any ideas of his own. She had all the ability in the world but lacked the necessary drive and aggressiveness. He let himself get bogged down in administrative responsibilities. She settled for the gratifications of being a popular lecturer. He just didn’t get the necessary moral support and guidance from his colleagues. W hat such an academ ician fails to recognize is that this dom ain is sim ply one in w hich the p red icto r variables (accom plishm ent an d talent shown in g rad u ate school) are im perfectly correlated with the outcom e variable (professional achievem ents). T h u s, the u n spectacular perform ance of m any highly touted new professionals is sim ply an o th er regression phenom enon. A d hoc ex p lan ato ry theories, like those described, obscure the fact th at such disapp o in tm en ts are the rule an d not the exception. Indeed, m ost such “ explanatio n s” are probably best reg ard ed sim ply as an account of some of the sources of the im perfect relationship th at exists betw een predictors and outcom e. Like postgam e analyses by coaches whose team s have lost, they are accounts of “ h o w ” and not “ w hy” a statistically likely event has occurred.

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T he m irro r im age of this m isu n d erstan d in g of regression p h en o m en a is that the very best professionals are often a ‘‘pleasant su rp rise ;” they have proved to be relatively more successful as professionals th an they had been as graduate students, surpassing peers who once had seem ed b etter prospects. A gain, explanations for these pleasant surprises are easy. State U. turned out to be very good for her. What he really needed was the competition he got at Ivy U. When you think about it, she always was a slow starter. All he needed to take off was independence from his advisor. T he readiness with which the “ ano m alies” are explained preem p ts the possibility of recognizing that the entire array of outcom es, including both pleasant and the unpleasant surprises, are inevitable u n d e r conditions of im perfect predictability. W hat are the consequences of m isconstruing predictable regression effects in academ ic accom plishm ent as causally explicable exceptions? Som etim es, the only cost is an unnecessary ex penditure of intellectual energy and the risk that a colleague will smile and ask “ have you ever h eard of regression effects?” Som etim es the costs are far m ore substantial. O n e search com m ittee with which we are fam iliar reasoned that since the best g rad u ate students are usually disappointm ents and since the best professionals are often dark horses, the d ep artm en t should largely ignore the letters o f recom m endation and publication records that cu rren tly serve as o u r predictors and sim ply search for congenial people with interesting o r offbeat research interests. A nother com m ittee is plagued by suggestions to use “ persona m a tc h in g ” as a search strategy; for exam ple, “ L e t’s find som eone who looks the way J a n e S him m er, o u r rising d ep artm en tal star, did as a g rad u ate stu d e n t” (th at is, cautious letters of recom m endation, two or three publications, b u t a high energy level and a sm ashing “ jo b ta lk ” ). C orrectly labeling the relevant ph en o m en a as instances o f predictable regression should help to prevent such folly. W hile it is ap p ro p ria te to be conservative in o n e ’s predictions or expectations of o u tstan d in g prospects, such conservatism hardly justifies ignoring p red icto r variables or settling for m oderately positive values o f these variables w hen extrem ely positive values are available. T his is particularly im p o rtan t w hen o n e ’s concern is m axim izing the likelihood of selecting exceptionally able candidates. C o n sid er, for instance, a case in which o n e ’s set o f pred icto r variables correlates w ith the relevant outcom e variable at a m odest level (for exam ple, r = .33). A n exceptional candidate (for exam ple, one who is three stan d ard deviations above the m ean on the set of predictors) is, on the average, apt to be only a m oderately successful professional (one stan d ard deviation above the m ean). N evertheless, if Sm ith is three stan d ard deviations above the m ean on the set

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of predictors while Jo n e s is only one stan d ard deviation above, Sm ith is an ord er of m agn itu d e m ore likely to prove an exceptional professional than J o n e s is. Specifically, using conventional linear regression com putational form ulas, S m ith is m ore th an seven times as likely as Jo n es to be three standard deviations above the m ean in professional accom plishm ent. In sum m ary , the m isu n d erstan d in g o f regression phenom ena can result in unrealistic expectations and ill-advised policies, both of which could be prevented sim ply by recognizing the everyday relevance of the regression principles taug h t in in tro d u cto ry statistics courses.

A ssessing the Effects of Personal and Social In terven tion s

T h e failure to label regression ph en o m en a correctly can have im p o rtan t consequences w henever the observer notes the ap p aren t covariation betw een changes in personal or social outcom es and the introduction, by accident or design, o f factors that m ight plausibly influence such outcom es. K ah n em an and T versky (1973) provided a parad ig m atic illustration of the superstitious beliefs that can result from failure to recognize simple regression phenom ena. Israeli flight instructors had been urged to use positive reinforcem ent and to avoid negative reinforcem ent in shaping the perform ance o f pilots attem p tin g to m aster difficult flight p attern s an d m aneuvers. A fter following this practice for a while, the instructors expressed skepticism about the wisdom o f such a strategy. In their personal experience, they arg u ed , praise of exceptionally good perform ance typically led to dim inished perform ance on the next trial, while criticism of an exceptionally poor perform ance typically produced an im m ediate im provem ent. T h e instructors were so im pressed with this phenom enon th at they even challenged the m ore general psychological doctrine that had been presented to them . P u n ish m en t, they concluded, was m ore effective th an rew ard in shaping desired behavior. W e suspect th a t such m islabeling of simple regression phenom ena (w hereby extrem ely good or bad perform ances will, on the average, be followed by less extrem e perform ances w henever there is an elem ent of chance in such perform ances) is com m on in everyday experience. O ne disconcerting im plication of such m islabeling is th a t m easures designed to stem a ‘‘crisis’’ (a sudden increase in crim e, disease, or ban k ru p tcies, or a sudden decrease in sales, rainfall, or O lym pic gold m edal w inners) will, on the average, seem to have g reater im pact th an there actually has been. Illusions o f personal or social control are likely to result, p articularly w hen a causal influence o f the various interventions or incidents can be inferred on the basis of plausible theories.

E x p la in in g th e “ S o p h o m o r e S lu m p ”

T h ere are some dom ains in w hich, we suspect, even the m ost sophisticated scientist is guilty of developing causal explanations for sim ple regression phenom ena. C o n sid er, for exam ple, the oft-cited “ sophom ore slum p” fam iliar to baseball fans, even fans who h ap p en also to be scientists fam iliar w ith the use and in terp retatio n of statistics. A sensational rookie hits hom e runs or pitches shutouts at such a rate that everyone is convinced th at he is b ound to be a su p erstar for the next decade. In the next year, how ever, the young sensation suffers a serious “ slu m p ” in p erform ance. T h e phenom enon is fam iliar to all who w atch the sport, an d the explanations for the phenom enon are equally fam iliar. ( “ Success an d fam e spoiled h im ” ; “ T h e pitchers/hitters m ade the necessary ad ju stm en ts” ; “ H e pressed too h ard, stopped w orking as h ard , gained w eight, lost w eight, got m arried in the off-season, got divorced in the off-season.” ) In d eed , the v eteran sports fan m ay simply cite the sophom ore slum p as cause enough! W hat is seldom recognized is that simple regression principles g u aran tee that, by chance alone, some m ediocre athletes will perform exceptionally well in their first year b u t perform less well in subsequent years. Since the relevant outcom es (hom eruns, strikeouts, and so on) are statistically relatively unreliable phenom ena, these regression effects are b o u n d to occur. In o th er w ords, the best explanation for a sophom ore slum p is th at the first year was atypical for the perform er in question while the second year showed regression tow ard his “ tru e ” ability level or perform ance base line. If the read er doubts this in terp retatio n we invite consideration of the following two facts: First, so-called sophom ore slum ps seem to be far m ore com m on in athletic events in which there is unreliability an d instability in perform ance than in events in which there is great reliability. F or exam ple, weightlifters and ru n n ers seem to show d ram atic slum ps far less often th an baseball players do. Second, an exam ination of star ballplayers (for exam ple, those who were ultim ately inducted into the H all of Fam e) shows no sign of sophom ore slum ps. F or these perform ers, strong first-year-perform ances reflected the athletes’ long-term ability, rath e r th an “ c h a n c e ,” so there should have been no regression. W e need not belabor the point. T h e sophom ore slum p is sim ply (or, at least, largely) a specific instance of the general regression principle th at, on the average, extrem e first observations of an unstable p h en o m en o n are typically m ore extrem e than subsequent ones. W hile careful d ata collection and analysis would be req u ired to prove the p o in t, we suspect th at equivalent “ slu m p ” phenom ena occur in other dom ains and are equally likely to be m islabeled. For instance, the theory that academ ic ten u re (or, for th at m atter, the Nobel Prize) reduces subsequent productivity eith er in specific cases or “ in g en era l,” is likely to be offered to explain a sim ple regression 164

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phenom enon. Sim ilarly, superstitions about w hat one m ust change to end a bad streak ” of outcom es, or m ust not change for fear o f ending a “ good s tre a k ,” will arise from the observation o f simple regression phenom ena. P eo p le’s failure to recognize regression ph en o m en a for w hat they are appears to be inevitable, given that intuitive strategies of prediction utilize principles that resem ble only tangentially the ap p ro p riate statistical strategies. W hile predictions m ay often be passably accurate in daily life, they often will be quite inaccurate. E qually serious is the fact th at people often will think that they can explain and control events that are largely chance determ ined and conversely will ascribe to caprice m any events which really are m odestly predictable.

SUM M ARY

People perform m any prediction tasks quite poorly both in the laboratory and in everyday life. T h is is true in p art because people do not u n d erstan d fu n d am en tal statistical principles, notably the principles of regression, essential to norm atively ap p ro p riate prediction strategies. People do not seem to utilize population base rates in m any prediction tasks and instead greatly overutilize the representativeness heuristic; that is, they m atch the features o f the target w ith those o f the outcom e and predict that the target will have the outcom e to the extent that the target resem bles the outcom e. Sim ilarly, people m ake generally nonregressive predictions for continuous variables. T h ey tend to predict th at the target will be as extrem e on the outcom e dim ension as it is on the p redictor dim ension. T h e representativeness heuristic paradoxically m ay produce relatively accurate, “ regressive” predictions if people possess nondiagnostic inform ation in addition to diagnostic in fo rm atio n . In that case, the nondiagnostic inform ation appears to “ d ilu te ” the im plications of the diagnostic inform ation, with the result th at predictions are less extrem e than they would have been if based on diagnostic in fo rm atio n alone. In addition, though people do n o t u n d erstan d the basic probabilistic principles of prediction, they do som etim es utilize base rates. T h ey seem to do so w hen: (a) No target info rm atio n is available which can encourage utilization of the reprsentativeness heuristic; (b) base rates m ay be given a causal in terp reta tio n ; or (c) base rates are “ co n cretized ” th ro u g h feedback ab o u t p articu la r m em bers o f the population. T h o u g h people have a ru d im en tary u n d erstan d in g o f regression effects in som e p articu la r dom ains, their lack of generalized appreciation of the regression concept exposes them to serious m isu n d erstan d in g of the n atu re of other dom ains. T h u s, people offer special-purpose causal explanations of

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events that are m ore properly understood as a sim ple consequence of regression. Such ad hoc explanations leave their illusions of near-perfect predictability intact and set them up for fu rth er, continual surprises. Sim ilarly, illusions of control are sustained because im provem ents in tem p o rarily m alfu n ctio n in g social system s or processes, which are actually d ue to regression, are attrib u ted instead to purposeful interventions.

8 theory maintenance and theory change

The human understanding when it has once adopted an opinion draws all things else to support and agree with it. And though there be a greater number and weight of instances to be found on the other side, yet these it either neglects and despises, or else by some distinetion sets aside and rejects, In order that by this great and pernicious predetermination the authority of its former conclusion may remain inviolate. Francis Bacon,

Few critiques of h u m an ju d g m en tal failings ring as true as B acon’s (1620) attack on peo p le’s tendency to adhere to a preconceived belief in the face of evidence that ought, rationally, to weaken or even reverse the belief. Each of us is confronted alm ost daily with the perversity of those who persist in their m isguided political, social, and scientific beliefs even after we have inform ed them of the facts. P eople’s readiness to cling to discredited beliefs is a constant, depressing rem in d er that m ost people are less intelligent, less objective, and less com m itted to the tru th than we ourselves are! E m pirical research and philosophical analysis since the tim e of Bacon have tended to support B aco n ’s critique. W ork by Luchins (1942, 1957) and by the H o vland group (for exam ple, H ovland, J a n is, & Kelly 1953) showed that opinions, once form ed, are slow to change in response to new evidence. O th e r investigators have dem o n strated the rigidity of theories and beliefs in their studies of attitu d e form ation (Asch 1946; Edw ards 1968), post decisional ju d g m e n ts and attitu d es (F estinger 1957; J a n is 1968), and the m aintenance of 167

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racial, ethnic, religious, and sex-role stereotypes (A llport 1954; 1 aynor & D eaux 1973; G oldberg 1968; J . Jo n es 1972; K atz 1960). Scientists them selves have been a chief target of such criticism . T h e tendency of professional scientists to persist in adhering to theories well past the point at which such adherence can be justified by the evidence has been observed by m any (for exam ple, B arber 1952; K uhn 1962; M ahoney 1976, 1977; M ah o n ey & D eM onbreun 1977; M cG uigan 1963). U nbridled em piricism in the doctrinaire positivist trad itio n , on the o ther hand, also has had its critics (for exam ple, Polanyi 1958, 1964). T hese authors, like K u rt Lew in, have em phasized the practicality of theories. Theories are useful because they stru ctu re knowledge into coherent wholes, organize experience, and facilitate supplem entation of the data given with inform ation that can be retrieved readily from m em ory. T h e im plication of this position is that conservatism with respect to theories is often advisable. N either the layperson nor the scientist should readily dispose of a wellestablished theory because it happens to conflict with some new evidence. It is often proper to look askance at, or even to totally ignore, reports of virgin births or new cancer cures. It m ay even be p roper to dismiss evidence collected by reputable scientists if it conflicts with some pow erful, parsim onious and integrative theory (Polanyi 1958). T he central question of this chapter directly parallels one discussed in chapter 4. In that chapter, we discussed the extent to which peo p le’s theories influence their characterization of data. In this chapter we discuss the extent to which data forces the revision of theories. O u r conclusion about the form er question, in chapter 4, was that characterizations of data are very heavily influenced by theories but that this is norm atively ap p ro p riate, at least for most inferential tasks encountered by the practitioner and the layperson. We now m ust qualify that conclusion by pointing out that assimilation of data to preexisting theory is norm atively app ro p riate only if it is accompanied by adequate accommodation of the theory to the im plications of the new data. If theories change sluggishly or not at all in response to data th at ought to force their revision, then this is dangerous precisely because it w ould m ake a m ockery of the practice of perceiving new data through the filter of a theory. T h e picture that would em erge, if Bacon and com pany are correct, is that of an intellectual B ourbon— a person whose u n d erstan d in g of the w orld, no m atter how erroneous, cannot change, because relatively am biguous data are interpreted in light of a theory while relatively u n am b ig u o u s data contrad ictin g the theory force little or no revision of the theory. T he question thus is of critical im portance: Do o u r theories change in response to new data as m uch as norm ative standards require? W e already presented some evidence on this question in ch ap ter 5, w hen we dealt with the degree to which people’s theories about covariation responded to actual data

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on covariation. W e concluded th at such theories generally were alm ost im pervious to d ata an d that people who subscribe to a given covariation theory before en co u n terin g evidence th at should have served to o v ertu rn the theory, often em erge from such encounters w ith the theory unblem ished and unscathed. It could be arg u ed that this occurs m erely because people have little ability to perceive covariation accurately and th at the picture m ight be different for other kinds of theories. U n fo rtu n ately , we cannot be so optim istic. W e believe that the lesson of ch ap ter 5 is a general one an d th at Bacon is correct: People seem to persist in ad h erin g to th eir theories to a point that far exceeds any norm atively justifiable criterion of ‘'conservatism . ” Ross an d L epper and their colleagues have given this tendency the pejorative label "b e lie f p ersev eran ce.’’ T h eir w ork, together w ith some older work in the literatu re on im pression form ation, supports three hypotheses about perseverance of belief. 1. W hen people already have a theory, before en co u n terin g any genuinely probative evidence, exposure to such evidence (w hether it supports the theory, opposes the theory, or is m ixed), will tend to result in m ore belief in the correctness of the original theory than norm ative dictates allow. 2. W hen people approach a set of evidence w ithout a theory and then form a theory based on initial evidence, the theory will be resistant to subseq u en t evidence. M o re form ally, peo p le’s response to two sets of evidence w ith opposite im plications does n o t adhere to the com m utativity rule which dem ands that the net effect of evidence A followed by evidence B m ust be the sam e as for evidence B followed by evidence A. 3. W hen people form ulate a theory based on some putatively probative evidence and later discover th at the evidence is false, the theory often survives such total discrediting.

OLD TH EO R IES AND NEW EVIDENCE

E veryday experience dem onstrates th at people often do not believe evidence that opposes some theory they hold. If the evidence cannot be discredited o u trig h t, it m ay nevertheless be given little weight and treated as if it were of little consequence. T h u s, the theory often survives intact new data w hich ought, superficially, to force revision of confidence in the theory or perhaps even to reverse the theory. As m any analysts have noted how ever, such conservatism often m ay be well advised. Even if one cannot recall the evidence from which the theory was originally derived or the m ore general beliefs from which the theory was deduced, this does not m ean th at the evidence does not exist or that there is not a w ell-justified arg u m e n t leading

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from m ore general propositions to the cu rren t specific one. It m ay m ean only that we cannot currently recall such evidence or the logic from w hich we inferred the view we now hold. T h o u g h a certain hesitancy in ap proaching new evidence m ay be justified, it is difficult to rationalize certain types of response to new evidence. An experim ent by L ord, Ross, and L epper (1979) shows that people s response to new evidence som etim es m ay be quite in ap p ro p riate. T h ey presented two purportedly au thentic studies on the d eterren t effects of capital punishm ent to S tanford U niversity students who h ad indicated previously either that they strongly believed capital p u n ish m en t to be a d e te rre n t to potential m urderers or strongly believed it to be w orthless as a d eterren t. In a counterbalanced design, each subject read first ab o u t the results an d m ethod of an em pirical study that supported their own position and then ab o u t the results and m ethod of a study that opposed it, or they read first ab o u t an opposing study an d then about a su p p o rtin g one. For all subjects, one of the studies h ad a “ p an el” design, com paring m u rd er rates for states before and after adoption of capital pun ish m en t, and the oth er study had a “ c o n c u rre n t” design, com paring m u rd er rates d u rin g the sam e tim e period for states w ith versus those w ithout capital p u n ishm ent. For half of the subjects, it was the panel design study that supported their position an d the co n cu rren t design study that opposed it, an d for the o ther half of the subjects it was the reverse. W as the sym m etry in probativeness and im plications of the evidence reflected in a com parable sym m etry of beliefs about the d eterren t effect of capital punishm ent? It was not. 1. Subjects found w hichever study su p p o rted their own position to be significantly “ m ore convincing” an d “ b etter co n d u cted ” than the study opposing their position. If it was the panel study that su p p o rted th eir position and the concurren t one that opposed it, the subjects could see clearly the superiority of a panel design, in which a state was com pared w ith itself before and after introduction of capital p u n ish m en t, over the sloppy technique of the concurrent study which com pared, say, bucolic N o rth D akota w ith u rb an ized New Jersey . If it was the co n cu rren t study that su p p o rted th eir position, the subjects could readily appreciate the wisdom of a design th at held tim e perio d constant, an d found no trouble in exposing the flaws in a design th a t compared one state with itself, to be sure, b u t allowed everything else to vary w ithout control, including tem poral changes in the dem ographic com position of the state, changes in conviction rates an d parole procedures, and the like. T h e subjects thus treated the evidence in a highly asym m etric way: Supportive evidence was handled w ith kid gloves; opposing evidence was m a u le d .1 2. T h e design of the study m ade it possible to evaluate attitu d e change at 1 Any resemblance between the behavior of subjects in this experiment and that of any professional scientist, living or dead, is purely coincidental.

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several points. Subjects were asked about their beliefs after reading about only one study, which either supported or opposed their view. W hether the study had a panel design or a co n cu rren t design, belief in initial position was strengthened if the study su p p o rted the su b ject’s initial position. But, again regardless of design, belief in initial position was affected relatively little if the study opposed the su b ject’s initial position. N either of these first two responses, it should be noted, is clearly counternorm ative. If one were to assum e that subjects already had good evidence supp o rtin g their beliefs (an assum ption the auth o rs regard as dubious), then their responses could be considered ap p ro p riate. It can be pro p er to criticize evidence that contradicts o n e ’s (well justified) belief m ore harshly than one criticizes evidence th at supports it, and consequently it can be pro p er to change belief m ore in response to su p p o rtin g evidence than in response to contradictory evidence. 3. T h e th ird result was an inevitable consequence of the reasoning that produced the previous results and this result was clearly co unternorm ative. A fter reading about both studies— one that supported th eir initial position and one that opposed their initial position (and with norm atively identical probative status on the average because of the co u nterbalancing of study design with study outco m e)— the subjects were m ore convinced of the correctness of their initial position th an they were before reading about any evidence. T h e w ork by L ord and colleagues suggests that people’s response to new evidence addressing a previous belief m ay som etim es be quite inap p ro p riate, (a) D ifferent stan d ard s are used for criticizing opposing evidence th an are used for criticizing supportive evidence, (b) Evidence generated by a m ethod th at does not m uch affect belief w hen it is opposed to the belief, strengthens belief substantially w hen it is supportive, (c) M ost im portantly, mixed evidence, which gives equal support to each of two opposing views, does not reduce confidence for holders of either view b u t instead reinforces confidence for holders of both views. T h e study is d istu rb in g on m any grounds, b u t we wish to highlight a particularly upsettin g im plication of the last finding. Before the advent of m odern social science, m any questions, like the issue of the d eterren t value of capital p u n ish m en t, were ones for which there really was no em pirical evidence one way or the o ther. It was nevertheless possible to appeal to logical or theoretical considerations in support of o n e ’s views, and it was possible to justify such views on epistem ic grounds. O ne m ight expect, though, that once genuine em pirical evidence for such questions becam e available, that evidence w ould sway opinion to w hichever side it supported or, if the evidence were m ixed, th at it w ould serve to m oderate opposing views. Instead, the effect of in tro d u cin g m ixed evidence m ay be to polarize public opinion, with pro p o n en ts of each side picking and choosing from the evidence so as to bolster their initial opinions. At any rate, this is the d reary possibility

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suggested both by B acon’s suppositions an d by the d ata of L ord and colleagues.

SEQUENTIAL PROCESSING OF EVIDENCE: TH E PRIMACY EFFECT

Well schooled children are told, alm ost as their earliest principle of social inference, that “ first im pressions are im p o rta n t.” T h e im plication is that one should take special care with o n e ’s self-presentation w hen m eeting som eone for the first tim e. T his rule is so widely tau g h t, an d co n trary principles so seldom find expression in the folk w isdom , that one would have to suspect that it expresses some fu n d am en tal tru th ab o u t social ju d g m e n t and im pression-form ation. In this case psychological research reinforces rath e r than questions the social-psychological lore. First im pressions are im p o rtan t, an d the prim acy effect in im pression form ation, in which early-presented in fo rm atio n has an undue influence on final ju d g m en t, is found alm ost as universally as w ould be suggested by its predom inance in lay psychological theorizing. T o be sure, recency effects, in which later-presented inform ation has u n d u e influence on final ju d g m en t, are som etim es found, b u t these are rare an d ap p ear to depend on the existence of one or m ore potently m anip u lated factors. T hese include (a) special m em orial constraints favoring the recall of later-p resen ted inform ation, (b) circum stances producing strong contrast effects, an d (c) p resen tatio n of inform ation about an object or process which can be presu m ed to be capable of changing over tim e, so that later in form ation, if it has im plications different from those of early inform ation, can be presum ed to be m ore valid (Jones & G oethals 1972). A lthough o rd er of presen tatio n of inform ation som etim es has no net effect on final ju d g m en t, and recency effects som etim es are found, these are the exception; several decades of psychological research have shown that prim acy effects are overw helm ingly m ore probable. W e would like to argue, following Jo n es and G oethals (1972), th at prim acy effects in inform ation processing are the rule because people are “ theorists” in their approach to inform ation ab o u t the social an d physical world. E arly-encountered inform ation serves as the raw m aterial for inferences about w hat the object is like. T hese inferences, o r theories ab o u t the nature of the object, in tu rn bias the in terp retatio n of later-en co u n tered inform ation. In line with the chief contention of this chapter, th en , theories about the nature of the object are revised insufficiently in response to discrepancies in the later-presented inform ation. W e will make no attem p t to review even partially the literatu re on o rd er effects in im pression form ation. Instead, we will briefly describe a few ex­

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em plary experim ents in ord er to highlight the issues central to o u r concerns. Solom on A sch, in his classic (1946) investigation, began a research tradition and a set of controversies which have continued until the present day. In the paradigm atic Asch experim ents, his subjects were presented w ith a series of adjectives allegedly describing a person and then were asked to evaluate the person. For exam ple, subjects were asked to evaluate a person who was: intelligent-industrious-im pulsive-critical-stubborn-envious. T his person was evaluated m ore positively than if the subject were exposed to the identical adjectives presented in the opposite order. T h e favorable im pression created by the early-presented adjectives in the First sequence, and the unfavorable im pression created by the early-presented adjectives in the second sequence tended to persist, with the consequence th at early-presented inform ation was m ore influential in the Final ju d g m e n t than later-presented inform ation was. A sch’s in terp retatio n of the results was essentially an extrem e version of the ‘‘early-hypothesis” arg u m en t outlined earlier. Asch held that early inform ation was processed ‘*holistically” and that the resulting G estalt colored the meaning of later-presented inform ation. In o u r exam ple, the early-presented inform ation that the target was intelligent, industrious, and im pulsive created not only a favorable im pression b u t a p articu lar kind of favorable im pression w hich actually altered the m ean in g of the later, less favorable adjectives so as to ren d er them affectively consistent with the early-form ed ‘‘G estalt’’ of a brig h t, energetic person, w ho, now , can be forgiven for his ‘‘critical” natu re (h ard to avoid if y o u ’re sm arter than your peers) and his “ stu b b o rn n ess’ (a consequence perhaps of b eing right because y o u ’re on your toes and do your hom ew ork). T h is left “ e n v io u s,” b u t let him who is w ithout sin . . . . In contrast, the opposite sequence also created a particu lar kind of unfavorable im pression. “ E n v io u s,” “ s tu b b o rn ,” and “ critical” created a recognizable persona of som eone who was hostile and pig headed. “ Im p u lsiv e” now m ade such a person doubly d an g ero u s, out of control. “ In d u strio u s” was also scary— all th at venom p u t to work. “ In tellig en t” ampliFied the th re a t— at least if he were stupid, y o u ’d have a chance. A sch’s contention that the w ords had a different m eaning w hen encountered in one o rd er than in the other has been challenged by a n u m b er of investigators, including O sgood, Suci, and T a n n e n b a u m (1957), B runer, S hapiro, and T a g iu ri (1958), an d , most notably and effectively, by A nderson (1965, 1971, 1974). T hese authors all argued that there is no direct evidence for any such change in m ean in g and that Final evaluations are easily predicted by a simple form ula w hich assum es constant weights for each of the adjectives modiFied only by the position o f the adjective in the list. Final evaluation is a function of the valence of the adjective taken by itself and the position of the adjective in the series . . . period. T h ere is no change in m ean in g because of the “ G e sta lt” created by preceding adjectives. T h e change-in -m ean in g hypothesis still has m any vociferous adherents,

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it should be noted, including R okeach and R o th m an (1965), W yer an d W atson (1969), H am ilton and Z an n a (1974), and H iggins an d R holes (1976) who hold a sim ilar, “ ch an g e-in -referen t” hypothesis, and the issue is far from resolved. F or ou r concerns, how ever, it does not m uch m a tte r w hether the changein-m eaning account o r the differential w eighting account is correct, as long as the prim acy effect can be in terp reted as o ccurring because early-form ed im pressions predom inate over the im plications of later inform ation. It seems that m ost parties to the debate agree on this in terp retatio n . T h e in terp reta tio n is central to the change-in‫־‬m ean in g view, b u t it is also im plicit in the view of A nderson and his colleagues, who ap p ear to prefer a “ d isco u n tin g ” explanation of the phenom enon. T h a t is, later-presented in fo rm atio n , if it is inconsistent with the affective im plications of early-presented inform ation, is “ disco u n ted ” or given a lower weight by the subject. T h e discounting ex p lan atio n can account for the prim acy effect only if one presum es th at it is the early inform ation that produces the im pression or belief against which the later inform ation is discounted. If the discounting of inconsistent in fo rm atio n were purely sym m etric tem porally, then there could be no prim acy effect. A nderson and others have suggested an o th er possible explanation for the prim acy effect, how ever, which assigns no role at all to processes of early theorizing and insufficient theory revision. T his is the possibility th at some prim acy effects m ay be caused solely by “ atten tio n d ec re m e n t” or sim ple failure to notice o r properly encode later-presented inform ation. F ortunately, a series of experim ents by Jo n es and his colleagues effectively ruled out this possibility as the sole explanation for prim acy effects. In the best know n of these experim ents (Jones, R ock, Shaver, G oethals, & W ard 1968), subjects were asked to w atch as a target person attem p ted to solve thirty m ultiple-choice analogy problem s. T h e problem s w ere described as being of equal difficulty. T h e target person always solved fifteen of the problem s. In one (descending) condition he solved d isproportionately m any problem s early in the series an d disproportionately few problem s late in the series, but in the o th er (ascending) condition the p attern was the reverse. Strong prim acy effects were observed such that early p erform ance received u n due w eight. If the target person solved m any problem s early in the series, subjects predicted that he would perform b etter on a second series o f sim ilar problem s, rated his intelligence as higher, and recalled that he had solved m ore problem s in the first series than they did if he solved few problem s early in the series. These results, especially the distorted recall results, w ould ap p ea r superficially to be readily explained as due to atten tio n decrem ent. Subjects, having “ got the p o in t” about the target person early in the series, m ight well have let their attention w an d er later in the series, h aving b etter things to do with their tim e than to pay close atten tio n to w hat m ust have been, after all, a rath er boring stim ulus situation. Jo n e s and colleagues, how ever, explicitly m a n ip u lated atten tio n by

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req u irin g subjects, in one set of conditions, to m ake probability ju d g m en ts of success before each trial. T h e ta rg e t’s success or failure then served as imm ediate feedback on the accuracy of the subjects’ predictions. Subjects, as it happens, tracked changes in objective probability quite well an d thus were highly responsive to the feedback. T his m anip u latio n of atten tio n , contrary to w hat w ould be expected on the basis of the atten tio n decrem ent hypothesis, did not reduce prim acy effects. O n the co ntrary, the attention m an ipulation resulted in a slight increase in prim acy effects. O th er experim ents by Jo n e s and his colleagues shed fu rth er d o ubt on the view that prim acy effects are wholly or even partially due to atten tio n decrem ent. T h ey supported instead the view advocated by Jo n es and G oethals and the present w riters that prim acy effects are due to theories that are form ed early and w hich are insufficiently sensitive to the im plications of subsequent data. T h e m echanism s of p rem a tu re com m itm ent and insufficient revision are probably aided an d ab etted in m ost real life contexts by people’s adherence to w hat we have called the dispositionalist m etatheory. T his m etatheory produces w hat H eid er called “ the false idea of the invariance of the behavior of the other p erso n ” (1958, p. 55). If we regard people’s behavior as in v arian t, then this gives license to the m echanism s u n d erlying the prim acy effect. (1) T heoretical com m itm en t at an early stage is justified because the in d iv id u al’s characteristics are in v arian t an d a small am o u n t of inform ation is quite sufficient to allow one to know w hat a p erso n ’s dispositions are. (2) T h eo ry revision is rarely necessary because, again, characteristics are in v arian t, and later inform ation seldom will be truly inconsistent with earlier inform ation.

BELIEF PERSEVERANCE AFTER E V ID E N T IA L D ISC R ED IT IN G

T h e third class of perseverance ph en o m en a is the in d iv id u al’s response, not to new evidence, b u t rath e r to challenges of the evidence that initially led to the belief’s form ulation. At an anecdotal level it is easy to cite circum stances in which such challenges occur. Ja c k believes that he dislikes abalone because of his first an d only exposure to that food and then is assured by an abalone connoisseur that he sam pled an inferior frozen product p rep ared in a notoriously dreadful restau ra n t. J a n e is h earten ed by a correspondence school’s enthusiastic appraisal of her potential as a com m ercial artist and then finds th at three of her peers who answ ered the sam e advertisem ent received equally glow ing assessm ents. A scientist is told by a colleague ab o u t an experim en t show ing some su rprisin g effect and then is later told by the sheepish colleague that the experim ent was only a “ th o u g h t-ex p erim en t” described in a p o p u lar psychology m agazine.

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N orm atively, it is clear w hat the effects of such evidential discrediting should be. J a c k ’s belief ab o u t his dislike for abalone, J a n e ’s belief ab o u t her artistic potential, and the scientist’s belief about the su rp risin g p h en o m en o n ought to retu rn to som ething close to their ‘‘p reev id en tial” levels. T he perseverance hypothesis, as developed by R oss an d L ep p er and their colleagues, suggests that people such as those described would persist in their initial assessm ents to an u n w arran ted degree. T h is hypothesis presupposes that we can determ ine w hen the person is “ in a p p ro p riate ly ” persisting in an im pression or belief whose basis has been u n d erm in ed . T h o u g h it can often be difficult to m ake such a d eterm in atio n , it is not im possible in principie. T o explore the perseverance hypothesis experim entally, a p arad ig m is requ ired which perm its us to specify precisely how m uch perseverance and how m uch change m ight be “ w a rra n te d ” by some acceptable norm ative stan d ard . O ne response to this strategic dilem m a has been the ad o ption of the total discrediting or “ d eb riefin g ” p arad ig m . T h ere is one challenge to the evidence underlying an initial im pression th at does suggest a decisive test of the perseverance hypothesis, and it occurs w hen a person discovers th at the entire evidence base for the initial ju d g m e n t is not m erely biased or tain ted b u t is com pletely w ithout value. T h is situation should be fam iliar to all social psychologists who have ever used deception in their research, for postdeception “ debriefin g ” procedures are designed to discredit totally the previous deceptive inform ation and thereby to elim inate any effects th at such inform ation originally m ay have had on the subjects’ feelings or beliefs. It is notew orthy that inform al accounts of the difficulty of debriefing are com m on. W hile the vast m ajority of deception studies involve m an ip u latio n s of relatively innocuous im pressions, m any professionals nevertheless have expressed concern that experim ental deceptions m ay som etim es do h arm that conventional debriefing procedures fail to com pletely undo (K elm an 1972; M iller 1972; O rn e 1972; Silverm an 1965). L ater in this ch ap ter we will re tu rn to both the practical problem of im proving debriefing procedures and to the far m ore general issue of overcom ing discredited personal an d social im pressions. For now, let us m erely observe that it was partially this professional concern (along with a provocative hint from an earlier study by W alster, Berscheid, A braham s, & A ronson 1967) that led Ross and L ep p er and their colleagues to adopt the “ d eb riefin g ” parad ig m to explore the theoretical problem of belief perseverance. In the first such study (R oss, L epper, & H u b b a rd 1975), subjects were recruited for a study allegedly concerned with the effects of problem -solving feedback on various physiological responses. Subjects were p resented with a novel task, distinguishing betw een au thentic suicide notes and u n au th en tic ones. As the subjects w orked, they were provided w ith false feedback after each trial, which indicated th at, overall, they had perfo rm ed at close to an average level, at a level m uch above average (success condition), or at a level

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m uch below average (failure condition). Following this outcom e m anipulation, subjects were thoroughly debriefed concerning the p redeterm ined and ran d o m n a tu re of th eir task outcom e. T h ey not only were told that their feedback had been false b u t also were shown the ex p erim en ter’s instruction sheet assigning them to the success, failure, or average perform ance condition and specifying the feedback to be presented. S ubsequent to this debriefing, subjects w ere asked to fill out a postexperim ental q u estio n n aire (ostensibly to help the ex p erim en ter in terp ret their physiological records) on which they w ere required to estim ate their actual perform ance at the task, to predict their probable success on related future tasks, and to rate their ability both at the suicide discrim in atio n task and at o ther related tasks involving social sensitivity. T h e results revealed a rem arkable degree of postdebriefing perseverance. Even after debriefing, subjects who had initially been assigned to the “ suecess” condition co n tinued to rate th eir perform ance and abilities far m ore favorably than did subjects whose initial feedback had indicated average perform ance, while subjects initially assigned to the failure condition showed the opposite p attern of results, co n tin u in g to rate them selves as unsuccessful and lacking ability for the experim ental task and for other, sim ilar ones. T o replicate this perseverance p henom enon and extend it from the dom ain of self perception to th at of social perception, a second experim ent was u n d erta k en . T h is tim e, actor subjects distinguished real from fictitious suicide notes while yoked observer subjects (from behind a one-w ay m irror) w itnessed the initial false feedback presentations and the later debriefing given by the ex p erim en ter. Several additional experim ental conditions were incorporated into the experim ental design of this follow-up study. First, “ nod eb riefin g ” conditions were included to assess the initial im pact of the false feedback. Second, a set of “ process” debriefing conditions was included in which actors, overseen by observers, received not only the inform ation about the random assignm ent and false feedback presented in the stan d ard “ outco m e” debriefing conditions b u t also an extensive discussion of the perseverance p h en o m en o n , the processes that m ight co n trib u te to it, and the potential personal relevance and costs of erroneous im pression perseverance. T h e results, presented in F igure 8 .1, revealed that there was substantial perseverance o f the initial im pressions for both actors and observers after stan d ard “ o u tc o m e” debriefing procedures. A pproxim ately half of the predebriefing difference in self-perceptions and social perceptions rem ained despite the thorough discrediting of the basis for these initial im pressions. M ost of these differences w ere successfully elim inated w hen actors were exposed to the considerably m ore pointed and extended “ process” debriefing. For observer subjects, the perseverance effect seem ed even stronger. Even after process debriefing, the observers continued to view the ac to r’s ability as consistent w ith the a c to r’s discredited initial experience of success o r failure.

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GO LÜ

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Fig. 8.1 Post-debriefing differences between success and failure groups in beliefs about performance and ability, for actors and for observers. From Ross, Lepper, & Hubbard 1975. T h e data from the process debriefing conditions are im p o rtan t from a practical and ethical standpoint as well as from a theoretical one. A ctors, who had personally received the pointed description of m echanism s th at m ight lead their erroneous self perception to persevere, showed very little residual effect of the discredited outcom e m anipulations. O bservers, who m erely had witnessed the acto rs’ process debriefing, continued to show considerable perseverance in their beliefs about those actors. It seems probable th at a process debriefing directed specifically at the social perceptions of the observers m ight have been m ore effective, although this rem ains to be d em o n strated em pirically. In any case, the advisability of b uttressing debriefing procedures w ith a discussion of possible perseverance m echanism s seems clear. Equally clear is the researchers’ ethical responsibility to evaluate, ra th e r th an m erely assum e, the sufficiency of any debriefing procedures, at least in those studies where the m anipulated im pressions are relevant to self esteem or to perceptions or attitudes of social consequence. D em onstrations of postdebriefing perseverance now have been extended to a variety of im pressions and beliefs (for exam ple, A nderson, R oss & Lepper 1979; Jen n in g s, L epper an d Ross 1979; Ross & A nderson 1979). T w o ex‫״‬ perim ents were conducted outside the laboratory setting (L ep p er, Ross & Lau 1979). H igh-school students were led to form erroneous im pressions of their abilities to solve “ logical-reasoning” problem s. H alf the subjects received a clear, coherent lecture th at prom oted subsequent success by illustrating the use of a simple m atrix to solve one of the seem ingly difficult and 178

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com plex puzzles. T h e rem ain in g subjects, by contrast, w itnessed the solution of the sam e puzzle accom panied by a ram b lin g an d unhelpful series of exhortations. T h e subjects then attem p ted to solve a series of puzzles on their own. As plan n ed , 44tu to re d ” subjects perform ed extrem ely well on the task, while 44p laceb o -treated ” subjects perform ed poorly. Follow ing the instructional sessions an d tests, half the subjects in each condition w ere fully 44d eb riefed ” on the likely cause of their test perform ance. T h e ex p erim en ter explained in detail the superior or inferior n atu re of the instruction they had received. (In fact, in one of the studies, subjects actually were allowed to view the sam e videotaped lecture that had been shown to subjects in the opposite co n d itio n .) 44D eb riefed ” subjects also were allowed to solve a new problem using the subsequently revealed technique. T h e other half of the subjects were given no such debriefing experience. All participants then rated th eir abilities for the task, th e ir liking for the task, and th eir probable future perform ance both at the experim ental task and at o ther related tasks. A delayed posttest, dissociated from the experim ental setting, also was given. S tudents w ere asked, in th eir regular classroom s, to respond to a survey allegedly conducted by the school’s m athem atics d ep artm en t which solicited stu d en t reactions to various potential additions to the d e p a rtm e n t’s cu rricu lu m , including one which involved problem -solving tasks of the sort subjects had w orked on d u rin g the experim ental session several weeks before. A lthough 44d eb riefed ” subjects were aw are of the differential effectiveness of the two teaching procedures (th at is, they accurately predicted the extent of perform ance difficulties for peers exposed to the two procedures), they continued to ju d g e th eir own ability according to their initial experience of success or failure. P articu larly d ram atic were the results of the delayed follow-up m easures which indicated th at 44d eb riefed ” subjects’ self-appraisals and task preferences co ntinued to be quite influenced by their original success o r failure. In fact, the debriefed subjects were virtually indistinguishable on m ost of these m easures from the subjects who were never debriefed.

M EC H A N ISM S U N D ER LY IN G PERSEVERANCE PH ENOM ENA

T h e evidence suggests th at Bacon was correct in his assertion that 44the h u m a n u n d erstan d in g w hen it has once adopted an opinion draw s all things to support and agree with it” (1620/1960, p. 50). C onflicting evidence is treated as if it were supportive of beliefs, im pressions form ed on the basis of early evidence survive exposure to inconsistent evidence presented later, and beliefs survive the total discrediting of their evidence base. W hy do people persevere in ad h erin g to beliefs an d theories? O r, to ask a m ore easily answ ered questio n , how do they persevere? O n e obvious answ er is th a t they persevere because they w ant to. M an y

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beliefs are cherished because they em body strongly held values. W hen such beliefs are challenged, people then p u t into operatio n w hatever cognitive m achinery will suffice to discredit uncongenial evidence and to bolster supportive evidence. T h o u g h such an answ er is not a sufficient ex p lanation, because it does not specify precisely w hat the relevant cognitive m ach in ery m ight be, it is a satisfactory “ first-cause” explanation for m an y belief perseverance phenom ena. T o the extent that a person is em otionally comm itted to a given belief, it certainly seems likely th at th at person w ould cling to that belief by w hatever cognitive tricks are necessary. Such a m otive surely is present in the reactions of religious fundam entalists to historical evidence o f Biblical m atters, in the reactions o f scientists to research discrediting their life work, and perhaps even to the reactions o f subjects in som e of the experim ents we have discussed. It seems entirely likely, for exam ple, that the extrem e counternorm ative reaction to new evidence by subjects in the experim ent by L ord and colleagues (1979) was at least partially because of the relative im portance and value centrality of beliefs about capital p u n ish m en t. It is doubtful that such extrem e reactions w ould have been elicited to evidence concerning subjects’ beliefs about the advisability o f an an n u al chest X -ray or about the financial advantages of the C o m m o n M ark et to its p articip an ts. E m otional com m itm ent, how ever, seems to us to be generally n eith er a necessary nor a sufficient explanation of belief perseverance p h en o m en a. Em otional com m itm ent is scarcely likely to be an im p o rtan t com p o n en t of subjects’ initial im pressions of a target person described by A sch ’s adjective strings or to initial im pressions of the problem -solving ability of a targ et person in the experim ents by Jo n es and others (1968), or, still less, to the discredited belief of a subject in the L epper, Ross, and L au (1978) ex p erim en t that he has little ability to solve m athem atical puzzles. T h e notion of em otional com m itm ent also tells us noth in g about the precise cognitive m eans by which com m itm ent could serve the goal of belief perseverance. W e prefer several other, m ore purely inform ation-processing explanations for perseverance p h en o m en a, while acknow ledging that these often m ay be triggered or strengthened by purely m otivational considerations. (See K atz 1960.) W e already have discussed some of these cognitive m echanism s. W e now add three m ore, the first two of w hich are particu larly ap p ro p riate to un d erstan d in g belief perseverance following total discrediting o f the evidence base, and the last o f which seems to au gm ent all three types o f belief perseverance phenom ena we have discussed.

Biased R ecollection and Interpretation o f E vidence

W hy is it that J a n e , a subject in the R oss, L epper and H u b b a rd (1975) experim ent, who learns that her excellent ‘‘p erfo rm a n ce” on the suicide note discrim ination was determ in ed by a ran d o m n u m b er table, clings to the

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hypothesis that she is actually ra th e r talented at such discrim inations? Even m ore perplexing, upon learn in g that h er abysmal ‘‘perfo rm an ce’’ was random ly d eterm in ed , why does J a n e not breathe a sigh of relief an d revert to her initial opinion of this ability and related ones involving social sensitivity? It seems to us th at these questions are puzzling only if one assum es that the only m ental events tran sp irin g in J a n e ’s head as she pursues the task are bland and passive registrations of the feedback given by the experim enter. T h a t assum ption is unjustified, and it seems m uch m ore likely that the impression of h er ability that is created by the feedback prom pts a search for additional inform ation p ertin en t to the im pression. Suppose J a n e receives feedback suggesting that she is uncannily suecessful at the task. It seems likely th at she will have no trouble generating additional “ evidence” that seems consistent w ith h er ap p aren t social sensitivity. H e r reasonably good perform ance in h er abnorm al psychology course, her ability to m ake new friends easily, and h er increasing sense of confidence and assurance as she progressed in the suicide note task, all m ight be seen as “ further evidence” of such pow ers. Suppose, on the other hand, that J a n e receives feedback suggesting th at she is particularly poor at the task. A gain, supporting “ evid en ce” probably can be generated with ease. J a n e m ight note her difficulty in im ag in in g herself as lonesom e or alienated, her m ediocre perform ance in her social problem s course, and h er increasing sense of confusion and hesitation as she progressed in the suicide note task. Needless to say, even an objectively neu tral set o f evidence, if processed in accord with such a “ confirm ation b ia s ,” could bolster the im plications of either the success or the failure outcom e. W e have no direct evidence that subjects in the experim ent by Ross and colleagues (1975) engaged in such confirm ation-biased processing of evidence stored in m em ory. But there is a rich research literatu re that shows the operation of a variety o f encoding and decoding biases that favor confirm ation of p rio r hypotheses or beliefs over disconfirm ation. T h ere is good evidence, for instance, that people tend to recognize the relevance of confirm ing cases m ore readily than th at of disconfirm ing ones, and therefore tend to search for such cases in evaluating th eir hypotheses (W ason and Jo h n so n -L aird 1965). As philosophers o f science (P o p p er 1959) have long m ain tain ed , this strategy is not m erely inefficient, it is b o u n d to make even the m ost dubious of hypotheses ap p ear to enjoy em pirical support. S nyder and Sw ann (1978) exam ined confirm ation tendencies in the dom ain o f social inference. W hen subjects were asked to determ ine in an interview w ith an o th er, “ ta rg e t” subject, w hether or not the target was an “ extro v e rt,” they tended to ask prim arily those questions to which a positive answ er w ould have provided “ ev id en ce” for the ta rg e t’s extroversion, b u t a negative answ er w ould have provided, at m ost, weak evidence that the person was not an extrovert. W hen asked to d eterm ine w hether the target was an “ in tro v e rt,” subjects used the com plem entary strategy of asking prim arily

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those questions to which the answ er, if positive, w ould have provided “ evidence” for the ta rg e ts introversion b u t, if negative, w ould have provided only weak evidence th at the person was not an intro v ert. Such strategies would tend to establish that alm ost anyone is an extrovert if one starts with an “ extrovert hypothesis, ” and to establish that alm ost anyone is an in tro v ert if one starts with an “ introvert h y p o th esis.” A nd, in fact, in one of S n y d e r’s and S w ann’s experim ents, observers listened to the targ et subjects’ answ ers to the interview er subjects’ probes an d concluded th at the target was an extrovert if the interview er was testing the “ extrovert hyp o th esis” an d coneluded that the target was an in tro v ert if the interview er was testing the “ introvert hypothesis.” W e should em phasize that it is not always the case th at confirm ing instances are m ore available to the theory holder than disconfirm ing ones. As H astie and K u m a r (1979) noted, surprising or inco n g ru en t events m ay be attended to and even stored in m em ory m ore th an expected or “ hypothesisconfirm ing” events. T h e literatu re is n o t uniform on this point, how ever, and there is also evidence that con g ru en t inform ation is som etim es stored m ore readily than incongruent inform ation. T h e literatu re is q uite consistent, how ever, in showing the advantage that confirm ations enjoy over disconfirm ations in the retrieval or o u tp u t stage. A study by Snyder an d C a n to r (1979), closely paralleling the S n y d er an d Sw ann study, shows that m em ory searches favor hypothesis-confirm ing evidence even w hen the hypothesis is m erely a tentative one. Subjects read a lengthy story ab o u t a young w om an who behaved in a n u m b e r of ways that could be characterized either as “ ex tro v e rted ” or as “ in tro v e rte d .” T w o days later, some of the subjects were asked to assess the w o m an ’s suitability for an “ ex tro v erted ” occupation, nam ely, real estate sales, and o th er subjects were asked to assess the w o m an ’s suitability for an “ in tro v erted ” occupation, nam ely, research lib rarian . T h e subjects had to consult their m em ories for evidence pertinen t to the “ hypothesis” of extroversion o r introversion. T h e results showed th at there was a strong confirm ation bias in the retrieval process. Subjects testing an extrovert hypothesis recalled m ore ex tro v ert item s than did controls or subjects testing an in tro v ert hypothesis, while the subjects testing an introvert hypothesis recalled m ore intro v ert items th an did controls or subjects testing an extrovert hypothesis. P eople’s hypothesis-testing strategies are rem iniscent of th eir tendency to utilize only conceptually positive inform ation in concept fo rm ation tasks (chapter 3) and rem iniscent also of their tendency to pay atten tio n p rim arily to the present/p resen t cell o f 2 x 2 contingency tables (ch ap ter 5). All such strategies indicate people’s failure to appreciate intuitively the great pow er of the scientific strategy of disconfirm ation or hypothesis invalidation. If they are ignorant of this strategy, this w ould help to explain why subjects in the studies by Ross, L epper, an d their colleagues are left so m uch at the m ercy of hypotheses suggested to them by the false “ d a ta ” they en co u n ter, even w hen those hypotheses are uncongenial and un flatterin g . T h e tendency to search

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for additional, confirm atory evidence usually will be 4‘re w a rd e d .” T h e person is then left w ith this additional “ ev id en ce” even after the false n atu re of the experim ental feedback is revealed. T en d en cy to Search for Causal E xplanations

It seems likely th a t subjects in the experim ents by R oss, L epper, and their colleagues w ould not have restricted th eir “ ex tra cu rricu lar” m ental activity to a search for confirm atory evidence. Like the professional scientist, the lay scientist tends to look for causal explanations of observed data. Retu rn in g to J a n e , o u r hypothetical subject in the Ross, L epper, and H u b b ard (1975) ex p erim en t, suppose th at she has received feedback indicating that she is quite good at distinguishing betw een au th en tic and false suicide notes. W ould she experience m uch difficulty in explaining why she m ight have this p articu la r talent? It seems likely th a t she w ould n o t and th a t the same storehouse that provided h er w ith additional “ evidence” of h er ability also could provide her w ith satisfactory “ causal ex p lan atio n s.” H e r fam iliarity with the w ritings of a fam ous novelist who recently com m itted suicide, her part-tim e jo b as a p aram ed ical assistant, and h er generally “ o p e n ” relationship w ith her parents and friends all m ight serve to explain h er high level of ability at a task req u irin g social sensitivity. O n the o ther h an d , suppose J a n e receives feedback indicating that she is poor at the task. A gain, h er storehouse of personal inform atio n can probably be counted upon to suggest causal explanations. H e r lack of personal acq u ain tan ce w ith anyone w ho is seriously depressed (let alone suicidal), even her lack of secondhand fam iliarity with such people (save th ro u g h the w ritings of one au th o r who recently com m itted suicide), m ight help to account for her relative lack of ability to distinguish betw een au th en tic and fake suicide notes. T hese speculations ab o u t J a n e ’s introspections would be plausible if it could be presum ed th at (a) subjects are indeed inclined to generate causal explanations for events such as successful or unsuccessful perform ance at the suicide note discrim ination task, (b) people generate such explanations with relative ease, and (c) once such explanations are generated, they are reasonably convincing. T h e re is both direct an d indirect evidence for each of these suppositions. M uch research on causal attrib u tio n shows th at people readily generate causal explanations of events w hen they are asked to do so by an exp erim en ter. Investigators who approach subjects with causal analysis protocols, p ro b in g them for explanations of events, are seldom disappointed in th eir yield. W hen asked, people are rem arkably facile at inventing explanations w hich they ap p ear to find plausible and presentable even to outsiders as prestigious as scientific investigators. T h is generalization has been shown to hold even u n d e r circum stances in which it can be shown that such causal explanations have no em pirical fo u ndation (N isbett & W ilson 1977b; W ilson & N isbett 1978).

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T his sort of research does not suffice to show that people spontaneously engage in m uch causal explanation in the absence of p ro m p tin g by an attrib u tion researcher. U npublished work by N isbett, H arv ey , and J . W ilson (1979), how ever, suggested that such spontaneous causal analysis m ay be rem arkably com m on. These investigators ‘‘b u g g ed ’’ a total of th irteen haphazardly selected conversations ran gin g from g rad u ate stu d en t bull sessions, to singles b ar conversations, to a picnic for lower socioeconom ic status senior citizens. T h e “ epistem ic” category of each statem ent u tte re d , and each of the requests eliciting a statem ent, were coded. C ategories included “ gives in fo rm atio n ,” “ gives e v alu atio n ,” “ gives advice or su g g estio n ,” “ m akes p red ic tio n ,” and “ gives causal an aly sis.” S tatem ents expressing or requesting causal analysis were rem arkably frequent, accounting for 15 percent, on the average, of all utterances. Even for the conversation in w hich causal analysis was the least frequent (the senior citizens’ picnic), causal analysis accounted for 5 percent of all utterances. T hus, people engage in causal analysis frequently, an d they do it w ith facility both in the laboratory and in their everyday lives (judging from the rarity w ith which conversationalists in N isb ett’s an d colleagues’ study appeared stum ped by one a n o th e r’s requests for causal explanations). D o they find such explanations convincing, once generated? A series of experim ents by Ross, L epper, and their colleagues suggested that they do and that once people have generated causal explanations for events and relationships between events, they find those events and relationships to be plausible even when the evidence for them is show n, th ro u g h the debriefing p arad ig m , to be nonexistent. In the first of these studies, by Ross, L epper, Strack, an d S teinm etz (1977), subjects were asked to place them selves in the position of a clinical psychologist attem pting to u n d erstan d and predict a p a tie n t’s behavior on the basis of background inform ation. T o this end, they were given an au th en tic clinical case history which detailed the early experiences in the life of either an u n h appy and som ew hat neurotic young w om an or a chronically u n em ployed and depressed m iddle-aged bachelor. In various experim ental conditions subjects were asked to use this case history to explain some “ critical e v e n t” in the p a tie n t’s later life (for exam ple, a suicide, a h it-an d -ru n accident, jo in in g the Peace C orps, a candidacy for public office). C ontrol subjects w ere not asked to explain any such events. Following the explanation task, the experim ental subjects were carefully inform ed that the events they h ad been asked to explain were purely hypothetical and th at, in fact, there was no available inform ation about the later life of the patient whose history they h ad read. T h en each subject was asked to assess the likelihood of a n u m b e r of possible events in the p a tie n t’s later life, including the critical events that h ad been explained in the various experim ental conditions. As expected, the subjects’ likelihood estim ates revealed a m arked effect of the explanation task. H av in g initially

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explained an event, subjects rated the event as m ore probable after ‘‘debriefin g ” th an did subjects who had not explained that event or th an did subjects who had explained an alternative event. T h e process of causal explanation influences plausibility or subjective likelihood even w hen there is no previous induction of belief in the event. Ross and colleagues (1977) found that subjects who engaged in purely “ h y p o th etical” ex p lan atio n — explaining events that they knew from the outset to have been arbitrarily chosen and not to have been based on any know ledge about p a tie n ts’ later lives— sim ilarly showed a strong tendency to rate the explained event as relatively likely. A n analysis of the actual explanations w ritten by subjects was instruetive. T h e facility w ith which subjects could pass from alm ost any real event in the past history of the client to alm ost any hypothetical event was positively alarm ing. For exam ple, one p a tie n t’s youthful decision to jo in the N avy was cited as very significant both by subjects asked to explain a subsequent candidacy for political office and by subjects asked to explain a subsequent suicide! In the form er case, how ever, service in the N avy was seen as symptom atic of the “ greg ario u sn ess” and the “ desire to serve” that m ight characterize a potential politician, while in the latter case it was seen as a sym ptom of the p a tie n t’s predisposition to “ punish others by ru n n in g a w ay ,” thus foreshadow ing his suicide.2 In an o th er study, A nderson, R oss, and L epper (1979) explored the role of causal explanations in reinforcing and m ain tain in g m ore abstract and general theories. In one key condition of the study, subjects were first led, on the basis of only two concrete cases, to hypothesize a positive or negative relationship betw een a p articu lar occupational outcom e (success versus failure as a firefighter) and a prognostic variable (risk preference on a p ap er‫־‬an d ‫־‬pencil test that the firefighters had taken as trainees). T h ey then were asked to w rite an explanation of th at relationship, only to learn later that the relevant d ata were totally fictitious and that o ther participants had been exposed to an opposite p attern of results. T h e degree of belief perseverance am ong these subjects was substantial. In fact, subjects’ belief in w hichever relationship they had been encouraged to explain was alm ost as great as for those subjects who had seen the “ d a ta ” b u t neither had explained it nor had been told that it was fictitious! Interview s w ith subjects who had explained the “ d a ta ” and then had been debriefed were unsettling. T ypically, such subjects justified their views by insisting th at, despite the discrediting of the data, it was obvious that the p articu lar relationship they had explained was the correct one. Indeed, several expressed surprise that subjects in the other condition had been gullible enough to form the opposite hypothesis. T h e evidence suggests th at a little causal analysis is a dangerous thing. 2 Any resemblance between the behavior of subjects in this experiment and that of any clinician, living or dead, is purely coincidental.

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P eople’s facility in form ing causal explanations is so great that they usually will be able to explain m ost events and relationships they observe. T h ese explanations m ay often prove so convincing that they survive even the total discrediting of the 4‘evidence” th at p ro m p ted their invention in the first place. It is w orth focusing on the norm ative problem here, because it is subtle. T h ere is nothing w rong w ith co n tin u in g to believe in the plausibility o f events and relationships when one has a pow erful causal m odel w hich ineluctably dictates their existence. C onsider a student who is told of experim ents showing that light rays are deflected w hen they pass th ro u g h the g ravitational field of the sun and then recognizes, because of his accurate u n d erstan d in g of relativity theory, that such a result is dem an d ed by the theory. Such a stu d en t would be justified in m ain tain in g his belief in the hypothesis that light rays bend w hen passing through the s u n ’s g ravitational field, even if he w ere subsequently told on the best auth o rity that the experim ents he h ad h eard about were totally valueless artifacts. It seems to us th at the difference between this hypothetical student and the subjects in the experim ents by R oss, L epper, and their colleagues is ju s t as great as the difference betw een a causal theory as pow erful and w ell-supported as relativity theory and the flimsy, ad hoc “ causal theories” invented by the subjects. It is the m isplaced confidence in their facile causal theories which trips u p the subjects in these ex p erim en ts, not their willingness to speculate ab o u t them at the request of the experim enter.

B ehavioral C onfirm ation Biases: T he S elf-fulfilling Prophecy

T h e experim ents by Ross, L epper, and their colleagues cap tu re m an y of the elem ents of everyday-life situations in which beliefs are seen to persevere beyond the point at w hich the evidence can sustain them . T h ey lack, how ever, an elem ent that is often present in everyday life, nam ely, the ability to intervene and test hypotheses by generatin g new d ata. Such in terv en tio n provides great o p portunities, b u t it also carries co m m en su rate risks. If hypotheses are tested effectively, for exam ple, if disconfirm atory d ata are sought as eagerly as confirm atory d ata are, then belief perseverance can be avoided. If, on the other h an d , prim arily or exclusively co n firm ato ry d ata are sought, or worse, if such confirm atory d ata are m an u factu red , m erely because the person holds a certain hypothesis, then perseverance o f incorrect beliefs is m ade doubly likely. It is not h ard to think of anecdotal evidence suggesting th at biased d ata generation m ay be as com m on as biased d ata retrieval. C o n sid er Jill, a fourteen year old who is positive th at she cannot do m athem atics (perhaps because

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she has been assured th at “ girls are ju st no good at that kind of th in g ” ). She is likely to select academ ic courses an d activities th at prom ise to spare h er from frustration an d seem ingly certain failure. In so doing, she fulfills her negative self-appraisal by the tim e she enters college. O r consider Ja c k , the w ould-be suitor who “ know s” that he is doom ed to be rejected. H e is not likely to behave in a m a n n er th at perm its his hypothesis to be o v ertu rn ed by experience. Ind eed , if he does sum m on the courage to approach the object of his affections, his appeal is apt to be so strain ed , so tentative, an d so defensive that rejection becom es highly probable. Such stories need not have u n h ap p y endings. For instance, consider a person w ho is convinced th at a p articu lar location is “ ju st right for a small grocery sto re” an d invests his life savings to back the “ th e o ry .” Such an ,individual is apt to exploit his ow n tim e an d energies mercilessly an d thereby succeed in “ p ro v in g ” that his gam ble an d the beliefs th at p ro m p ted it were well advised. O r consider the com pany th at com m its its resources to developing m otor X ra th e r th an m o to r Y on the basis of a feasibility study an d then succeeds in proving its choice was correct by overcom ing all of the engineering obstacles necessary to produce m otor X. Like o u r anecdotes, the literatu re on self-fulfilling prophecies shows that people often do proceed in such a m a n n er as to alter reality in the direction suggested by the initial hypothesis. T h e fam ous (b u t controversial) “ P y g m alio n ” studies by R osenthal an d Jaco b so n (1968) are a case in point. T hose investigators random ly selected certain elem entary school pupils and inform ed th eir teachers th at psychological tests had shown th at the pupils w ere due for a learn in g sprint an d rap id advance in intellectual ability that year. T h e teachers ap p aren tly behaved tow ard the children in ju st such a way as to elicit intellectual grow th in these children, since they did gain m ore in objectively m easured intellectual ability d u rin g the subsequent y ear than their peers did. P articularly persuasive evidence o f p eople’s tendency to elicit behavior from óthers according to th eir initial hypotheses has been collected by S nyder an d his colleagues. W e have already m entioned the study by Snyder and Sw ann (1978), in which it was shown that subjects who were interview ing som eone to d eterm in e w hether or not the person was an extrovert tended to ask questions w hich p rim arily elicited “ d a ta ” indicating th at the person was indeed an extrovert. In an even m ore provocative experim ent, Snyder, T a n k e , an d Berscheid (1977) showed th at “ hypotheses” m ay guide b ehavior tow ard the targ et in such a way as to be self-confirm ing even w hen the situation is less form al an d the person is not given the som ew hat artificial task of “ te stin g ” the hypothesis. M ale subjects were asked to engage in a conversation via intercom w ith an u nseen female p a rtn e r w hom they believed to be eith er unusually attractive or u n attractiv e in appearance. T h e female su b ject’s side of the conversation was recorded and then played for a second

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m ale subject who subsequently estim ated h er attractiveness. T h e second m a le’s beliefs agreed with the hypotheses of the first m ale subject. T h e first m ale subject ap p aren tly had elicited verbal b ehavior from the fem ale th at provided the second m ale with “ evidence” of h er probable attractiveness. W ork by Kelley and Stahelski (1970) suggests that not m erely specific beliefs about particu lar individuals, b u t also m uch m ore general theories an d even w hat m ight be called w orld views, m ay receive “ su p p o rt” from the behavior o f others in response to o n e ’s own th eory-guided behavior. K elley and Stahelski presented subjects w ith a stan d ard p riso n e r’s dilem m a gam e and explained the payoffs associated with various m oves an d counterm oves. T hey then asked subjects to describe th eir u n d erstan d in g of the gam e and the appropriate strategy. Some subjects spontaneously expressed the view th at the point of the gam e was to encourage the oth er player to adopt a cooperative strategy, so as to m axim ize the likelihood th at the outcom e w ould be a slow, steady payoff for both players. O th e r subjects thought th at the p o in t o f the gam e was to compete with the o ther player. T hese subjects said th at the appropriate strategy was to lure the o ther player into m aking the “ co o p erativ e” m ove as often as possible and then to m ake the “ co m p etitiv e” m ove so as to get the high payoff for them selves th at w ould result from this p attern (an d , incidentally, resulting in a large loss on th at m ove for the o th er player). T h e experience o f the cooperative players, w hen they actually cam e to play the gam e, was quite variable. If they were p aired w ith a “ c o o p e ra to r,” they quickly settled into a m utually cooperative p attern . If they w ere paired w ith a “ co m p etito r,” they w ere forced into a com petitive strategy in o rd er to avoid consistent, large losses. T h e experience of com petitors, on the o th er hand, was uniform . If paired with an o th er com petitor, they settled quickly into the consistently com petitive and ultim ately m utually self-defeating strategy. If paired with a cooperator, th eir own b eh av io r sooner or later forced the cooperator into a defensive com petitive strategy also. T he intrig u in g point o f the Kelley and Stahelski d em o n stratio n is that cooperators will learn, correctly, th at the w orld contains both cooperators and com petitors. C om petitors, on the o th er h an d , will learn, incorrectly, th at everyone out there is a com petitor. T h is is because co m p etito rs’ own view of correct strategy will bias the b ehavior of others so as to produce evidence indicating that everyone shares th eir own strategy.

W HEN THEORIES AND BELIEFS DO CHANGE

W e have been able to present a substantial am o u n t of evidence show ing that beliefs tend to persist u n d er circum stances in w hich they have ceased to be an accurate ch aracterization of the w orld, an d we also have been able to

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provide some evidence on the m echanism s th at foster belief perseverance. But have we com m itted the sam e erro r that o u r subjects did? H ave we selected and generated evidence in such a way as to confirm our own hypothesis of belief perseverance? W e believe not. W e can find no literature showing that people pu rsu e, even in lim ited dom ains, hypothesis-testing strategies that w ould facilitate the rejection of inaccurate beliefs. T h e experim ents we reported were constructed in such a w ay that they could have shown evidence for belief perseverance, for its opposite, or for som ething in betw een. W e welcome investigations th at are guided by the opposite of the hypothesis that produced m ost of the research we have discussed. W e believe, m oreover, th at an effort in th at direction w ould be rew arded both with instances in which people occasionally revise th eir theories suitably in accordance with new evidence and even instances in which they behave in the very opposite of the cou n tern o rm ativ e way we believe to be characteristic; that is, instances w ould be found in w hich people reject a w ell-founded theory on the basis of evidence th at is not norm atively sufficient to force its revision. C h ild ren do eventually renounce their faith in S anta C laus; once popular political leaders do fall into disfavor, and a generation of fem inists somehow has m anaged to o v ertu rn popular views of w om en and society. Even scientists som etim es change th eir views! In p art, the issue m ay sim ply be one of b ru te force. No one, certainly not the authors, w ould arg u e th at new evidence or attacks on old evidence can never produce change. O u r co n tention has sim ply been that generally there will be less change th an w ould be dem anded by logical or norm ative standards or that changes will occur m ore slowly th an would result from an unbiased view of the accum ulated evidence. It also seems clear th at the m echanism s which pro m p t belief perseverance som etim es are overcom e w ithout the b ru te force of massive am ounts of probative, disconfirm ing data. D ram atic religious and political conversions, for exam ple, typically are accom plished by quite different m eans. G enerally the subject is pressured to reject entire belief netw orks and to renounce the social, political, or philosophical systems th at produced them . H e is also induced to adopt a new, very biased, interpretive schem a for any new inform ation. Insight therapies sim ilarly attem p t to overcom e beliefs th ro u g h com bining general assaults on belief systems w ith the intro d u ctio n of new explanatory o r inferential schem as. T h e question of w hen and why beliefs yield to evidence has been one of abiding interest to the legions o f psychologists who have studied persuasive co m m unication and attitu d e change. W e cannot pause even to sum m arize the m ajor findings that have em erged from this area (for com prehensive reviews, see M cG u ire 1966; K iesler, C ollins, & M iller 1969). It should be noted that the n o rm ativ e issue has been all b u t ignored by the attitu d e change researchers. W hile we have learned a great deal about which kinds of com ­

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m unicators, messages, audiences, and settings are conducive to attitu d e change, we have learned very little ab o u t the ap p ro p riaten ess o f the degree of change produced by such techniques. Indeed, there is even a paucity of speculation on such issues. It is possible, how ever, to outline two sets o f factors that m ay prom ote ad equate w eighting, or even ‘'o v erw eig h tin g ,” of challenges to o n e ’s existing beliefs. As the read er will readily note, o u r speculations abo u t the factors that determ in e o n e ’s readiness to change beliefs are closely related to o u r previous speculations (chapters 2 an d 3) ab o u t the factors affecting belief form ation in the first place.

E xtra-evidential Features of Inform ation

In previous chapters we m ain tain ed th a t vivid in fo rm atio n , th a t is, concrete, sensory, and personally relevant inform ation, m ay have a disproportionate im pact on beliefs and inferences. T hese sam e factors m ay well influence o u r responsiveness to p articu lar logical o r em pirical challenges to p rio r beliefs. T h u s, the published consensus of diners th at 4‘the fare at C hez Françoise has d eclined” m ay have less im pact on o u r ju d g m en ts an d subsequent behavior th an a single personal experience of an overdone entrée or a vivid, secondhand account of one disastrous m eal. Sim ilarly, public opinion polls show that a few o u tstan d in g and im p o rtan t instances of w rongdoing by people holding high office have dram atically altered the p u b lic’s w illingness to trust the entire class of political leaders. It is w orth noting in this reg ard that participants in the “ d eb riefin g ” studies typically received discrediting inform ation that was relatively dull and abstract com pared to the concrete inform ation that originally induced their beliefs. M ore vivid debriefing procedures— for exam ple, a videotape replay of the past experim ental deception, accom panied by a voice-over account of the key points in the deceptio n — m ight have proved m ore successful.

T he Role o f Causal E xplanations and Scripts: Substitution o f a T heory by a Better T heory

It seems probable that attem pts to discredit beliefs m ay have relatively greater im pact w hen they p ro m p t the use o f plausible theories or “ scrip ts” th at encom pass both the initial inform ation and the su b seq u en t challenge to that inform ation. J u s t as people can use otherw ise unutilized base-rate inform ation when they have a causal theory explaining differences in base rate, people are probably m uch m ore likely to revise theories in response to new evidence w hen they possess a theory th at could account both for initial impressions and for the new , d iscrep an t d ata. A m ere “ scrip t” accounting for

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changes in the n a tu re o f inform ation m ay serve the same purpose. T h e sequence of events com prising a ‘‘false accu satio n ” script, for instance, is surely fam iliar to alm ost all ad u lt subjects, w hether the origins of the script lie in T V m elodram as o r in historic fram e-ups (for exam ple, the D reyfus case). A ccordingly, the discrediting of evidence m ight be m ore successful in overcom ing otherw ise pow erful perseverance m echanism s when it occurs in a setting th at recruits such a false accusation script. It is notable th at one failure to ob tain a perseverance effect (reported by H atv an y , Strack & Ross 1979) occurred in a context in which a “ key w itness” in a videotaped sim ulation of a courtroom trial recanted h er testim ony against the defendant. T o the inv estig ato r’s surprise (b u t n o t th at o f trial lawyers w hom they belatedly consuited) an overcorrection occurred, w ith the d efendant faring b etter than he w ould have in conditions in which no key witness testified against him at all. T h e effectiveness of a variety of procedures for discrediting inform ation also m ay depend on th eir capacity to m ake subjects aw are of some of the processes un d erly in g the perseverance of their beliefs. As noted in o u r discussion o f the Ross, L epper, and H u b b a rd (1975) study, the self-perceptions of subjects who were m erely told of the deceptive n atu re of th eir previous success or failure feedback continued to be influenced by that discredited inform ation. By contrast, th a t tendency was alm ost totally elim inated am ong subjects who also received an explicit theoretical account of the processes th at cause perseverance.

BELIEF PERSEVERANCE: T H E N O RM ATIVE Q U ESTIO N

E ven m ore th an usual, this ch ap ter touched u pon profound and difficult norm ative issues. O u r criticism o f subjects’ b ehavior in the experim ents we have discussed closely follows conventional epistem ological considerations. (See Sklar 1975, for a discussion of the b o u n d ary conditions for a rational belief-conservatism in the face of new evidence.) B ut the perseverance tendencies of subjects in these experim ents were so extrem e as to force consideration o f the possibility th a t the trad itio n al scientific standards m ay not app1y. In p articu lar, it seems possible th at the b eh av io r of subjects, inap>p>rop>riate as it is from the stan d p o in t of ratio n ality in the inferential contexts studied, m ay arise from pmrsuit of im p o rtan t, higher o rd er ep>istemic goals. T w o such possible sup»erordinate goals are (a) the im portance of stability to beliefs and belief-system s, even despúte occasional logical inconsistency and (b) real-w orld co n strain ts on tim e, which m ay prohibit the careful and disp assionate p>erusal an d in teg ratio n o f all new evidence portinent to any p articu lar

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belief (G oldm an 1978). T h e possibility that subjects were acting in accordance with such higher o rd er goals should m ake us relu ctan t to assum e th at their behavior is as in ap p ro p riate as would be im plied by n arro w er considerations of the justification for a p articu la r belief, in a p articu la r context, at a particu lar tim e. O n the other h and, we think it w ould be a m istake to w hitew ash o u r subje c ts’ behavior, or to presum e that it can be un d ersto o d wholly in term s of such w orthy higher o rd er goals. P eo p le’s confirm ation biases in th e ir approach to the recall and generation of data and th eir facile and overconfident approach to causal analysis are too well docum ented to ju stify such tolerance. F ortunately, the norm ative questions here adm it at least partial resolution by (adm ittedly arduous) em pirical m eans: W ould people be so inclined to persevere in their beliefs if they knew about th eir confirm ation biases and overconfident causal analyses? A nd if they did not persevere as m u ch , once they had a full u n d erstan d in g of these tendencies, would such h igher o rd er goals as belief-system stability suffer for it?

SUM M ARY

People tend to persevere in th eir beliefs well beyond the point at which logical and evidential considerations can sustain them . 1. W hen people en co u n ter probative evidence p ertin en t to p rio r beliefs they tend to apply asym m etric critical stan d ard s to supportive and opposing evidence and tend to becom e m ore confident of a belief in response to a set of m ixed evidence which norm atively should serve to low er confidence. 2. People do not observe the “ co m m u tativ ity ” rule in response to sequentially presented evidence. Instead, early-presented evidence seem s to create theories w hich are not revised sufficiently in response to laterpresented, conflicting evidence. 3. Beliefs tend to sustain them selves even despite the total d iscrediting of the evidence that produced the beliefs initially. Belief perseverance som etim es seems to occur because people have an em otional com m itm ent to the belief. P erseverance is likely even w hen there is no such investm ent, how ever, because (a) people tend to seek o u t, recall, and interpret evidence in a m a n n er that sustains beliefs, (b) they readily invent causal explanations of initial evidence in which they then place too m uch confidence, and (c) they act upon th eir beliefs in a way that m akes them selfconfirm ing. P eople’s tendencies to persevere in th eir beliefs are so striking as to raise the possibility th at such perseverance serves goals th at m ay be m ore fundam ental and im p o rtan t than holding correct views of p articu la r issues.

part III

INFERENTIAL ERRORS: THEIR CAUSES, CONSEQUENCES, AND CURES

9 the lay scientist self-examined

The mental, like the physical, is not necessarily in reality just what it appears to us to be.

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Sigmund Freud.

O u r p rim ary focus has been on the lay scientist’s view of his peers and his en v iro n m en t. N ow it is tim e to consider w hat happens w hen the lay scientist tu rn s his atten tio n inw ard to m ake ju d g m en ts of him self—of the n atu re of his personal dispositions, his feelings an d attitu d es, an d , m ost im portantly, of the d eterm in an ts o f his own behavior. T h e general thesis offered in this ch ap ter is a sim ple one an d is largely anticipated by B ern’s (1965, 1967, 1972) self-perception theory. W e m ain tain th a t know ledge of the self is produced by the sam e strategies as know ledge of o th er social objects, and is thus prone to essentially the sam e sorts of bias and erro r. W e do not deny th at the acto r an d the observer som etim es differ in th eir beliefs abo u t the actor. O u r co n tention, rath er, is that accurate perceptions o f self an d accu rate perceptions o f others ultim ately depend on the suecessful perform an ce of the sam e “ scientific” tasks— th at is, collecting, coding, an d recalling d a ta , assessing covariations, inferring causal relationships, an d testing hypotheses. 195

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Actors seem to have one sort of d ata available to them that observers do not, nam ely their own private thoughts an d experiences. A key issue is the extent to w hich people have access to a private source of data. T o w hat sorts of m ental events do people have genuine privileged access? W h at ad v an tag e does such access give them in characterizing them selves an d explaining their actions? In keeping w ith the overall organization of this book, we begin by considering people’s success in perform ing relatively elem entary tasks involving self-characterization and then tu rn o u r atten tio n to the q u estion of people’s accuracy in assessing the m ediators or causes of their own behavior.

CHARACTERIZING O N E ’S OWN BEHAVIORAL DISPO SITIO N S

W hen we considered in chapter 4 the question of how accurately the layperson can characterize objects generally, we said that som e ch aracterizatio n s were extrem ely accurate w hen ju d g e d against objective criteria, others w ere clearly inaccurate w hen ju d g e d by such criteria, and still o th ers— perh ap s the m ajority of characterizations— sim ply did not have available objective criteria for com parison. T hese problem s seem even m ore acute for the ch aracterization of the self. Z im bardo (1977) found, for exam ple, th a t m ost people believe that they are “ sh y .” H ow could one assess the accuracy of such claim s, either for the m ajority taken as a whole or for any given m em ber of the selfdescribed “ shy” m ajority? “ Shyness” w ould seem to have both experiential and behavioral referents. Suppose the proverbial back-slapping extro v ert, the sort found sw inging from chandeliers at a party , asserts that he is “ s h y .” A re there reasonable grounds on w hich to contest Ilis right to assert th at he experiences em otions that could be described as “ shyness” — even w hen (perhaps especially when) he is found sw inging from the chandelier? Suppose he characterizes him self as behaviorally shy? C an we safely co ntradict him even then? W hat if he asserts that he avoids blind dates, can n o t reveal him self even to intim ates, an d w ould sooner die th an try to give a speech? T h e problem is a general one. N eith er “ objective” behavioral m easures nor the assessm ents of peers or experts offer a satisfactory “ c rite rio n ” th at can be used to evaluate a p erso n ’s self-assessm ents. T h is is not to deny that the am ount of agreement am ong the various sources can be explored, an d th at dem onstrations of convergence, or divergence, can be interesting and revealing from m any standpoints. Such dem o n stratio n s can offer clues ab o u t sim ilarities or differences in the d ata, m ethods of analysis, perspectives, an d theories em ployed by the various evaluators. (See, for exam ple, Block 1961; D ornsbusch, H astorf, R ich ard so n , M uzzy, and V reelan d 1965; G oldberg

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1978; N o rm an and G oldberg 1966; N isbett, C ap u to , L egant and M aracek 1973.) But the issue of relative or absolute accuracyy or in o th er w ords, the ‘‘v alid ity ” issue, rem ains refractory. W hile we cannot co m m en t authoritatively about the overall accuracy of the la y p erso n ’s self-characterizations, we can say som ething about the determinants of such characterizations. P eo p le’s characterizations of them selves, like their characterizatio n s of the objects and events that com prise th eir env iro n m en t, are heavily based on p rio r theories and socially tran sm itted preconceptions. A nd as we have docum ented m ore form ally in chapter 8, the ind iv id u al’s im pressions and ju d g m en ts can survive seem ingly potent em pirical challenges. T h e re is m uch anecdotal evidence for this generalization. O n e of the au th o rs, in his first years of teaching, was am azed and disturbed by the tendency of m any of his fem ale u n d erg rad u ate students to m ain tain negative stereotypes of their m athem atical abilities even though their successes belied such stereotypes. O ften , a stu d en t w ould succeed adm irably in a statistics course that, on the first day of class, she had tearfully predicted she would fail. Such a studen t usually proved capable of readily assim ilating h er unanticipated success to h er previous view of herself, assigning credit to the lucidity and patience of the in stru cto r, to h er strenuous efforts, or to the ‘‘easiness” of the course. It was quite difficult to get such a student to entertain the possibility th at h er previous theory about herself was sim ply w rong, that it had been based u pon a com bination of insufficient data and sex-role stereotypes that h er academ ic choices heretofore had left largely unchallenged. V ery recently a n u m b e r of studies have begun to deal explicitly w ith possible effects on the processing of inform ation about the self produced by o n e ’s theories or schem as about the self. For exam ple, M ark u s (1977) used several criteria to distinguish subjects who had form ed or had not form ed ‘ ‘self-schem as,” (the in v estig ato r’s term for dom ain-specific cognitive generalizations about the self, presum ably derived from past experience). She then d em o n strated th at the subjects who possessed self-schemas for a particular dom ain (for exam ple, who viewed them selves as either “ d ep en d e n t” or “ in d e p e n d e n t” ) m ore rapidly processed relevant inform ation about them selves, m ore readily retrieved relevant behavioral evidence, m ore confidently predicted new responses in the dom ain, and showed greater resistance to inform ation th at ostensibly contradicted their self-characterizations. Such “ econom ies” arising from the possession of schem as do have a cost, as we have noted in earlier chapters. T h a t cost is the schem a-holder’s penchant to overassim ilate new in form ation to the preexisting schem a, thereby sustaining and even stren g th en in g that schem a with inform ation that would offer no such support if it w ere processed w ithout prejudice. B eyond th eir im pact on the coding of am biguous inform ation, schem as

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about the self, like schem as about o ther people, objects, or events, can be shown to produce distortions in m em ory. R ogers, R ogers, an d K u ip e r (1978) were able to observe the sam e kinds of biases and distortions in recall of selfrelevant inform ation th at C a n to r an d M ischel (1977, in press) and others (for exam ple, T sujim o to 1979; T su jim o to , W ilde, & R o b ertso n 1979) were able to dem onstrate for recall of inform ation ab o u t “ p ro to ty p ic” others. R ogers an d colleagues tested subjects’ recall of adjectives an d found th at the incidence of “ false positives” (that is, instances in which adjectives were “ recalled ” th at had not been presented initially) tended to increase progressively as the adjectives in question becam e m ore an d m ore self-descriptive. In a related vein, M ischel, E bbesen, and Zeiss (1976) d em o n strated th at experim entally m anipulated expectations about the self can produce sim ilar m em ory biases. T h e ir subjects first received an initial experience of either success or failure on a test of m ental abilities, coupled w ith a set of instruetions that led them to expect either future success, future failure, or no subsequent testing. All subjects next were exposed to an equal am o u n t of new positive and negative inform ation about their personalities and then w ere given a m em ory test on th at inform ation. As predicted, subjects who expected to succeed rath er th an to fail were inclined to rem em b er th eir p u rp o rted personal assets b etter than their alleged liabilities. In d eed , the effects of expectancy overshadow ed those of actual experience; only w hen subjects h ad no expectation of future success or failure did th eir past experience have any influence at all on their recall of assets versus liabilities. T h e clinical literatu re, as one m ight expect, also has m any accounts of the capacity of people’s preconceptions of them selves to bias th eir m em ories or interpretation s of event an d thereby to influence th eir expectations and subsequent behavior. P articularly in teresting are findings on the phenom enon of depression. V arious investigators have suggested th at depressed individuals m ay be less interpersonally or socially skillful th an “ nondepressed” persons (for exam ple, Libet & Lew insohn 1973). O th ers have suggested that depressed individuals m ay be inclined to perceive th eir attrib u tes and skills in an “ unrealistically n eg ativ e” m a n n e r (cf. Beck 1967). T o disentangle possible m isperceptions from actual deficiencies, L ew insohn, M ischel, C haplin, and B arton (1980) com pared self-ratings an d peer ratin g s for three types of people: depressed individuals, individuals w ith psychiatric problem s other than depression, and no rm al controls. R atin g s w ere m ade after group interactions. As expected, the depressed individuals rated them selves, and also were rated by others, as less socially co m petent th an the two control groups. Surprisingly, how ever it was not the depressed group th at who showed a tendency to m isperceive the actual state of affairs; self-assessm ents by that group corresponded well w ith the perceptions of them offered by others. R ath er, it was the two control groups w ho were p rone to e rr, w ith both groups seeing them selves m ore positively th a n they w ere seen by others. It is thus possible that unrealistically positive self-schem as or o th er illu­

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sions ab o u t the self, together w ith the processing biases they can engender, m ay be m ore socially adaptive th an are totally accurate self-perceptions. T his possibility is fascinating, an d it is beg in n in g to receive the atten tio n it deserves (for exam ple, Seligm an 1978). F or now, how ever, we need only reem phasize th a t self-characterizations, like social characterizations, ap p ear to be heavily influenced by preconceptions or theories about the self.

ASSESSING O N E ’S OWN EM O TIONS AND A T T IT U D E S

P erhaps the m ost energetically researched aspect of self-knowledge in recent years has been the ability of people to “ k n o w ,” that is, to label or to evaluate, th e ir own em otions, attitu d es, an d o ther in tern al states. In two increasingly convergent an d now very fam iliar areas of investigation, Stanley S chachter (1966, 1970, 1971; S chachter & S inger 1962), studying em otions an d D aryl Bern (1965, 1967, 1972), studying attitudes, arriv ed at essentially the sam e radical conclusion. Both investigators, in defiance of both existing psychological theory an d intu itio n , questioned the extent to which selfassessm ents of em otions an d attitudes are the product of direct introspection. Both theorists stressed instead the role played by causal inference in such assessm ents.

E m otion al L ab elin g and Causal A ttrib ution

S ch ach ter’s research on the effects of cognitive or situational cues on the labeling of artificially p ro d u ced states of em otion (Schachter & Singer 1962; S chachter & W heeler 1962) an d scores of follow-up studies utilizing naturally occu rrin g em otional states (for exam ple, N isbett & Schachter 1966; Ross, R o d in , & Z im b ard o 1969; etc.) all illustrated the extent to w hich the selfassessm ent of em otion m ay be an attributional process. O nce the individual becom es aw are of his own state of physiological arousal, the labeling of that state— an d the subjective experiences, self-reports, and em otionally relevant b eh av io r that accom pany such lab elin g -r‫־‬is the result of a search for a plausible cause of the arousal. P oten tial arousal sources m ight include external events (a grow ling dog, a com e-hither stare, a m endacious politician) or spontaneous cognitions (the th o u g h t of an up co m in g jo b interview , the m em ory of an em b arrassin g incident) or a co m b in atio n of the two sorts of stim uli. In both cases, the attrib u tio n is m ade on the basis of the availability and plausibility of the arousal sources u n d e r consideration. T h e result is a high degree of em otional “ plasticity ” ; if the actual source of o n e ’s arousal is not readily available an d reasonably plausible, the individual is apt to label his

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em otional state in term s of w hatever sources are easily available an d plausible. T his account of em otional labeling has several im p o rtan t im plications. W hen the actual source of the lay scientist’s arousal is u n am b ig u o u s, he is ap t to label his state correctly and to respond accordingly. But when chance, clever experim enters, or the com plexities of o n e ’s em otional life contrive situations in w hich the actual sources of the lay scientist’s arousal are disguised, so that incorrect alternatives are m ore available or plausible than the correct ones, he is likely to m islabel his state. By holding co n stan t su b jects’ em otional arousal but m an ip u latin g the source to w hich it m ay be plausibly attrib u ted , experim enters have been able to produce either a h eig h ten in g or lessening of m any states, including fearfulness, aggressiveness, playfulness, and sexuality. T o take ju st one exam ple of m any, C an to r, Zillm an and B ryant (1975) have shown that the rated attractiveness o f nudes can be influenced by the degree of arousal produced by an extraneous source an d by the degree to which the arousal is incorrectly attrib u ted to the nudes rath e r th an correctly attrib u ted to the extraneous arousal source. M ale subjects w ere req u ired to ride an exercycle w ith sufficient vigor to induce a high degree of physiological arousal. T h e fact of the arousal and its source were ap p are n t to the subjects im m ediately after the exercise. A fter a few m inutes, how ever, subjects w ere no longer able to report arousal even though, as m easured by physiological indicators, they were still aroused. N udes exam ined d u rin g this period w ere rated as m ore attractive than those exam ined im m ediately after exercise (when subjects knew that they were still aroused from their exertions) or than those exam ined at a still later period (w hen there was no extraneous arousal to be m isattributed). S chachter’s essential insight was that em otional experience and behavior reflect a considerable am o u n t of w hat can only be term ed “ causal in feren ce” and that the role of any m ore direct aw areness of the n atu re or antecedents of that state is at best lim ited. P eople’s labeling of their em otional states, in other w ords, depends on an analysis of evidence conducted in the light of preconceived theories ab o u t w hich antecedents produce w hich states and w hich states are the product of which antecedents.

Inferences about O n e’s O wn A ttitudes

Bern’s w ork on the processes by w hich individuals com e to know their own attitudes had a very different startin g point. H e was influenced by the S kinnerian analysis (1953, 1957) of self-reference b eh av io r (an d by philosophical treatm ents of the sam e problem by W ittgenstein an d R yle). Bern was concerned at first with self-ascriptions of attitu d e (cf. Bern 1964, 1965, 1967), bu t he soon m ade the connection betw een his own research and the em erging Schachterian lite ra tu re — so th at in his statem en t of selfperception theory (1972) Bern explicitly chose to em brace “ attitu d es, em o ­

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tions, an d other in tern al states” w ithin the sam e conceptual fram ew ork. Such states, Bern arg u ed , are know n to the individual ‘‘partially by inferring them from observations of his own overt behavior an d /o r the circum stances in w hich this behav io r o ccu rs” (1972, p. 2). A n im p o rtan t derivation is that “ to the extent that in tern al cues are w eak, am biguous, or u n in terp retab le, the individual is functionally in the sam e position as an outside observer who m ust necessarily rely upon those sam e external cues to infer the in d iv id u al’s inner states” (p. 2). H e th en proceeded to d em o n strate, in a variety of contexts, how m uch such “ external cues” — an d how little any “ internal cues” — contrib u te to acto rs’ self-reports of th eir attitudes. T h e initial research context for B ern’s theory was the dissonance or insufficient justificatio n p arad ig m . In these experim ents, it will be recalled from C h a p te r 6, experim ental subjects are required to perform some action that is in congruent w ith their p rio r beliefs. W hen subjects are adequately com pensated for their co u n terattitu d in al behavior, for exam ple, w hen they are offered large m on etary paym ents, th eir attitu d es tow ard the object to which the beh av io r was directed typically und erg o no change. W hen subjects are not ad equately com pensated for th eir co u n terattitu d in al behavior, their attitudes tow ard the object typically change in a congruent direction, so as to m ake attitudes “ co n so n an t” w ith behavior. Bern found th at in “ interpersonal replications” of such experim ents, in w hich protocols describing the various experim ental conditions were presented to “ o b serv er” subjects, these observers m ade the sam e ju d g m en ts of a cto rs’ attitud es as did the actors them selves. O bservers who read about the b ehavior of adequately com pensated actors inferred that acto rs’ beliefs were less co n g ru en t w ith th eir actions th an did observers who read about the b ehavior of inadequately com pensated actors. Bern argued that this result indicates th at actors assess th eir own und erly in g attitudes in a m a n n er very sim ilar to observers who have w itnessed (or sim ply read about) the acto rs’ behavior and the context in w hich it occurred. T h u s, w hen atten d in g pressures and constraints seem sufficient to induce the actor to behave in a p articu lar m a n n er (for exam ple, to present a p articu lar u n p o p u lar view point in a speech or essay, or even to en d u re electric shock), n eith er the actors them selves no r observers p resum e that the acto rs’ private views correspond to th eir overt actions. O n the o ther h an d , w hen pressures and constraints do not seem sufficient to produce the acto rs’ b ehavior (even w hen the situational pressures are, in fact, pow erful enough to control the behavior of the vast majo rity of subjects), actors and observers both m ake the sam e inferences about the acto rs’ beliefs. Both actors and observers overestim ate the degree of congruence betw een the a c to r’s priv ate attitudes and his overt behavior. S ubsequent research has provided ab u n d a n t evidence for the influence of such causal analyses on acto rs’ assessm ents of th eir own attitudes. Some of this research was discussed in ch ap ter 6. For exam ple, the nursery school children in the L ep p er, G reene, and N isbett (1973) experim ent, who were given an extrinsic in d u cem en t to play w ith m agic m arkers, showed less in ­

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terest in playing w ith m agic m arkers on later occasions th a n did children who had never been given such an inducem ent. O ffering a B em ian analysis, Lepp er and colleagues argued that the children who received the extrinsic inducem ent to play with the m agic m arkers inferred th at they h ad done so because of the inducem ent and not because of th eir intrinsic interest in the activity. H av in g inferred that they h ad relatively little intrinsic interest in playing with m agic m arkers, they were less inclined to do so w hen a subsequent o p p o rtu n ity arose. It is not necessary for us to spend m ore tim e on the very large a m o u n t of controversial literatu re initiated by B ern’s self-perception theory. It will suffice to state two relatively uncontroversial conclusions: (1) P eo p le’s priv ate, introspective access to their attitudes is not so direct and u n e rrin g as to preem pt the consideration of such public events as o n e ’s own b eh av io r tow ard the object and the pressures an d constraints in the situation in w hich the behavior occurred. (2) It has proved extrem ely difficult for critics to dem onstrate convincingly th at the process by w hich actors assess th eir attitudes is fundam entally different from that em ployed by observers. (T his is tru e even if one accepts the dissonance th eo rists’ claim th at, for actors, the process is triggered by a painful m otivational state [see Z a n n a & C o o p er 1976]). O u r discussion of S chachter’s and B ern’s contrib u tio n s anticipates the rem ainder of this chapter in which we will exam ine the lay scientist’s assessm ent of the causes of his own behavior. Both S chachter an d Bern b eg an by considering people’s ability to assess their feelings or beliefs b u t ended by exam ining their ability to m ake causal inferences. T h e question “ W h at em otion am I feeling?” becam e “ W h at stim ulus is causing m e to feel aro u sed ?” Sim ilarly the question “ W h at is m y attitu d e tow ard A ?” becam e “ W h at forces and constraints are influencing m y b eh av io r tow ard X y an d are they sufficient to account for my b eh av io r?” It is clear that people’s ability to assess their feelings and attitudes will tu rn out to be largely d ep en d en t on their ability to perform such causal analyses.

CAUSAL EXPLANATIONS OF O N E ’S OWN BEHAVIOR

W hy were you so depressed last week? W hy did you hire M s. D avis w hen M s. Peters seem ed so m uch b etter qualified for the position? W hy d id n ’t you help the old m an lying on the sidewalk? W hy did you bu y a Porsche instead of a Pontiac? W hy did you refuse the attractiv e jo b offer from K ansas? People answ er such queries every day, som etim es w ith a concession of u n certainty, som etim es w ith confidence that they are revealing a sim ple truth.

The Raw Data for Causal Explanations W hy do we often feel convinced of the accuracy of such accounts, and why are we so tolerant of o th er p eo p le’s sim ilar accounts? T h e answ er appears to be that we believe, quite correctly, th a t each of us is privy to a w ealth of d ata p ertin en t to the gen eratio n of such accounts. W e know m any personal historical facts; we often know w hat thoughts occupied o u r attention at the tim e the behavio r occurred; we know o f w hich facts in the external w orld we were cognizant an d o f which we were not cognizant; an d we know ab o u t the plans and goals th at we believed the b ehavior w ould serve. B ut how well founded is the assum ption that access to such d ata g u aran tees the accuracy of the a cto r’s causal explanations for his behavior. Access to large am o u n ts of data does not p rev en t us from m aking errors in o u r causal explanations of external physical and social events, as chapter 6 illustrated. It seems reasonable to suspect th at o u r confidence in the causal explanations we offer ab o u t o u r behavior m ay sim ply be a special case of o u r largely un fo u n d ed confidence in the accuracy of o u r causal explanations in general. K now ing th at an event has occurred, an d having some data about antecedent events, o u r fertile im aginations seize on one or two of the antecedent events, and link them in a causal chain to the effect. H av in g little recognition of the facility w ith which we generate such explanations, and having little notion o f the size of the set of causal explanations that we w ould find equally satisfactory, we are content w ith the explanation. It m ight be protested th at m atters are different for explanations of o u r ow n behavior because we have m uch m ore know ledge of the antecedent events than we do for other p eople’s behavior. But should such know ledge be reg ard ed as literally com plete, or nearly so? T h ere is good reason to believe that it is not, an d th at regardless of the level at w hich a “ m ental e v e n t” is defined, access to such events is spotty and im perfect. T h e events u n d erly in g ju d g m e n t and behavior, virtually all theorists w ould agree, are ultim ately reducible to physiological occurrences in the central nervous system . T h e notion o f direct access to these events is surely as peculiar as w ould be the assertion th at we have ‘‘direct access” to the workings of the eyeball or the adrenal g lan d — both of which do ultim ately produce conscious experiences. A t a som ew hat h igher level of analysis, there are a large n u m b er of m ental states and events w hich clearly influence beliefs an d behavior b u t to which no one w ould m ain tain th at we have direct access. T h e philosopher Steven Stich (1979) labeled these “ subdoxastic sta te s,” th at is, states which influence an d u nderlie beliefs b u t w hich are not them selves beliefs. For exam ple, o u r ability to ju d g e the relative distance of objects is dep en d en t on a great m any external factors, b u t m any of these are not generally accom panied by any p henom enal rep resen tatio n . T hese factors include perspective, surface textu re, the perception of edges an d corners, occlusion, illum ination gradients, 203

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and stereopsis. It was not until the R enaissance that m any of these factors were recognized as influencing o u r perceptions of d epth. As an o th er exam ple, consider the rules of g ram m ar that underlie o u r ability to produce and com prehend speech. T hese rules are an enorm ously com plicated and largely inaccessible netw ork. T h o u g h people use the netw ork constantly an d w ith n earperfect accuracy, an d though educated speakers m ay have ,in d ep en d en tly stored, verbally represented know ledge of some of the rules, even the m ost educated people do not have an y th in g like com plete know ledge of this network. T h e question of ju st what the rules of g ra m m a r m ight be is cu rren tly a m atter of intense debate am ong people who have spent a lifetim e stu dying those rules. Suppose we restrict ourselves to m ental events at a still higher level of analysis, to events that m any theorists w ould reg ard as the m ost crucial ones m ediating behavior— the percepts and m eanings, how ever reached. It seems likely that we have access only to some o f these an d th at som e percepts and m eanings are not represented phenom enally. (See Jay n es 1976 for a com prehensive discussion.) R esearch on sublim inal p erception, review ed by Erdelyi (1974) and D ixon (1971), has m ade a n u m b e r of theoretical and m ethodological advances. It now seems entirely likely th at we are capable of 4‘perceiving’’ a stim ulus, w hich then influences o u r behavior, while at the sam e tim e showing no ability to report any p henom enal rep resen tatio n of the stim ulus, even at the very m om ent th at it is presented. A single illustration of the 44unperceived p ercep t” should suffice. A fter spending some tim e in a room w ith a loudly ticking g ran d fath er clock, there will be no ph en o m en al representation and no aw areness of the ticking. T h e percept is nonetheless present at a subphenom enal level. T h is can be shown by the sim ple experim ent of stopping the clock. N orm ally, there will be an im m ediate o rien tin g response. T h u s the set of m ental events for which we do not have an y phenom enal representation includes m any events th a t m ay properly be called percepts. T o the extent th at such subconscious percepts influence o u r behavior, it is clear that causal accounts m ay be incom plete. A t least some “ m ean in g s” of stim uli and events are accessible, b u t it seems clear that it is norm ally the case that not all m eanings of a p articu la r stim ulus are represented phenom enally. If we are asked w hether a specific stim ulus has a given m eaning for us, an answ er som etim es req u ires som e thought. Some stim uli are very rich in th eir associative netw orks, an d these netw orks and all they encom pass are not norm ally spontaneously available to consciousness. T o the extent that some of these subtle m eanings influence behavior, then o u r causal accounts m ay be partially incorrect. If we are unaw are of so m any m ental events, then a causal account of the m ental process u n d erlying a behavior m ust be, at the very least, incom plete. But there is m ore to be said of o u r access to m ental processes. M a n d le r has argued th at a 44process” is by definition a theoretical construct, an d th a t, on logical grounds, there can be no direct conscious access to a m ental process.

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As M an d ler explained: 4‘T h in k in g ’ ’ or cognition o r inform ation processing for the psychologist is a term that refers to theoretical processes, complex transferm ations on internal and external objects, events, and relations. These processes are not conscious; they are, in the first instance, constructions generated by the psychological theorist. By definition the conscious individual cannot be conscious— in any acceptable sense of the term — of theoretical processes invoked to explain his actions. (1975 p. 231) —For readers reluctant to agree w ith M an d ler that logically there can be no direct conscious access to m ental processes, the following argum ent may be persu asiv e.A t is not controversial that causal accounts for all rzorcmental processes are theoretically guided inferences an d not direct observations. Even so simple a causal account as an explanation of the event of a stone’s d ro p p in g to earth w hen u n su p p o rted is a strictly theoretical enterprise and is one for which accuracy is chiefly a function of the quality of o n e’s theories rath e r than of the quality of o n e ’s observations. T h u s a prim itive person or a child m ight say that the stone dropped because it “ w anted to .” A scientist in A ristotle’s tim e m ight have said the stone dropped because it had the property of gravity. A N ew tonian scientist would have said that the stone dropped because it existed in a field of forces of which the most relevant were the mass of the stone, the e a rth ’s gravitational pull, an d the relative insubstantiality of the in terv en in g m edium , nam ely, air. N one of the accounts is an observation o f a causal process, since causal processes cannot be observed; instead they are theory-guided inferences. In M a n d le r’s view and in ours, the same is true for reports of m ental processes. A m ental process, that is, the m eans by which one m ental event influences an o th er, cannot be observed but only inferred, and the quality of the inference is at least as dependent on the quality of o n e’s psychological theories as on the q u an tity of data observed. T h ere are strong theoretical and logical grounds for d oubting the extent to which o u r reports of the causes of our own behavior could be expected to be universally accurate. W e lack phenom enal representations of m any potentially influential m ental events, an d such phenom enal givens as exist do not suffice to reveal, b u t allow us only to infer, the natu re of the processes underlying behavior. T h ere also are, as will be seen, em pirical grounds for doubting the accuracy of o u r causal accounts. T h e Accuracy o f Causal E xplanations

As it happens, the self-perception research discussed earlier provides a great deal of evidence on the question of accuracy. Both S chachter’s work on em otions and the dissonance or insufficient justification work offered compelling evidence of inaccuracy. Subjects can be m ade to m isattrib u te exogenously induced arousal to salient en v iro n m en tal stim uli, and can be m ade to m isattrib u te arousal produced by en v ironm ental stim uli to alleged ex­

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ogenous sources (for exam ple, a sugar-pill placebo w hich the subject is told is a physiological stim ulant). Insufficient justificatio n studies “ w o rk ,” as we noted in chapter 6, only because of an incorrect causal attrib u tio n . T h e subject is virtually forced, by social pressure from an ex p erim en ter, to perform some behavior (for exam ple, giving a co u n terattitu d in al speech) w hich he would rath er not perform . T h e subject then falls into the trap of attrib u tin g the behavior to his own p rio r beliefs because he does not u n d erstan d th a t the real cause of his behavior is the subtle b u t pow erful social pressure generated by the experim enter. As N isbett and W ilson (1977a) pointed out, inform al, u n p u b lish ed evidence from both of the above research trad itio n s showed th at su b jects’ causal explanations following their p articip atio n in such studies failed completely to take account of the factors th at actually p ro m p ted their behavior. Subjects did not refer in any way to the stim ulus conditions th a t p ro d u ced the dram atic effects on their behavior, let alone co nstruct a co h eren t causal account incorporating such stim uli. T h is evidence has lim ited value, how ever, for questions ab o u t the degree of accuracy to be expected of causal accounts generally. Investigators in the em otional labeling and insufficient justificatio n studies go to u n u su al lengths to confuse subjects about the true causes of their behavior. In the form er, the experim enter cleverly arran g es contingencies so th a t a subject will find him self inexplicably aroused, or aroused u n d er circum stances w here the real explanation for his arousal is less plausible th an others w hich the experim enter has suggested. In the latter, the com bined w isdom of the highpressure salesm an and the lore of experim ental social psychology are p u t to work to create an illusion th at behavior is chosen w hen in fact it has been coerced. T hese studies m ake the im p o rtan t point th at people can be bam boozled about the true causes of their behavior, b u t they say little ab o u t the degree of accuracy to be expected u n d er less stage-m anaged conditions. T o answ er the m ore general question, N isbett an d W ilson (1977a, 1977b; W ilson & N isbett 1978) conducted a series of studies assessing the accuracy of causal explanations. A wide range of responses was ex am in ed , ineluding evaluations, ju d g m en ts, and choices. Each of the behaviors and behavior settings studied was a ro u tin e type en co u n tered frequently in daily life. D eception of any sort was used in only a few of the studies and was lim ited to “ cover sto ries.” In addition, care was taken to m inim ize egoinvolvem ent of the sort th at m ig h t p ro m p t subjects to disguise from them selves or others the true causes of th eir behavior. D espite these precautions, subjects proved to be rem arkably inaccurate in th eir causal reports. Stim ulus factors th at had a p ronounced effect on b eh av io r w ere denied to have had any effect on behavior, and stim ulus factors th at had no detectable effect were asserted to have been influential. Because the experim ents have been described in general by N isb ett and W ilson (1977a) and in detail by W ilson and N isbett (1978), we will only sketch them here.

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Before we do so, we should p o in t out th at N isbett an d W ilson did not select h ap h azard ly the behaviors and settings studied. Instead, they deliberately tried to m an ip u late some causal factors which they believed th eir subjects incorrectly w ould reg ard as noninfluential, an d others which would in fact be noninfluential b u t which subjects w ould be apt to regard as effective. N isbett an d W ilson were notably unsuccessful in th eir attem pt. T hey tu rn ed out to be no better th an th eir subjects at estim atin g which stim uli actually w ould influence, o r fail to influence, the subjects’ behavior. In fact, consistent w ith o u r later arg u m en ts ab o u t the basis o f subjects’ reports, N isb e tt’s and W ilso n ’s predictions o f the effects of the stim uli they m an ip u lated w ere m uch closer to subjects’ erroneous reports about their effects th a n to the actual effects revealed by statistical analysis.

F ailure to Report In flu en tial Factors

Failure to recognize semantic cuing effects. In one study, subjects m em orized a series of w ord pairs (for exam ple, ‘ ‘o cean-m oon” ), some of which w ere intended to increase the likelihood of certain sem antic associates in a later w ord association task (for exam ple, “ T id e ” in response to the category “ d e te rg e n t” ). Eight such sem antic cues were studied, and all eight served to enhance the likelihood of the target association. O n the average, the effect o f the sem antic cue was to double the likelihood o f the target w ord being given as an associate, from 10 percent for control w ords to 20 percent for cued w ords. D espite this p ro n o u n ced effect of the sem antic cues, subjects alm ost never referred spontaneously to the initial w ord p air w hen later asked why they h ad given the targ et as an association to the category stim ulus. In both cued an d u n cu ed conditions, subjects tended to cite th eir fam iliarity w ith the targ et, th e ir liking or disliking for the target, o r som e other personal reaction to it, as the reason for its com ing to m ind. W h en specifically asked about the effects of the w ord pairs, m ost subjects denied such an effect. In addition, frequency of rep o rted effects was u n related to actual strength of the effects. T h u s, for m ost targets, few er subjects reported an effect of the w ord p air than w ere actually influenced by it, while for o ther targets, m ore subjects reported an effect th an w ere actually influenced by it. F ailure to recognize position effects. In a second series of studies, passers-by in a shopping mall w ere invited to exam ine an array of consum er goods (four nightgow ns in one study, four identical nylon pantyhose in an o th er) and to rate their q u ality. T h ere was a pro n o u n ced position effect on evaluations, such th at the right-m ost garm ents were heavily preferred to the left-m ost garm en ts. W hen questioned ab o u t the effect of the g arm en ts’ position on th eir choices, virtually all subjects denied such an influence (usually w ith a tone of annoyance or of concern for the ex p erim en ter’s sanity).

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F ailure to recognize “ anchoring ” effects. In a th ird series of studies, subjects were asked to guess w hat the average b ehavior of U n iv ersity of M ichigan students would be in several different experim ents. Some subjects were given an “ an ch o r” in the form o f know ledge of the b eh av io r of one particu lar “ random ly chosen su b ject.” A nchoring effects on predicted m ean values ranged, across the various experim ents, from very large, th at is, a pronounced “ p u ll” on subjects’ predictions in the direction of the an ch o r value to slight “ an tian ch o rin g ” effects, th at is, m o v em en t aw ay from the an ch o r value. Im m ediately after m aking th eir estim ates, subjects were asked ab o u t the extent to w hich they had relied on know ledge of the p articu la r in d iv id u al’s behavior in m aking these estim ates. Subjects rep o rted m o d erate u tilization of the anchor value in all conditions. T h ey reported the sam e degree of utilization of the anchor value for experim ents in w hich it had not been used at all as they did for experim ents in which it had heavily influenced th eir estim ates. Failure to recognize the effects of an individual ’s personality on reactions to his physical characteristics. O n e ex p erim en t by N isb ett and W ilson (1977b) suggested th at people m ay not m erely fail to recognize an imp o rtan t causal influence on their behavior b u t actually m ay in v ert the tru e causal direction in their accounts. T h eir subjects p articip ated in a d em o n stration of the fam iliar “ halo effect” in interpersonal p erception. Subjects w atched a videotaped interview w ith a Belgian psychology in stru c to r who spoke English w ith a m oderately heavy accent. H a lf of the subjects saw the instructor answ ering questions about his teaching practices an d philosophy of education in a pleasant, agreeable, and enthusiastic m a n n er (w arm condition), while the other half saw him acting like an autocratic m a rtin e t who seemed rigid, intolerant, an d distrustful of his students (cold condition). Subjects then rated the in stru c to r’s likableness an d also evaluated th ree attributes th at were in v arian t across the two ex p erim en tal conditions: his physical appearance, his m annerism s, and his accent. N ot surprisingly, subjects who saw the w arm version of the interview liked the in stru cto r m uch better than those who saw the cold version did. F u rth erm o re , th eir ratin g s of his attributes showed a very m arked “ halo effect.” T h e “ w a rm ” in stru c to r’s appearance, m annerism s, and accent were rated as attractive, b u t w hen the sam e objectively in v arian t features w ere m anifested by the “ cold te a c h e r,” they were rated as irritating. Some of the subjects in each experim ental condition w ere asked w h eth er their liking for the teacher h ad influenced th eir ratings of the three attrib u tes, while the rem ain d er were asked the opposite q u estion, th at is, w h eth er their liking for each of the three attrib u tes h ad influenced th eir liking for the teacher. T h e results showed a p attern of reports th at, w hile highly reasonable and plausible, were clearly at odds w ith the facts ab o u t the actual d irection of influence. Subjects in both w arm and cold conditions strongly denied th a t th eir overall liking for the in stru cto r had influenced th eir ratin g s of the three attributes. Subjects who saw the w arm version also denied th at th eir liking of

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those attrib u tes h ad influenced their overall liking of the instructor. O nly subjects who saw the cold version consistently reported a causal influence. T h ey claim ed that their dislike of the in s tru c to rs attrib u tes had low ered their overall liking of him . In short, it w ould ap p ear these subjects inverted the true causal relationship. T h e ir dislike for the “ cold55 teacher had m ade irritating the app earan ce, m an n erism s, an d accent that had seem ed attractive in the sam e teacher beh av in g w arm ly. In stead of recognizing this nonobvious b u t actual causal relationship, they typically offered the m ore plausible causal hypothesis th a t th eir dislike of the attrib u tes had m ade them dislike the possessor of the attrib u tes.

E rroneous R eporting O f N on in flu en tial Factors

Subjects n o t only failed to rep o rt some influential factors, also they som etim es repo rted th at p articu lar factors had influenced their behavior w hen the experim ental evidence suggested they had had no such effects. T hese erroneous reports w ere found in several studies. E rroneous reports of the emotional impact of literary passages. In one ex p erim en t, subjects w ere asked to read a selection from the novel Rabbit Run by J o h n U pdike. T h e selection describes an alcoholic housewife who accidentally drow ns h er baby while b ath in g it. Even w hen read out of the context of the rest of the novel, the selection has a substantial em otional im pact on readers. Som e of the subjects read the selection as it had been w ritten, while others read a version w hich had one or both of two particu lar passages deleted. (It had been w rongly expected by the investigators that one of the two passages was central to the im pact of the selection as a w hole.) T h e resulting tw o-by-tw o design m ade it possible to assess the effect of inclusion or deletion of both passages on the subjects5 ratings of the em otional im pact of the selection. As it tu rn e d o u t, n eith er passage h ad any detectable influence on the rated im pact of the selection. W hen the subjects who had been exposed to the passages w ere asked ab o u t th eir effect on the im pact of the selection as a w hole, they insisted th at both passages had substantially influenced their reactions. For one of the passages, in fact, 86 percent of the subjects asserted th at the passage had increased the im pact of the selection. E rroneous reports about the effects of distraction on reaction to a film . Subjects in one study w ere asked to view a d o cu m en tary on the plight of the Jew ish poor in large cities. Som e subjects viewed the film while a d istractin g noise (produced by a pow er saw) occurred in the hall outside. O th e r subjects view ed the film while the focus was poorly adjusted on the proje cto r. C o n tro l subjects viewed the film w ith no distractions. A fter viewing the film , subjects rated it on three dim ensions— how interesting they thought it was, how m u ch they th ought o th er people w ould be affected by it, an d how sym pathetic they found the m ain ch aracter to be. T h e n , in the experim ental

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conditions, the experim enter apologized for the poor viewing conditions and asked subjects to indicate next to each ratin g w hether it h ad been influenced by the noise or poor focus. N either the noise nor the poor focus actually had any detectable effect on any of the three ratings. (R atin g s w ere in general trivially higher for distraction subjects.) In the only d em o n stratio n of reasonably good accuracy in subject rep o rt of stim ulus effects found by N isbett and W ilson, m ost of the subjects in the poor focus condition actually reported that the focus had not affected their ratings. A m ajority of subjects in the noise condition, how ever, erroneously rep o rted th at the noise h ad affected their ratings. Fifty-five percent of these subjects rep o rted that the noise had low ered at least one of their ratings. E rroneous reports about the effects of reassurance on willingness to take electric shocks. In a th ird study, subjects were asked to p redict how m uch shock they w ould take in an ex p erim en t on the effects of intense electric shocks. O n e version of the procedural protocol describing the experim ent included a ‘‘reassu ran ce’’ th at the shocks w ould do “ no p erm a n en t d a m a g e .” T he o ther version did not include this 1‘re a ssu ra n c e .” Subjects who had received the first version were asked if the phrase ab o u t p e rm a n e n t dam age had affected their predictions of the am o u n t of shock they w ould take, and subjects who had received the second version were asked if the phrase w ould have affected their predictions, had it been included. Inclusion of the phrase, in fact, had no effect on predicted shock taking, b u t a m ajority of subjects reported th at it did. O f those rep o rtin g an effect, m o re th an 80 p ercen t reported that the phrase had increased their predictions. Subjects who h ad not received the phrase were sim ilarly, an d erroneously, inclined to say th a t it would have increased their w illingness to take shock h ad it been included. T ak en together, the N isbett and W ilson studies show th a t, across a wide variety of behaviors and behavioral contexts, subjects’ reports of the causal influences on their behavior can be very inaccurate indeed. T h e findings cast considerable doubt on the correctness of sim ilar causal reports in daily life. M ore im portantly, the studies raise a question ab o u t the basis of such reports. H ow do subjects go about in venting (we use the term advisedly, since the subjects were certainly not detecting) causal explanations for behavior? It is to this question th at we next tu rn our attention.

TH E BASIS OF CAUSAL ACCOUNTS

For several of their studies, N isbett and W ilson used B ern’s technique of asking the sam e questions of observer subjects as were asked of the actual subjects themselves. Som etim es these observers w ere the subjects in control

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conditions who did not receive the critical m an ip u latio n s, and som etim es they w ere people who did not p articip ate in the experim ents at all b u t w ho simply read abbreviated protocols describing one or m ore experim ental conditions and then m ade predictions of how the real subjects would have responded. D ata from both types of observer subjects tell the sam e story: O bserver predictions w ere essentially identical to the causal reports of the actual subjects who had really been exposed to the experim ental setting an d the m anipulations. Such a finding for observers raises a central question: H ow im p o rtan t was the subjects’ own privileged access to the m ental events triggered by the m anipulations? If observers’ guesses were essentially the sam e as the subjects’ “ re p o rts ,” this would strongly suggest th at both evaluators had been based on som ething that was as readily available to observers as to subjects. N isbett and W ilson arg u ed th a t the “ so m eth in g ” obviously could not be a m em ory of the process by w hich the m an ip u latio n s influenced the behavior, since observers had no such m em ory. T h e observers could base their predictions only on their theories of the ways in which the p articu lar m anipulations would influence the particu lar responses. N isbett and W ilson argued that the basis of the actual subjects’ causal accounts was the sam e as their theories, shared w ith observers, of the ways in which the m anipulations w ould be expected to influence their responses. T h e only difference betw een observers and subjects is that observers knew that they were basing their predictions on their theories while subjects presum ably th o u g h t th at they were basing their accounts on th eir m em ories of m ental data. T his view of the origins of people’s causal accounts does n o t apply m erely to cases in which such accounts are inaccurate. It applies also to cases in w hich such accounts are accurate. Indeed, it allows us to predict precisely w hen such accounts will be accurate. T h ey will be accurate if, and only if, the theories ab o u t the behavior in question are also accurate. E m pirically, this m eans th at u n d e r m ost circum stances subjects will be right in th eir causal accounts if and only if observers, w orking w ith sim ilar externally available inform ation, also are right. People are, despite N isb ett’s and W ilson’s d em onstrations, often right in th eir accounts of the reasons for th eir behavior. A person who answ ers a telephone and asserts that he did so “ because it was rin g in g ” is surely right. A person who solves a problem by applying an ap p ro p riate algorithm and then asserts th a t he solved the problem by applying the algorithm , is right. A person w ho asserts th at he opened the refrig erato r door because he was h u n g ry is usually right. B ut we have theories ab o u t why we answ er telephones, how we solve problem s, an d why we open refrigerators, an d these theories are usually correct. Because these theories are so m anifestly correct, how ever, it w ould req u ire som e ingenuity to find cases in w hich the know ledgeable observer was not also correct.

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T h e notion that acto rs’ causal accounts are based prim arily on theories which they share w ith observers has strong im plications for the behavioral d o ‫־‬ m ains in w hich accuracy is to be expected. For those dom ains in w hich people have received explicit train in g in the use of an algorithm or ju d g m e n ta l strategy, then theories of process w ould be expected to be correct, and, therefore, causal accounts should be correct as well. T h u s, w hen stockbrokers are asked why they recom m ended the purchase of a given stock, they can easily report the algorithm they were using for stock reco m m en d atio n s an d can report how the features of the p articu lar stock m atch the features of the algorithm . T he same is tru e of clinicians w ho are train ed in the use of test‫־‬ score profiles to diagnose m ental illness. T h e clinician knows the stru ctu re of the algorithm he was taught and knows how the features of the profile correspond to the features of the algorithm . W e w ould expect reports of such ju d g m en ts to have at least some accuracy, an d they do (Slovic & L ichtenstein 1971). But there is every reason to assum e th at observers, who also are train ed in the use of the algorithm , w ould give equally accurate reports of the influences on the acto r’s ju d g m en t. S haring the theory, they should be able to duplicate the account. M any everyday life ju d g m en ts also are guided by “ alg o rith m s” of a sort. A ju d g m en t of an o th er p erso n ’s intelligence is one th a t we are all “ tra in e d ” to m ake, using certain sorts of d ata in certain ways and ig noring other sorts of data. For other social ju d g m en ts, how ever, we receive no special “ th eoretical” train in g and little if any feedback from others on the way we make the ju d g m en t. N isbett and Bellows (1977) studied the effects of a n u m b e r of factors on ju d g m en ts of the “ alg o rith m ” type versus ju d g m en ts for w hich people receive little training. T hese investigators asked a group of subjects to m ake a series of four ju d g m en ts of an applicant for a counseling position. Subjects rated their “ liking” for the applicant and assessed h er “ sy m p ath y ,” “ flex ib ility ,” and “ intelligence.” It was presum ed th a t only for the ju d g m e n t of intelligence would subjects explicitly follow an “ alg o rith m ” against w hich th eir ju d g m en ts could be self-consciously m onitored. Five stim ulus factors were m anipulated factorially. F o u r of these factors were the inclusion, or om ission, of p articu lar item s in the ap p lic a n t’s portfolio: (a) that she was unusually attractive, (b) th at she possessed superb academ ic credentials, (c) th at she had suffered a “ p ratfall” d u rin g h er jo b interview (spilling coffee on the interv iew er’s desk), (d) th at she had been the victim of a serious auto accident th at still caused h er considerable pain. T h e Fifth factor (e) was the r a te r’s expectation th at she w ould later m eet the applicant whose folder she had exam ined or w ould m eet some o th er applicant. Besides ratin g the applicant, the subjects were asked to assess how each of the five or fewer factors they were exposed to in their p articu lar experim ental

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condition had influenced th eir ratings of the applicant on each of the four dim ensions. A second group of subjects was never exposed to the portfolio or presented w ith any task of ratin g of jo b applicants. Instead, they sim ply were asked hypothetical questions ab o u t the im pact that the various factors (described to them only in b rief sum m aries) would have had on each of the ju d g m e n ts in question. F or exam ple, they were asked: “ Suppose you knew th at som eone was quite physically attractive. H ow w ould that influence how m uch you w ould like that p erso n ?” C om pariso n s of acto rs’ and o bservers’ causal assessm ents strongly supported the hypotheses: (1) that the acto rs’ reports and the observers’ predictions w ould be very sim ilar; (2) that the acto rs’ reports w ould be m ore accu rate for the “ alg o rith m -g u id ed ” ju d g m e n t of intelligence than for the other ju d g m en ts; and m ost im p o rtan tly , (3) th at the accuracy of the actors’ reports w ould not exceed the accuracy of the o b serv er’s predictions, for any of the ju d g m en ts. T h e acto rs’ m ean assessm ent of the influence of the various factors on their ratin g for a given dim ension and the o bservers’ m ean assessm ents of the influence of such factors correlated at consistently high levels (ran g in g from a “ low ” of 77. ‫־‬1‫ ־‬for the “ flexibility” ratin g to a high of + .99 for the “ intelligence” rating). T hese results suggest th at both g ro u p s’ causal assessm ents w ere produced in a sim ilar w ay, nam ely, by applying or g enerating sim ilar causal theories. At any rate, it is clear that the acto rs’ private access to their own m ental experiences did not cause their explanations to differ m uch from those that they could have pro d u ced on the basis of their theories alone. T h e m ore im p o rtan t results are the relative accuracy of the acto rs’ and the o bservers’ assessm ents and the specific functional relationships for which they w ere accurate or inaccurate. Figure 9.1 illustrates the basic finding: Actors, as a group, w ere “ a cc u rate” only to the extent that observers were sim ilarly accurate. In cases in w hich the observers’ general theories w ere app ro p riate (as in pred ictin g th at good academ ic credentials would lead them to infer high intelligence), the actors were quite accurate in rep o rtin g the influences on their own ju d g m en ts. In cases in which the observers’ predictions w ere inaccurate (for exam ple, in pred ictin g th at academ ic credentials would enhance liking or in failing to pred ict th at an expected m eeting w ould enhance ratings of the ap p lican ts’ sym pathy an d flexibility), acto rs’ reports w ere sim ilarly inaccurate. C o rrelatio n s betw een the acto rs’ reports of the effects of the various factors an d the actual effects of the factors were extrem ely high for the intelligence ju d g m e n t (794. = ‫ )־‬b u t essentially nil for the other ju d g m en ts ( 71 4 .+ ,31.— = ‫ ־‬and + .11, respectively, for “ lik in g ,” “ flexibility,” and “ sy m p ath y ” ). N o t surprisingly in view of the high correlations betw een the

Fig. 9.1 Effects of manipulated factors on judgments, subjects’ report about the effects of the factors, and observers’ predictions about the effects of the factors. From Nisbett and Bellows, 1977.

acto rs’ and the observers’ assessm ents, the correlation betw een the o b serv ers’ predictions and the actual effects on the actors w ere sim ilarly high for the “ intelligence” ratin g an d sim ilarly low for the o ther three ratings. T h e results provide no evidence th at actors m ade any use w hatever of their m em ories for the m ental events an d processes th a t pro d u ced th eir ju d g m en ts. Instead, like the observers, they ap p eared to rely on th eir theories about w hat factors influence the ju d g m en ts. T h e results also m ake it clear th at such theories range from highly accurate, in the case of factors influencing the intelligence ju d g m e n t, to totally in accurate, for all of the o th er ju d g m en ts. T h e N isbett and Bellows results are qu ite striking, b u t there are two caveats. T h e betw een-subject design of the study m ade it im possible to assess the accuracy of the individual subjects’ causal reports. It could be th at, 214

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despite the failure of subjects as a group to distinguish betw een effective and ineffective m an ip u latio n s, p articu la r subjects m ay have reported accurately the influences on th eir own ju d g m en ts. S m ith an d M iller (1978), in a critique of the study, seem ed to arg u e th at such accuracy did in fact occur. T h ey reanalyzed the N isbett an d Bellows d ata an d reported a p attern of low but significant correlations show ing th at those subjects who reported th at a given factor had raised th eir ratin g on a given dim ension tended to be those subjects whose ratin g on that dim ension was relatively high. S m ith ’s an d M iller’s conclusion th at the d ata provide evidence of introspectively accom plished accuracy is p rem atu re. Subjects who recognized th eir ratin g on a p articu lar dim ension to be relatively high m ay simply have been m ore likely to conclude th at they h ad been positively influenced by any specified factor present th an w ould subjects who gave low ratings on that dim ension. By the same token, any observer also w ould have been m ore likely to assert that a given factor X heig h ten ed ju d g m e n t y i n cases in which Y was relatively high than in cases in w hich Y was relatively low. N either actors nor observers in such cases w ould have m anifested any 44introspective aw areness” beyond th at in sim ply recognizing that th eir p articu lar ju d g m e n t was, in fact, relatively high or relatively low, for exam ple, that they liked the target a lot or d id n ’t particularly like her. It also should be noted th at very low or zero correlations betw een extrem ity of ju d g m e n t an d rated influence of various factors also w ould be nonprobative an d w ould not establish lack of introspective aw areness. If a particular subject gave high ratings on a p articu lar ju d g m e n t an d then asserted th at m ost or all of the p articu la r factors ab o u t which he was asked were noninfluential, he m ight be quite correct in those assertions. H is high ratin g m ight have been prod u ced by factors the exp erim en ter failed to list on the questionn aire. C o rrelatio n al analyses cannot settle m atters one way or the other. D espite the nonprobativeness of the d ata they m arshalled in support of th eir contention , Sm ith and M iller could still be right in th eir assertion that individual subjects m ight have been correct in th eir reports and that their accuracy was based on som e kind o f private access not available to observers. W e shall re tu rn to these possibilities later, in a general discussion of the question of acto rs’ accuracy. O u r second caveat about the N isbett an d Bellows results is that they cannot be taken as typical of the accuracy to be expected generally for reports of in terp erso n al ju d g m en ts. T h e investigators deliberately used im plausible, co u n terin tu itiv e effects suggested by previous research on interpersonal ju d g m ents, while taking no co rresp o n d in g pains to include representative, intuitively plausible effects. T h e investigators could have im proved the acto rs’ overall accuracy by including m ore effects, like the relationship betw een academ ic perfo rm an ce an d perceived intelligence, for which the objective d ata an d the acto rs’ theories w ere likely to correspond. It should be noted that

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there is no reason to assum e, how ever, th at such a strategy w ould have im* proved the acto rs’ accuracy relative to that of the observers.

TH E ACCURACY OF CAUSAL ACCOUNTS IN EVERYDAY LIFE

T his caveat retu rn s us to o u r chief concern: H ow accurate, in general, are our causal explanations in daily life? T h e re is a sense in w hich this question can never be answ ered. It even seem s, on the surface, like a question one ought not to ask, since no am o u n t of ex p erim en tatio n could ever indicate m ore than that such accounts are som etim es rig h t an d som etim es w rong. T h ere are, how ever, some useful things th at can be said ab o u t the question. First, it should be em phasized th at in all the research by N isbett, W ilson and their colleagues, the experim ental setting contained m an y plausible “ decoy” factors. Subjects were asked only ab o u t the effects of a few actually effective stim ulus factors and of a few plausible decoy factors. H a d subjects been asked about the influence of every conceivable factor— the presence of a dust m ote on the ceiling, the tenor of c u rre n t U .S . relations w ith C h in a , the effects of the subject’s breakfast eaten three days before— subject accuracy, at least in percentage term s, w ould rapidly have b egun to ap p ro ach 100 p ercen t. V iew ed from this perspective, o u r causal reports in everyday life are very accurate indeed: A lm ost all genuinely ineffective factors, of w hich there are infinitely m any, will be denied as having been influential. T his is not very encouraging, though, because the research to date makes it clear that it is child’s play to generate decoy factors th at people will falsely assert to have been influential and sim ilarly easy to m an ip u late genuinely influential stim uli that people will deny to have been influential. W e then have only to ask the question, “ Does everyday life often p resen t us w ith situations com parable to those in which N isb ett and W ilson placed th e ir subjects?” D ifferent readers will com e to different conclusions ab o u t this question. O u r own view is that the answ er is a resounding “ Y e s.” Life is fully as inventive as social psychologists are. W e hum a tu n e because we h eard a snatch of it on the radio a few m inutes ago and not necessarily because it has deep personal m ean in g for us. W e choose a sports jack et in p art because it was not the first one the salesperson pulled off the rack, an d n o t exclusively because of its style, fabric, an d fit. O u r overall affective reaction to a person influences, w ithout o u r know ledge, o u r evaluation of the in dividual attrib u tes of that person. W hen we are deeply affected by a book or a m ovie we sometim es will single out inconsequential factors as having co n trib u ted to its impact and som etim es will ignore consequential factors. (In d eed , a chief reason

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for read in g critics is to get a “ second opinion*’ ab o u t w hat factors influenced us and in w hat w ay.) T h is view of the accuracy o f o u r causal accounts has becom e controversial (see, for exam ple Sm ith & M iller 1978; Ericcson & Sim on 1978). T his is not the place to attem p t a reb u ttal of the criticism s of N isb ett’s and W ilso n ’s thesis, b u t it w ould be instructive to exam ine some of the m ajor criticism s to see w hether they cause us to doubt that people som etim es will be as inaccurate in their causal accounts in daily life as they have proved to be in the lab o rato ry . W e m ay group these criticism s u n d er four m ajor headings: (1) It is N isbett an d W ilson who are w rong in their causal accounts. T h ey focus on th e ir experim en tal m an ip u latio n s in asking th eir subjects about causal influences, b u t subjects focus, quite rightly, on the m ediating m ental events th at occur as a consequence of these m an ip u latio n s an d not on the m anipulations them selves. (2) N isbett and W ilson delayed in asking their subjects ab o u t th eir m en tal processes until m uch too late. H a d they used “ thinka lo u d ” techniques (Newell and S im on, 1972) or some other im m ediate probe, m uch m ore accuracy m ight have been found. (3) N isbett and W ilson used betw een-subject designs. H a d they used w ithin-subject designs, m uch m ore accuracy m ight have been found. (4) N isbett and W ilson exam ined relatively trivial behaviors. H a d they exam ined m atters of greater im port to the subjects, subjects w ould have been m ore accurate. W e will discuss each of these objections, particu larly as they concern the question of the accuracy to be expected of causal assessm ents in daily life.

M a n ip u lation s versus M ediators

U n d o u b ted ly N isb e tt’s and W ilso n’s m anipulations never directly caused any of the effects they exam ined. Instead, the m an ip u latio n s produced effects on the subjects, in the form of various m ental events, an d these m ental events in tu rn produced the behavioral effects. T h e m ost obvious exam ple is provided by the position effect study in w hich, it will be recalled, subjects failed to recognize the functional relationship betw een the left-to-right position of a g arm e n t and th eir own ratin g of th at g arm en t. P robably “ p o sition” had such an influence, at least in p art, because it d eterm in ed the ord er in which the various item s w ere exam ined. O rd e r of ex am in atio n , in tu rn , m ay have influenced a score of factors an d processes, including the am o u n t of tim e spent ex am in in g each item , various sensory thresholds, and perhaps the subjects’ decision criteria an d ju d g m e n t rules. T h u s, the subjects’ reports (for exam ple, I liked item 4 because it “ felt softest” or “ seem ed m ost carefully constru c te d ” ) m ay actually be accurate. W hat such a subject is not recognizing is

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the role that the ex p erim en ter's m an ip u latio n had played far earlier in the causal chain (for instance, the influence of “ p o sitio n " on “ ex am in atio n tim e ," which influenced “ thresholds, associations, and decision c rite ria ," which ultim ately influenced subjective experience of “ softness" or “ care in co n stru ctio n "). T h u s the subjects m ay indeed have had introspective access to im portant m ediating events, that is to the last “ lin k s" in the causal chain. A ssum ing such introspective access (and rem em b er it is only an assum ption and not a dem onstrated fact), how accurate o r discerning has the subject been? T h ere is no satisfactory answ er, unless we have a prio r notion o f w hich links in the causal chain we deem a “ fair te st" of the subjects' access. W hen J o h n says he m arried J a n e in p art because he thinks she is “ u n d e rs ta n d in g " and “ b ea u tifu l," shall we challenge his assertion by po in tin g out that he thinks she is u n d erstan d in g because he has gotten to know h er well and th at if she h a d n 't lived next door he w o u ld n 't have gotten to know h er well? Shall we say that he “ really " m arried h er because of spatial p roxim ity, (F estinger, Schachter, & Back 1950)? Shall we point out that p u re sexual passion has strongly influenced his perceptions o f h er beauty, ju st as previous sexual deprivation initially influenced his subjective experience of being sexually attracted to her? T h e point should be clear. Every causal sequence is extrem ely com plex— one m ight say that is is infinitely com plex— and it w ould be extrem ely difficult to dem onstrate that som eone is totally accurate or totally inaccurate about such a sequence. T h e p rop er question for o u r concerns is this: Is the actor aw are that p articu lar responses are functionally related to particular stim uli or situational factors, how ever m any or com plex the links? T h o u g h we cannot prove that an acto r's own causal report is w ro n g — if by “ w ro n g " we m ean that the antecedent sentim ent, idea, tho u g h t, o r w hatever did not occur — we can, how ever, prove that by n o rm al stan d ard s o f discourse, his causal analysis is in ad eq u ate or incom plete. T h a t is, a subject can be shown to ignore o r deny the influence of some factor th a t was necessary to produce his response in a given situation. If the e rro r involves functional relationships about w hich no one has ever claim ed introspective insight— for exam ple, the relation betw een the stru ctu re of a m olecule of liquid and subjective experience of taste— then the d em o n strated failure of introspection is trivial. But if the “ e rro r" involves a com m on functional relationship, typical of the sorts of “ cau ses" and “ effects" ab o u t w hich we assum e ourselves to be know ledgeable, then the d em o n stratio n is far from trivial. Such errors will lead us to say and do unw ise things about poten tial changes in o u r env iro n m en t. T h e possibility that we are not entirely w rong w hen we deny the direct influence, on o u r ju d g m en ts, o f position, o rd e r of presentation, proxim ity, contrast, or general evaluation of the object, is cold com fort. If such factors do influence o u r behavior, albeit th ro u g h a highly

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m ediated causal chain, we are likely to get into trouble if we believe they do not; even if there is some sense in which o u r claim is logically defensible.

R etrospective versus C oncurrent Accounts

As N isbett an d W ilson them selves acknow ledged, the closer the tim e of a causal in q u iry is to the actual occurrence of the m ental process, the m ore likely it is that the causal account will be accurate. T his should be tru e, if for no o ther reason, because m em ory of genuinely influential events m ay decay over tim e, especially o f any events not tran sferred from short-term to longte rm m em ory. It should be clear, how ever, th at a report about m ental events is not the sam e th ing as a rep o rt ab o u t m ental processes, even u n d er the lim iting tem poral case of “ th in k -alo u d ” procedures. Access to process is not a m a tte r of m illiseconds b u t of definitions. By the definition we prefer, there can be no such th ing as direct observation o f m ental processes, any m ore th an there can be direct observation o f physical processes. In both cases, it is only events th a t are observed. Beliefs about process—beliefs about the way in w hich one event influenced an o th er— are always the product of inference and not of direct observation. F rom the stan d p o in t of o u r central concern w ith the accuracy to be expected in everyday life, it is clear that the tem poral criticism of N isb ett’s and W ilso n ’s thesis scarcely is applicable. T h e ir subjects were typically asked ab o u t the causes o f th eir b eh av io r im m ediately after it occurred an d never m o re th an a few m inutes after. T h u s the accuracy th at they found can be reg ard ed as som ething close to the m ax im u m th a t w ould norm ally be obtain ed for com parable behaviors in daily life. W hatev er the m erits of the ternporal a rg u m e n t for theoretical issues concerning access, the arg u m en t cannot be used to supp o rt the view th at causal accounts in daily life generally would be expected to be m ore accurate th an those in the laboratory.

B etw een versus W ith in D esigns

A lm ost all of the N isbett an d W ilson studies used a betw een design. T his allow ed the exp erim en ters to determ in e w hether, overall, a given m anipulated factor had an effect, w hich in tu rn allowed them to assess w hether the subjects in a p articu lar experim ental condition w ere, overall, accurate in their assertions or denials of the influence of a factor to w hich they were exposed. T w o criticism s can be aim ed at this strategy. T h e first is th at such a design can never reveal w hether an individual subject was accurate or not. E ven if there w ere individual differences in accuracy, these w ould be of interest only if it could be shown th at they were system atic. Even then it w ould

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n o t affect either the conclusions ab o u t accuracy for subjects in general, or the contention that such accuracy as exists is based on the accuracy of su b jects’ theories. A second criticism of the betw een design is th a t subjects w ere being denied inform ation th a t w ould have been p ertin en t to causal accounts. T h is is perfectly true, b u t exactly w hat in form ation w ere they being denied? T h e m ost obvious answ er is th at the subject was denied know ledge of w hat his response w ould have been had he also p articip ated in one or m ore of the o th er experim ental conditions. If the response were different an d all factors b u t one w ere held constant, then this w ould surely have been enorm ously helpful to the subject in detecting the causal role of the m an ip u lated factor. B ut w ould we w ant to say th a t such a helpful h in t cam e from introspection? A ny observer could reach the sam e conclusion as the actor did, by sim ply a ttrib u ting the behavior to th a t distinctive factor w ith w hich it was observed to covary. It is actually the betw een design th at m axim izes the potential advantage of the actor over any observer, because it leaves the ac to r’s p riv ate introspective advantages intact. T h e w ithin design m akes public m ost of the additional clues it provides. M ore im portantly, from the stan d p o in t of o u r m ain concern, the question to ask is w hether it is the betw een design or the w ithin design th a t com es closer to cap tu rin g the essence of everyday life ju d g m en ts. W e w ould arg u e that it is clearly the betw een design w hich comes closer. W e know a w arm Belgian psychology in structor or a cold Belgian psychology in stru cto r, n o t two physically identical Belgian psychology instructors, one of w hom is w arm and one of w hom is cold. W e read literary selections as they are w ritten , n o t once w ith a particu lar passage included an d once w ith the passage deleted. W e select a sports jack et after seeing a series of sports jack ets in the o rd er A B C D and not after seeing them in the o rd er D B A C on T u esd ay , B C D A on W ednesday, an d so on. A stockbroker recom m ends IB M over o th er stocks w hich differ on a dozen dim ensions from IB M , n o t IB M over an o th er stock identical to IB M in all respects save one. A m an never steps into the sam e stream twice, and life itself has a betw een design.

Im portant versus T rivial B ehaviors

T he claim can be m ade th a t for life’s m ost im p o rtan t ju d g m e n ts, m atters are quite different from w hat they are for the relatively in co n sequential m atters exam ined by N isbett an d W ilson. For an im p o rta n t decision, we m ay m ull over the alternatives in a highly conscious, ru m in ativ e w ay, com pare alternatives feature by feature, an d so forth. W e are sym pathetic to this view (though we should note th a t others, p articularly those holding a psychodynamic view, generally argue th a t m atters are the opposite, an d it is often life’s

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m ost im p o rtan t decisions ab o u t which we are likely to be deluded). It does seem likely to us th at, oth er things being equal, the m ore im p o rtan t a ju d g m ent is, the m ore likely we are to engage in cognitive processes th at are sufficiently explicit and articu lated to provide b etter than average clues ab o u t w hich factors are m ost im p o rtan t to the ju d g m en t. T h e arg u m en t is at m ost a q u an titativ e one, how ever, an d we can envision no m echanism by which importance alone could do m ore th a n am plify the “ signal’’ com ing from the influential factors and d am p en the “ n o ise” com ing from the noninfluential ones. T h e question is an em pirical one. F o rtu n ately , we are able to report a p articularly relevant study w hich speaks both to the question of accuracy in very im p o rta n t ju d g m e n ts an d to the question of accuracy w hen a w ithin design is used. W eiss and B row n (1977) studied the accuracy w ith which w om en subjects could identify influences on th eir m ood states. T h e ir procedure was quite sim ple. T h ey asked their subjects to report each day for a tw o-m onth period the quality o f their m oods th a t day, an d to keep track o f several factors that m ight potentially influence m ood state. T hese included am o u n t of sleep the night before, the w eather, general state of health, sexual activity, stage of the m en stru al cycle, an d the day of the week. A t the end of the d ata-g ath erin g period, the p articipants Filled o u t a Final set of item s asking them ab o u t their perceptions of the relative im pact on their m ood of the factors they had m o n ito red daily for two m onths. In o rd er to derive co rrespo n d in g “ objective” w eights for each of these factors, the investigators perfo rm ed m ultiple regression analyses on the m ood score for each subject. As the read er pro b ab ly can foresee, there is no totally satisfactory w ay of assessing the relative co n trib u tio n s of each antecedent or “ predictor v aria b le” to the outcom e variable (th at is, “ good m o o d ” score). N evertheless, the investigators were able to derive values th at could be interp reted as indicators of the p ercent of total variance in m ood explained by each p red icto r variable (w ith som e, b u t not totally ad eq u ate, control for the other p red icto r variables). T h ese values then could be treated as “ objective w eights” for the correlates of each su b ject’s m ood w hich, in tu rn , could be co m p ared w ith the subjective w eights the particip an ts h ad reported in the follow-up q uestio n n aires. T h ere w ere great discrepancies betw een the objective w eights, determ in ed by m ultiple regression analysis for the entire gro u p of subjects, and the average subjective w eights rep o rted by the subjects. F or instance, objectively, “ day o f the w eek” accounted for a substantial p ro p o rtio n of the variance in subjects’ rep o rt of m ood, while “ am o u n t of sleep” tended to be a rath er poor pred icto r. Subjectively, “ sleep” was rated on the average as the single m ost im p o rta n t factor, while day o f the week was rated as relatively u n im p o rtan t. In d eed , overall, the correlation betw een the objective weights and the subjective w eights was slightly negative!

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T h e finding of no accuracy in the g roup d ata is sim ilar to the accuracy levels found by N isbett an d W ilson on the basis of th eir sim ple betw eensubject designs. B ut the special feature of the W eiss and B row n w ithin-design study is the opp o rtu n ity it provided to look m ore closely at the self-insight revealed by individual subjects. It was possible to exam ine the co rrelation betw een subjective and objective weights for each individual and th ereb y determ ine w hether the p articipants whose m oods objectively covaried m ost w ith a particular factor also were those whose subjective reports retrospectively gave that factor the greatest weight. T hese correlational analyses revealed little if any evidence of insight into the correlates of em otional fluctuations. F our of the six correlations yielded positive, b u t far from statistically significant, correlatio n s— ran g in g from a high of + .127 and + .108 (for “ stage of the m en stru al cycle” an d “ o rg a s m ,” respectively) to a low of + .04 an d + .01) (for “ h ea lth ” an d “ sleep ,” respectively). T w o of the six factors (th at is, “ day of the w eek ” an d the “ w eath er” ), on the other h an d , yielded negative correlations an d by conventional statistical criteria significantly so. T h a t is, the m ore the su b ject’s m ood covaried w ith day of the week or w eather, the less likely she was to give w eight to these factors in her retrospective report. T h u s subjects erred in assessing the im pact of various d eterm in an ts of th eir m ood fluctuations, m istak in g strong influences for w eak ones o r vice versa, an d even failing to d istinguish betw een positive influences and negative ones. If subjects’ im pressions o f the correlates o f th eir m oods do not reflect objective experience, then w hat do they reflect? T h e read er by now will be q uite prep ared for the answ er. W eiss an d B row n conducted a follow-up study in w hich they sim ply asked a g roup of u n d erg rad u ates to fill out a short questionnaire on m ood d eterm in an ts. T h e questio n n aire asked them to consider the case of an alleged p articip an t in a psychological study of m ood fluctuation and to estim ate w hat im pact w ould be exerted on the p a rtic ip a n t’s daily m ood by various factors, th at is, w eather, sexual activity, d ay of the week, an d so on. T h e relative w eightings predicted by these “ o b serv ers” w ere v irtually identical to those reported by the participants. In fact, the only difference in the ord erin g of the m ood d eterm in an ts was in “ w eath e r” an d “ d ay of the w eek.” T h e participants ran k ed them th ird and fourth respectively, while the “ observers” ran k ed them fourth an d th ird respectively, a result th at m ade the observers slightly m ore “ ac c u ra te ” th an the particip an ts them selves were. T h e im plications of such d ata seem obvious. P a rtic ip a n ts’ daily experience o f em otional ups and dow ns an d th eir concom itants even the daily recording of these events— gave them no advantage in estim atin g the correlates of their moods. In a sense, these data seem inevitable given p eo p le’s covariation detection capacities. T h a t is, w eak objective covariations are difficult, if not im possible, to detect in the absence of a previous theory, an d illusory correlations reflecting o n e ’s theoretical biases are q uite ap t to be falsely

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“ d e te c te d .” T h e only new thing in the present data is the d em onstration that any access to private m ental events and processes that the actor might enjoy provides no prophylaxis against such errors. F rom a practical standpoint, how ever, the d ata go far beyond this. T hey suggest that people’s guesses about causality for the very most im portant outcom es are as faulty as their guesses about inconsequential outcom es. Simply put, they suggest that people do not know w hat m akes them happy an d w hat m akes them un h ap p y . T h e W eiss and B row n study thus addressed three questions that could be fairly directed tow ard the N isbett and W ilson studies. (1) Does im portance of the ju d g m e n t g u aran tee accuracy? (2) Does a w ithin design, in which subjects are exposed to m any levels of the same factor, g u aran tee accuracy? (3) Does individual assessm ent, as opposed to the assessm ent of group m eans, allow us to d em onstrate accuracy? T h e answ er to all three questions w ould appear to be no. W e tu rn , finally, to a question left u nansw ered in the studies by N isbett an d W ilson and by W eiss an d Brown: W hen do the a cto r’s introspective insights lead him to be m ore accurate than the observer?

AC TO RS’ U N IQ U E SOURCES OF IN SIG H T AND ERROR

W e have argued strenuously that acto rs’ insights into the causes of their behavior are best reg ard ed as inferences rath er than as privileged or “ d irec t” observations of the w orkings of their m ental m achinery. We do not deny that actors m ay know a great deal that observers do not know and that m uch of this know ledge is directly relevant to the accuracy of their causal analysis. A lthough a full treatm en t o f this topic w ould take us far afield an d expand an already long ch ap ter beyond reasonable lim its, we can sum m arize some of these “ u n iq u e ” sources of know ledge. 1. Let us begin by noting the obvious. M an y stim uli and also m any responses are to a degree am biguous, that is, they m ay mean different things to different people. T h e actor often enjoys u n iq u e know ledge of the m eaning he attaches to a stim ulus or to his own behavior. M oreover, as the generation o f gestalt social psychologists were quick to em phasize, such subjective accounts o f stim uli an d responses often m ay be crucial to u n d erstan d in g and exp laining the acto rs’ behavior. T h e observer, or the scientist who m anipulates the objective features of the acto rs’ en v iro n m en t, m ay sim ply lack the necessary insights about how the relevant stim uli or responses as they are perceived or in terp reted by the actor. T h e actor w ho nam es his firstborn “J a s o n ,” or chokes up w hen he hears

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Smoke Gets in Your Eyes, or writes a check to the A m erican C an ce r Society, knows a great deal ab o u t the idiosyncratic m eanings or associations relev an t to his behavior. Som etim es this idiosyncratic know ledge arises sim ply because the actor recalls the past experiences that plausibly dictate the p resen t m eaning of p articu lar stim uli or responses; som etim es it arises because he consciously experiences a p articu lar chain of thoughts or associations. W e do not im ply that the actor always has special insight into m ean in g or full access to associative netw orks, only th at he sometimes has such insight o r access an d th a t w hen he does he enjoys a potential advantage in causal analysis. 2. In m any contexts the ac to r’s u n iq u e know ledge m ay concern not the p articu lar stim ulus or response b u t know ledge of his ow n history an d fu tu re goals. T h a t is, he m ay know a great deal ab o u t his tastes, his priorities, his m otives, his aspiration level, his self-regulation strategies, an d som etim es even his decision criteria or w eighting functions (see Slovic’s and L ichtenstein ’s 1971 review). J o h n m ay know that he is try in g to save m oney for a ski w eekend in C olorado o r th at he cares a lot ab o u t good service and does not m ind having to drive a long way to reach a restau ran t. J a n e m ay know th a t she has prom ised herself to lose tw enty pounds before next C h ristm as or to stop pestering h er secretary ab o u t small m atters. A gain, in each case such knowledge is potentially relevant in helping the actor to u n d erstan d his or h er otherw ise surprising actions in a variety of everyday situations. 3. Finally, the actor often has m uch know ledge of his past b eh av io r in a variety of circum stances. T his know ledge m ay provide a m ark ed inferential advantage. If J a n e know s she accepted J o h n ’s d in n e r in v itatio n b u t not G eo rg e’s and knows th at both suitors proposed very sim ilar d in n e r an d afterd in n e r plans, she is at a m ark ed advantage in assigning p ro p er causal w eight to suitor versus proposal (at least in com parison to eith er G eorge or J o h n , who m ay be ig n o ran t of each o th e r’s fate). M ore generally, the actor often enjoys advantages over the observer by virtue of know ing in fo rm atio n p ertin en t to K elley’s (1967) A N O V A variables of consistency o r distinctiveness. W e m ay sum m arize all three sorts of advantages enjoyed by actors by saying that the intuitive scientist’s task in causal analysis is akin to th a t of a detective, and, in th a t role, the actor enjoys privileged access to m any “ clu es.” T h e actor can, how ever, largely forfeit this ad vantage by sim ply sharing his know ledge or “ clues” w ith the o bserver— th a t is, by telling the observer w hat the stim ulus m eans to him , w hat his aspirations and priorities are, o r how he responded in previous situations that share certain co m m o n o r distinctive features w ith the one u n d er consideration, an d so forth. In such cases, we argue once again th a t the a cto r’s an d the o b serv er’s causal assessm ents will be sim ilar. W e should hasten to add th at an ab u n d an c e of clues is only som etim es advantageous to the detective, an d , by the sam e token, the actor s additional know ledge— of associations, priorities, p ast ex­

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periences, an d the like— is only som etim es an advantage in causal analysis. M ore specifically, the a c to r’s u n iq u e know ledge is disadvantageous in m any circum stances that the read e r should now be able to predict on the basis of previous chapters. If the ac to r’s causal theories ab o u t the relevance or im pact of p articu la r stim ulus m eanings are incorrect, then possession of privileged inform ation ab o u t such associations or connotations can be disadvantageous. If a new p a re n t’s preference in nam es for a new born child is determ in ed by sim ple fam iliarity (Z ajonc, 1968) then access to a rich associative netw ork m ay place the p a re n t at a d isadvantage to those observers whose only clue is the know ledge th at “ the nam e ‘J a s o n ’ seems a pretty po p u lar choice for p aren ts a ro u n d here in the last few y e a rs .” T h e a c to r’s u n iq u e access to additional cues o r inform ation also m ay prove to be m ore an inferential draw back than an asset if the antecedents of w hich he is uniquely aw are are m ore salient than they are causally influential. T h e m iddle-aged m an w ho becom es involved in an affair w ith a y o u n g er w om an m ay be well aw are of the popularly accepted theories of such liaisons. H e even m ay be w illing to apply such causal theories (for exam ple, “ male m e n o p a u se ,” “ the search for reassurance concerning o n e ’s sex u ality ,” “ fear of the ap p ro ach in g loss of y o u th ,” “ com pensation-seeking upon recognizing th a t o n e ’s greatest am b itio n s are o u t of re a c h ” ) to other people who have engaged in sim ilar relationships. B ut w hen ex p laining his own actions, the acto r is ap t to rhapsodize ab o u t a new ly appreciated ability to smell flowers, ab o u t the sudden discovery of an “ in n er self,” or about the welcom e u p ro a r of long-quiescent viscera. As a result, the acto r will insist th at he alone “ u n d e rsta n d s” his actions an d that his case is u n iq u e in its determ in an ts, w hile his friends w ho do not share his access to private thoughts and feelings shake th eir heads at his “ self-delusions.” In short, the a c to r’s u n iq u e ability to introspect will aid the goal of selfinsight only to the extent that the products of such introspection are roughly as causally relevant as they are available an d vivid, an d only to the extent that they reflect accurate theories o f why people like him self, o r people in general, behave as they do. W hen will the a c to r’s causal accounts be m ore accurate than the o b serv er’s? T h e answ er is straightforw ard en o u g h in the abstract: W hen the a c to r’s d ata an d theories are superior, he will be m ore accurate, w hen either is inferior he m ay be less accu rate. W ho is m ore often correct? U nd o u b ted ly it is the actor, since he norm ally possesses m ore com plete d ata. B ut, as we hope we have m ade clear, the data are far less im p o rtan t to the generation of causal accounts th a n the lay scientist is w ont to p resu m e, an d su p erio r access to d ata is in any case a tw o-edged sw ord. A corollary is that, on those occasions w hen the observer possesses a su p erio r theory, it is norm ally the observer w ho has the ad vantage.

SELF-KNOW LEDGE AND SEL F-IM PR O V E M E N T

W e should close by po in tin g out the relevance of this ch ap ter to the larg er concerns of the book. W e have claim ed th at peo p le’s inferences ab o u t the w orld are m ade u sing strategies th at are often less than optim al, and som etim es woefully inad eq u ate. W e know from previous experience th a t some people are inclined to criticize o u r arg u m en ts on the g rounds of introspection: “ W ell, I know I d o n ’t th in k th a t w a y .” It should be clear th a t this chapter m ay be regarded as an extended reply to such a critic. T h e critic’s introspections are not the court o f last resort. T h ey provide clues only, and clues th at m ay be m isleading, as to the w orkings o f o u r m inds. T h u s a m em ber of a grad u ate adm issions com m ittee m ay assert th at he is m ak in g decisions by using a rough m ental equivalent of a regression form ula h av in g factors A, By C, and D w ith approxim ate w eights 4, 3, 2, an d 1. H e m ay flatly deny that he ever engages in “ persona m a tch in g ” or is subject to co n trast effects or to halo effects. W e are saying th at his assertions and denials should be treated as, at best, plausible hypotheses th at are subject to co n tradiction by data. (T he read er who wishes to d em u r from this conclusion w ould be advised to read Slovic’s and L ich ten stein ’s 1971 review of the degree of correspondence th at is to be expected betw een expert ju d g e s ’ assertions ab o u t the weights they apply to various factors in m aking professional decisions and the weights they can be shown em pirically to em ploy.) A still m ore im p o rtan t im plication of this ch ap ter is th a t o u r claim s of the limits of introspection suggest a very serious roadblock on the p ath to inferential self-im provem ent. If our cognitive processes w ere tra n sp a re n t to us, then it w ould be easy to replace less optim al inferential strategies w ith su p erio r ones. B ut if, as we have claim ed, the n atu re of o u r cognitive processes can only be know n to us only th ro u g h the use of inferential strategies p ro n e to the sam e sources of bias and e rro r as those we wish to exam ine, then the learn in g of superior strategies necessarily m ust be seriously im peded. W e discuss this question at m ore length in chap ter 12.

SUM M ARY

O u r ability to know ourselves is m ore lim ited and m ore subject to e rro r th an com m on-sense beliefs w ould suggest. P eople’s characterizations of th e ir own dispositions, th ough difficult to assess objectively, clearly reflect a heavy reliance on theories ab o u t them selves. Self-characterizations often seem to persist despite co n trad icto ry data. 226

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K now ledge of o n e ’s own em otions an d attitudes, though com m only believed by the layperson (an d m any philosophers) to be “ d irec t” and certain , has been show n to be indirect and prone to serious error. Such know ledge is based in large p art on inferences ab o u t the causes of behavior. F re q u e n t errors in the self-ascription of em otions and attitudes would appear to be inevitable, given the inadequacy and inaccuracy endem ic to causal exp lanations o f o n e ’s ow n behavior. P eople’s causal accounts explaining th eir ow n b ehavior have been shown in a wide variety o f settings to be: (1) often em pirically w rong, (2) little differen t from the accounts o f observers w orking from im poverished inform ation and w ithout benefit of the introspective clues available to the actor, an d (3) based m ore heavily on causal theories than on the observation of m ental events. W h eth er m ost causal accounts in daily life are as prone to erro r, are as sim ilar to those of m inim ally inform ed observers, an d are as heavily dictated by theory as those exam ined in the lab o rato ry , is unknow n an d perhaps unknow able. P erh ap s the m ost th a t can be said w ith confidence is th at a h ig h er fraction of such daily life accounts m ay be characterized by these qualities than com m on sense w ould suggest or th an would be congenial to o n e ’s sense of security an d control.

10 psychodynamics versus psychologic

The mind is always the dupe of the heart. La Rochefoucauld

Every erroneous inference, though originating in moral causes, involves the intellectual operation of admitting insufficient evidence as sufficient. John Stuart Mill

Like L a R ochefoucauld, we believe that m any inferential errors an d acts of folly can be traced to m otivational or em otional causes, though the connections m ay be subtler than m ost laypeople and m any social scientists seem to recognize. But the claim that it is always, or even usually, the passions that lead the m ind astray seems to us to go m uch too far. O ften, the sources of inferential erro r are prim arily cognitive or inform ational. A nd, as M ill asserts, “ m o ral” causes of inferential e rro r— that is, causes involving wishes, values, or m otives— are never sufficient; they req u ire the collusion of intellectual shortcom ings in the acquisition or evaluation of evidence.

H O T V S. C O L D C O G N IT IO N : AN H IS T O R IC A L P E R S P E C T IV E T h e preceding chapters presented substantial evidence of im perfect rationality in h u m an ju d g m e n t and behavior. But the observation that people, even highly intelligent people, can think and act irrationally is scarcely new. 228

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T h e distinctiveness of the present perspective lies prim arily in the relative w eight placed on “ intellectu al” or inform ational causes of irrationality, as opposed to m otivational ones. R obyn D aw es (1976), in an essay th at has greatly influenced the present ch apter, pointed out th at psychologists from A ristotle to F reud conceived of personality as b ein g o rganized hierarchically. T h o u g h differing as to the n u m b e r and precise n atu re of the various levels of personality, m ost thinkers classified the intellectual functions as som ehow “ h ig h e r” than em otional or m otivational ones. Personally or socially destructive behaviors then are reg ard ed as the result of “ in tru sio n s” of the “ low er” functions into the proper province of the higher ones. T h e “ in tru sio n ” view of h u m a n folly is parsim onious only to the extent that n orm al or unim passioned intellectual functioning is held to approach perfect rationality . M u ch of this book has questioned the facility w ith which people m anage the purely intellectual tasks of collecting an d analyzing evidence. G iven these shortcom ings, the rule of parsim ony would seem to req u ire th at we hesitate before p o stulating additional, extra-intellectual agencies in accounting for ju d g m e n ta l failures in those cases w here the errors seem to be co n g ru en t w ith the p erso n ’s needs or values. W e have no wish to deny that people’s needs and m otives are im p o rtan t to personal and social dysfunctions. B ut, like m any contem porary psychologists, we believe th a t m otivational constructs have been too readily an d indiscrim inately invoked to explain failings th at are at the least im portantly aided, and p erhaps even largely d eterm in ed , by cognitive shortcom ings. Such debasem ent of the coinage of m otivational constructs, we feel, has lim ited o u r u n d erstan d in g o f both m otivational and cognitive processes and u n d erm in ed o u r ap p reciatio n of the often subtle interactions betw een these processes. T h e recent intellectual history of the contest betw een m otivational and nonm otivational approaches is instructive. Both of the m ajo r “ schools” in early tw entieth -cen tu ry psychology— psychoanalytic and behaviorist— featu red p rim arily m otivational theories. B ehavior, as L eventhal (1970) pointed out, was seen by both schools to be the p roduct of m otivational forces, instincts, need states or drives. From this perspective, everything the organism does can be seen as in stru m en tal. All behaviors, not only overt actions b u t also perceptual and cognitive responses, are the potential h andm aidens of need states. T h is “ m otivational im p erialism ” was challenged early on by T o lm an , who m a in tain ed th a t some responses, notably learn in g responses, take place in the absence of any pressing biological drive state. T h e ensuing battle g en erated m ore h eat th an light, an d m ost psychologists reg ard the question of “ u n m o tiv ated le a rn in g ” as unresolved an d p erhaps unresolvable. T h e next b attleg ro u n d was the “ N ew L o o k ” enterprise in the field of perception following W orld W a r II. T h e N ew Look pro p o n en ts were confid en t th at perceptions could be shown to be influenced massively by needs,

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wishes, values, fears, and o th er m otivational factors. P o o r people w ould perceive coins as larger than rich people w ould, because of the g reater value of coins to the poor. H u n g ry people w ould see food in tachistoscopically presented stim uli (or som etim es “ d efen d ” against seeing food), w hereas satiated people w ould not. E g o -th reaten in g stim uli w ould be perceived less readily than n o n th reaten in g stim uli w ould, an d so forth. A lthough the initial d em onstrations of such p h en o m en a seem ed prom ising, m any theorists were quick to co u n ter w ith n o n m o tiv atio n al in terp retations of the sam e phenom ena. T w o arg u m en ts consistently w ere em phasized in these counterattacks (cf. Erdelyi 1974). O n e arg u m e n t p u rsu ed the distinetion betw een m otivational influences on overt reports an d parallel influences on covert perceptions o r private experiences. P ro p o n en ts of the n o n d y n am ic view refused to accept overt verbal reports as evidence of tru e covert perceptions. T h e other arg u m en t em phasized th at experience, fam iliarity, an d o th e r purely “ inform atio n al” factors could account for the sam e findings th at h ad been cited initially as evidence of m otivational influences. H ig h e r “ perceptual thresholds” for obscene w ords, for exam ple, w ere in terp reted as reflecting m erely the low er frequency with which such w ords ap p eared in p rin t an d hence their lower fam iliarity an d p o o rer discrim inability. T h e critics of the N ew Look research first seem ed to carry the day, as the im pact of m otivational factors on perceptions generally proved to be slight and unreliable (once potentially co n tam in atin g n o n m o tiv atio n al artifacts w ere rem oved o r controlled), with large effects confined alm ost exclusively to perceptions of highly im poverished or highly am biguous stim uli. M o re recen t reviewers (for exam ple, Erdelyi 1974) questioned th at early verdict, an d a new generation of investigators relying on new an d m ore sophisticated techniques has revived the debate. It rem ains to be seen w h eth er persuasive evidence for the N ew Look p h en o m en a will be found for m otive states th a t are less th a n intense o r for stim uli th at are of low am biguity. T h e m ost recent aren a for the debate over the in tru sio n of m otives into higher o rd er processes has been in social psychology. In the aren a of attitu d e change, M cG uire (1960) co n trib u ted one dem o n stratio n exp erim en t th at was highly prom ising for the m otivational “ in tru sio n ” view. M cG u ire show ed that change in a given belief (the “ m in o r p rem ise” in a logical syllogism) is heightened w hen that belief is logically connected to a conclusion th at the subject deem s desirable, and is a tten u ated w hen it is logically connected to a conelusion that the subject deem s undesirable. U n fo rtu n ately , w ith very few exceptions (for exam ple, D illehay, Insko, an d S m ith 1966), n e ith e r this elegant dem onstration n o r the m ore general issues it raises have been followed u p by subsequent investigators. It has been in con tem p o rary attrib u tio n theory that the in teractio n betw een m otivational an d intellectual processes has been m ost vigorously p u rsued. T h o u g h H eid er was the fo u n d er of the highly cognitive research are a of

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causal a ttrib u tio n , he him self was a pro p o n en t of the ‘‘in tru sio n ” view. In fact, he gave precedence to m otivational over cognitive considerations in his statem en t of the criteria for selection of a causal attrib u tio n : “ (1) the reason has to fit the wishes of the person, and (2) the d atu m has to be plausibly derived from the reaso n ” (1958, p. 172). T h e second of H e id e r’s criteria has been docum ented repeatedly by num erous attrib u tio n researchers, including Jo n e s and Davis (1965), Kelley (1967, 1972a), W einer (1974), and M cA rth u r (1972, 1976). T he first criterion of ‘ ‘w ish-fulfillm ent’ ’ has suffered a different fate. It has received very m ixed em pirical support, and, perhaps inevitably in view of the history we have outlined, the contest betw een the m otivational and nonm otivational interpretations of research findings has been far m ore spirited than conclusive. In social psychology, the debate has been called one betw een proponents of “ h o t” versus “ cold” cognition or betw een “ psychodynam ics” versus “ psychologic” (A belson, 1968). W e would digress too far to review all of the evidence on the most recent version of this controversy. W e will sketch two illustrative dom ains in which the controversy cu rrently is raging: a debate over the existence of self-serving or ego-defensive biases in the attrib u tio n process, and a sim ilar debate over the m otivational versus nonm otivational basis for racial and ethnic prejudice.

SE L F-SE R V IN G BIASES IN CAUSAL A T TR IB U T IO N S

T h ere are few beliefs m ore deeply ingrained in the perspectives of both laypeople and professionals th an the notion that people tend to explain the causes of their own behavior, to them selves as well as to others, in a selfserving m anner. People are presum ed to be m ightily inclined to attrib u te their successes to ability an d their failures to bad luck, their good deeds to su p erio r character and their b ad deeds to com pelling circum stance.

O vert Statem ents versus Covert Beliefs

W e shall discuss some of the difficulties accom panying any attem p t to establish that a given attrib u tio n which preserves or enhances the a ttrib u to r’s positive view of him self is biased by self-serving m otives. First, we should note one very obvious conceptual problem that plagues alm ost all research in this area. T h is is the difficulty, first identified by critics of the New Look trad itio n , of distinguishing m otivational effects on covert perceptions or ju d g m e n ts from m otivational effects on overt public behavior (cf. Ross,

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1977b). O bviously, no one disputes that public attrib u tio n al statem ents are influenced by a variety of m otives, including the desire to m axim ize o n e ’s own outcom es and the wish to be well regarded by o n e ’s peers. D ep en d in g on the particular context, the actor m ay show self-aggrandizem ent o r selfdenigration, u n d u e harshness in ev aluating others or great charity, w ithout any corresponding biases in private perceptions. T h e question is and always has been: C an perceptual and cognitive processes be biased by such m otives? T h e problem of in ferring covert ju d g m en ts from overt responses is not unique to the attrib u tio n d o m ain, b u t it is apt to be particularly troublesom e there because there are strong and conflicting m otives that m ay p ro m p t the actor to be less th an candid in his public assessm ents. T h e m otives for claim ing m ore credit than one believes to be o n e’s due are obvious enough. B ut inflated and overly flattering self portraits can get one into trouble. Few m otive states are as intense as the em barrassm en t occasioned by the public failure to live up to o n e ’s self-announced m erits. Im m odest, overly m odest, o r accurate public attributions all m ay be consequences of m otivational factors, an d none can be taken as evidence of correspondingly biased private perceptions. Since there are good reasons to assum e that people often are pow erfully m otivated to offer accurate or even overly m odest attrib u tio n s concerning th eir outcomes, it does not seem su rp risin g that the evidence (review ed by M iller and M . Ross, 1975) suggests that self-serving biases in reported causal attrib u tions are weak, if indeed they are present at all.

W ishes versus T heories in “ S elf-S ervin g” A ttributions

M ost researchers have attem p ted to d em onstrate self-serving biases by showing asym m etries in ju d g m en t, that is, asym m etries in attrib u tio n s of suecess versus failure, asym m etries in the attrib u tio n s of actors versus u n in volved observers, o r asym m etries in the attrib u tio n s for outcom es th a t are high versus low in th eir relevance to the ac to r’s self-concept. M an y published studies have failed to show the expected asym m etries. In d eed , lab o rato ry evidence (and m uch anecdotal evidence as well) leaves little d o u b t th at in some situations actors hold them selves m ore responsible for failures th a n for successes (see Ross, B ierb rau er & Polly 1974). U n d en iab ly , there are m any studies in which actors do seem to take m ore responsibility for successes th an for failures, and there even are a few studies in w hich actors seem to assign credit o r blam e for th eir outcom es in a m ore charitable fashion th a n observers. Even if one overcom es the objection th at the a c to rs’ private perceptions in such studies m ay not correspond to th eir public reports, m ost such Findings, as we shall see, can readily be explained in n o n m o tiv atio n al term s. C onsider, for exam ple, the individual who has am ple reason to regard

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him self as com petent at a given task, b u t fails in a p articu lar attem p t to perform that task. Is he show ing a “ m o tiv atio n al’ ’ bias if he attributes the failure to task difficulty or to chance rath e r than to a new -found incapacity to perform the task? O r is he show ing a stan d ard nonmotivational bias of the type discussed in chap ter 8, that is, the w illingness to assim ilate data about the self to a theory ab o u t the self? As Ross pointed out, in m ost perform ance tests of the type used in outcom e attrib u tio n studies: Success . . . is likely to be anticipated an d congruent with the acto r’s past experience, w hereas failure m ay be u n an ticip ated and unusual. Sim ilarly, successful outcom es are in ten d ed and are the object of plans an d actions by the actor, w hereas failures are u n in ten d ed events which occur in spite of the ac to r’s plans and efforts. (1977a, p. 182) T h u s, a quite dispassionate review of the evidence available to the actor often w ould serve to support the view th at expected and intended success was selfproduced while unexpected an d u n in ten d ed failure was situationally produced. Even though observers m ay reverse this p attern of attributions, it hardly proves the a c to r’s differing perceptions to be ego-defensive. T h e actor m ay be uniq u ely aw are that he previously has been successful in sim ilar tasks, th at he was ex ertin g great effort, or th at changes in strategies were accom panied by im proved perform ance, an d accordingly m ay find it logically com pelling that his success was self-produced. T h e observer m ay prefer a situational explanation of success not because he is disinterested b u t because he is ig norant of the a c to r’s “ privileg ed ” inform ation. By the same token, the acto r’s attrib u tio n s could prove less self-flattering th an could the o b serv er’s in circum stances in which the inform atio n uniquely available to the actor logically w arran ted such seem ingly “ cou n terd efen siv e” assessm ents. P erhaps the m ost su rp risin g aspect of the work on self-serving biases in attrib u tio n s is the astonishingly uncritical reaction it has received from so m any professional researchers. D ata p attern s th at were congruent with the postulated m otivational bias were accepted at face value by investigators, w hen a little th o u g h t should have sufficed to reveal the existence o f equally plausible nonm o tiv atio n al in terp retatio n s of the sam e findings. O ne w onders how strongly the theory o f self-serving bias m ust have been held to pro m p t such uncritical acceptance of em pirical evidence. W e should em phasize that, like M iller an d M . Ross (1975), we have no desire to argue that convincing evidence of self-serving biases will never be found. O n the co n trary , the authors have a hunch th at they personally have erred suspiciously often in the direction of benign self-ascriptions. R esearchers less credulous and m ore sophisticated th an those in the past m ay yet succeed in establishing relatively convincing evidence of these biases in at

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least some dom ains, although the ‘‘track re c o rd ’‫ י‬of those who have sought decisive dem onstrations of m otivational effects m ust te m p er any such optim ism .

T he B asic A n tin om y

W e doubt that careful investigation will reveal ego-enhancing or egodefensive biases in attrib u tio n to be as pervasive or p o ten t as m any laypeople and m ost m otivational theorists presum e them to be. T h e basis for o u r d o u b t was described well by Jo n es and G erard (1967). T hese authors point out th at there is a ‘‘basic an tin o m y ” betw een H e id e r’s “ wish fulfillm ent” and “ d atafitting” criteria for causal attrib u tio n . T h e costs of willy-nilly distortions in perception are simply too high to m ake them a cure-all for the d isappointed or threatened perceiver. In general, m isperceptions m ake us less able to rem edy the situations that th reaten us or give us p ain th a n do accurate perceptions. In a sense, they poorly serve the goals of m axim izing pleasure and m in im izin g pain in the long term, even if the im m ediate cost is the necessity of facing some disagreeable tru th s. T his arg u m en t, obviously, applies not only to the relatively narrow d om ain of causal attrib u tio n s b u t to all p ercep tio n an d cognition. T h e rodent scam pering th ro ug h a field m ight receive sh o rt-term relief if it could perceive the haw klike figure flying overhead as an u n th rea tening dove, but n atu ral selection surely m ust deal harshly w ith such u n restrained subservience of reality to wishes. By the sam e token, the stu d en t who would treat all trium phs as reflective of his tru e abilities and all failures as irrelevant to those abilities m ust ultim ately face far m ore p ain, d isappointm ent, and em b arrassm en t th a n if he acted on less flattering attrib u tio n s. O u r disagreem ent is not w ith the F reudians, for they generally have recognized that defense m echanism s are not b ro u g h t into play every tim e one encounters an aversive fact. T h e F reu dian s em phasized the costs, b o th in term s of psychic energy an d long term ad ap tatio n , th at accrue from heavy reliance on defense m echanism s. T h ey argued th a t the use of p erceptual and cognitive defenses is essentially restricted to circum stances in w hich p articu la r thoughts are too painful or too th reaten in g to be handled in any o th er way. Like m ost F reudians, we doubt that the stan d ard lab o rato ry m an ip u latio n s (which typically involve telling an actor that he has failed at som e task o r has been bested by a peer) involve a serious en o u g h th rea t to p ro m p t the m obilization of drastic “ defensive” m easures. W e are far m ore im pressed by anecdotal and clinical evidence o f individuals who cling to reassu rin g beliefs in the face of seem ingly overw helm ing evidence w hen the im m ediate cost of changing those beliefs threaten s to be devastating. O u r disagreem ent, perhaps, is only w ith those N eo -H u llian s who have been too willing to equate perceptual and cognitive responses w ith those in ­

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stru m en tal actions th at can be shaped by im m ediate rew ards and pu n ish m en ts. O r perhaps we have no q u arrel with any real m otivational “ school.” F or surely no sophisticated H u llian forgot th at responses reflect, at least in p art, long-term reinforcem ent prospects, th at even in frah u m an organism s can curb the tendency to seek im m ediate pleasure w ithout regard for the prospects o f long-term ad ap tatio n . P erhaps the only legitim ate target for o u r com plaints should be the m an y investigators in this trad itio n who have thoughtlessly em b raced facile lay assum ptions about the role of m otive states in perception and cognition.

In form ational Sources o f Self-protective B eliefs

H ow then shall we account for the ap p aren t pervasiveness of people’s tendency to hold u n w arran ted ly positive views of their own attributes? W e already have stressed the extent to which self-serving attrib u tio n s, w hen they exist, m ay be based on a relatively dispassionate assim ilation of d ata to theories about the self. W e m ay add to this th at the available evidence itself m ay be biased to su p p o rt self-serving attrib u tio n s w ithout the necessary interv en tio n of any m otivational distortions in the interpretation of the evidence. C o n sid er the following vignette, by B ertran d R ussell, which H eid er (1958) approvingly quo ted to illustrate the self-serving n atu re of explanations for failure. I am , we will say, a playw right; to every unbiased person it m ust be obvious th at I am the m ost brilliant playw right of the age. N evertheless, for some reason, m y plays are seldom perform ed, and w hen they are, they are not successful. W h at is the ex planation of this strange state of affairs? O bviously, th a t m anagers, actors, an d critics, have com bined against m e for one reason o r another. T h e reason, o f course, is highly creditable to myself: I have refused to kowtow to the great ones of the theatrical w orld, I have not flattered the critics, m y plays contain hom e truths w hich are u n b earab le to those w hom they hit. A nd so my tran scen d en t m erit languishes unrecognized. (R ussell 1930, p. 68.) In o u r opinion, R u ssell’s failed playw right has been not exposed b u t savaged. A nyone who has know n a failed playw right (or m usician or scientist) recognizes that such an individual norm ally has available m uch inform ation th a t w ould be consistent w ith a self-ascription o f talent despite cu rren t failure. H e norm ally has a history of early success (m inim ally school and college suecess) in his chosen field, and has been told by friends (who m ay share his tastes as well as w ishing to please him ) th at the very works th at are disregarded by the public have great m erit. T h e p lay w rig h t’s agent, producers, and financial backers are ap t to have im pressions of the playw right and his

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works that also are atypically positive (or else it would not be they who chose to represent him , or to invest their reputations or m oney in b rin g in g his w ork before the public). T hough our p la y w rig h ts perceptions m ay be free of m otivational biases, his behavior is apt to reflect such biases and thus to expose him to atypically positive, b u t vivid and com pelling, evidence of his talent. N otably, he is apt to spend m ore tim e with his adm irers than with his critics, to seek out those who share rath er than ridicule his artistic views and analysis of his failures. O th er nonm otivational factors fu rth er conspire to support the failed playw right’s self-serving perceptions. It is indisputable that in the th eater and elsewhere a good deal of trash does m eet with po p u lar success, and that deserving work is som etim es recognized only after its au th o r is dead or in dotage. It is then easy for the playw right to assim ilate the available evidence into a fam iliar " s c rip t” or schem a that places a positive in terp retatio n on his fate, for exam ple, the "g en iu s before his tim e ,” whose light will b u rn brightly w hen the panderers to popular taste are forgotten. Finally, there are factors reflecting no inferential shortcom ing a t all. R ew ards are im perfectly correlated with m erit. Every successful scientist of our acquaintance acknowledges the role of good fortune at every career ju n c ture., from being assigned to the right adviser at the right tim e, to b u m p in g into the right problem at the propitious m om ent. O ne em inent psychologist we know characterizes his career as a series of iron gates b an g in g dow n behind him as he am bles blindly dow n the co rrid o r of success: getting into a prestigious graduate school ju s t before they stopped ad m ittin g people of his m eager qualifications, getting an excellent first jo b ju st before the com petition for such jobs becam e fierce, and so on. U nless we wish to call these beliefs on the part of successful scientists " c o u n te rd e fe n siv e ,” we have little need to label the com plem entary beliefs of failed scientists or artists " d e fe n s iv e .” It seems m ore parsim onious to say that both successful and unsuccessful people believe, with good justification, that career outcom es are im perfectly correlated with effort or talent. Let us em phasize again that we have no wish to deny that people, ineluding R ussell’s playw right, are m otivated to see them selves in the best possible light. W e even share R u ssell’s and H e id e r’s suspicion that this m otive can som etim es color, indeed even inspire, a p attern of attrib u tio n s not uniquely dictated by the available d ata. W e m erely dispute the existing laboratory evidence for such a bias, and deny that such biases are solely or even largely responsible for all ju d g m en ts that are on the surface self-serving. W hen m otivational biases exist, m oreover, we suspect that they rarely fly in the face of reality. T hey are usually su p p o rted , even en co u rag ed , by the available evidence. W here m otivational biases undoubtedly do play a role, is in shaping the acto r’s behavior, in p ro m p tin g him to expose him self to m ore pleasant and

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favorable evidence, in m aking him relu ctan t to expose him self to less flattering evidence, and in en co u rag in g o th er actions that by accident or by design serve to ease the pain of failure or to heighten the pleasure of success. T h u s an individual can say quite correctly that “ the people I know seem to like my w o rk ,” while being blind to the fact that it is in part for that very reason that he know s them .

E T H N IC P R E J U D IC E : H E A R T S O R M IN D S ?

P erhaps no cognitive tendency is m ore universally attrib u ted to m otivational, em otional, or spiritual defects th an is racial or ethnic prejudice. Prejudice is denounced from the pulpits of clerics, jo u rn alists, and social psychologists alike as a d eran g em en t of the passions, as a triu m p h of the h eart over the intellect. Serious reflection on the topic (and the serious reflections to w hich we are m ost indebted in this section are those of Icheiser, 1949 and M cC auley, in press) raises questions as to w hether the right organ has been singled out for blam e.

W hat is the M o tive B ehind Stereotypes?

F irst, w hat exactly is the m otive for prejudice? M arxists will have a ready answ er: It is econom ic self-interest or, less politely, greed. W hites are prejudiced against blacks because such prejudice justifies their exclusion from fair econom ic com petition. G entiles are prejudiced against Jew s because of their econom ic success. O f course, “ en v io u s” anti-S em itism works best for contem p o rary A m erica, w here Jew s have been econom ically successful; in earlier periods in E urope and A m erica the prejudice m ust have had a different basis, perhaps the “ exclusion from co m p etitio n ” m otive. M an y non-M arxists are skeptical of the econom ic self-interest theory precisely because of this sort of facility. Skepticism should be increased by a consideration of prejudices against groups (for exam ple, T u rk s, B uddhists, and so on) whose econom ic position in A m erica is unexceptional or unknow n o r otherw ise irrelevant to the prejudiced in d iv id u al’s fate in the com petition for access to goods an d services. Is prejudice perhaps a p ro d u ct o f fear, a holdover from early m an staring grim ly out of his cave at the suspicious stranger? It seems tru e th at, in co n tem p o rary A m erica at least, m an y whites are deeply afraid of blacks and vice versa. B ut are A m ericans typically afraid of Jew s? or Poles? or T urks? C an sheer m alevolence be the answ er— the m a ra u d in g tribesm an in us, su b stitu tin g thoughts an d w ords for the sticks and stones of earlier eons? T his

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in terp retatio n is perhaps the least plausible of all because there are few unam • bivalent stereotypes: Blacks are labeled as stupid, lazy, and crim inal, b u t they also are characterized as strong and athletic, an d as having rh y th m an d soul. Jew s are said to be crafty, clannish, an d loud, b u t they also are said to be intelligent and unusually willing to care for th eir own u n fo rtu n ates. Som e ethnic stereotypes, m oreover, are substantially m ore favorable th an unfavorable: T h e stereotype of the English, for exam ple (excepting of course the Irish version of the stereotype), is on balance ra th e r enviable. A second serious problem w ith the ‘‘h e a rts” hypothesis of prejudice is that the stereotypes held by the various group m em bers them selves often differ little from those held by the larg er society. Self-stereotypes often m ay accentuate the positive, b u t they rarely are unrecognizably different from those of the o u tgroup. W hen self-stereotypes are actually neg ativ e— as negative, in some cases, as o u tg ro u p stereotypes a re — the ‘ ‘h e a rts ” hypothesis does not falter; it sim ply postulates ‘‘self-hate” as the explanation for the negative self-characterization. P erhaps the m ost serious problem w ith the hearts hypothesis is th at it fails to acknowledge that there are “ stereotypes’’ for alm ost every category of people. T h ere are stereotypes of lib rarian s, engineers, p rostitutes, professors, old people, young people, B aptists an d R o tarian s; people w ho w ear beard s or beads, people who w ear grey flannel suits or h ard hats, people w ho drive Cadillacs or V olksw agens, people who jo g an d people who have sw im m ing pools. A re these stereotypes all to be seen as subservient to econom ic m otives, or fear, or m alevolence tow ards strangers? If not, why should ethnic or regional stereotypes u niquely be singled out as passion-produced? Surely it is sim pler and m ore reasonable to look to m echanism s w hich m ig h t apply equally well to both affect-laden and affect-free stereotypes. Such a search inevitably takes us from the h eart to the head, the place w here we norm ally look to u n d erstan d the fo rm ulation an d p erseverance o f generic beliefs, not ju st beliefs ab o u t blacks or T u rk s or lib rarian s, b u t also about oak trees or restau ran ts or elephants.

T heory vs. D ata in the Form ation and M aintenance o f Stereotypes

T h e m ain origins of stereotypes about people, w hether pejorative or otherw ise, seem clear enough. People believe th at blacks are lazy or th a t Jew s are clannish because some person (or cartoon, jo k e, television p ro g ram , story, or song) told them so. In d eed , if we take the im plications of ch ap ter 5 seriously, there are not really m an y alternative possibilities. For, even if the stereotype enjoyed some em pirical validity, and even if the person h ad enough inform ation to generate the stereotype, p eo p le’s covariation detection

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capacities are far too cru d e to allow any such purely “ d ata-b ased ” discovery. T h e m ost un reaso n in g bigot w ould have to concede that the condition of virtually perfect covariation (to say noth in g of ideal data storage an d display) necessary for data-b ased covariation detection is not m et in his “ d a ta ” associating p articu lar personality traits w ith p articu lar races or ethnic groups. It should be noted th a t in teresting recent work by H am ilto n and his colleagues does suggest th at som e erroneous ethnic stereotypes m ight be “ datad riv e n ” in p art. T h e ir research shows that w hen m em bers of group A are m ore n u m ero u s th an m em bers of group B, an d w hen desirable behaviors are m ore freq u en t th a n und esirab le behaviors, the (distinctive) undesirable behaviors will be rep o rted , erroneously, to be m ore characteristic of (distinetive) group B than of group A (H am ilto n an d G ifford 1976; H am ilto n 1976; also R o th b a rt and colleagues 1978). Such an “ illusory co rrelatio n ” m echanism m ay well play a role in m ajority group beliefs about m inorities. W e suspect, how ever, th at it is cu ltu ral transm ission in its various form s that is chiefly responsible for sowing the seeds of prejudice. Beyond the problem of th eir origins, how do stereotypes persist so strongly? O ften they seem to survive in the absence of any d ata w hatsoever, as in the case of stereotypes of T u rk s, an d , for m any people, of T exans, Poles, Jew s, or blacks as well. People m ay quite reasonably presum e th at the culture w hich has provided them so econom ically with so m any tru th s about covariations an d functional relationships also has got the facts right in this case. (O r m ore accurately p erhaps, people m ay not exam ine the original bases for their stereotypes any m ore th an they scrutinize o ther culturally tran sm itted beliefs.) In the event that the individual does have some d ata it is very unlikely that the data will serve to disconfirm the belief. T o begin w ith, the individual is likely to en co u n ter at least som e entries in the “ p resen t/p resen t” cell (cf. ch ap ter 5). A nd people are inclined to give such cases exclusive, or at least d isp ro p o rtio n ate, w eight. O n e of the present au th o rs, on his first trip to Italy, spent m ost of his tim e in R om e. T h e closest he had com e previously to direct encounters w ith Italians (other th an Italian-A m ericans) h ad been his exposure to com edies ab o u t Sicilians, on the o rd er of the film Divorce Italian Style. T h o u g h he was thrilled by the sights of R o m e, he was som ew hat disappointed by the R om ans them selves. Svelte, sophisticated urb an ites, they seem ed “ u n re p re se n ta tiv e ” of Italians. O n a bus taken for a side trip outside R om e, how ever, the au th o r saw an obese, w arm , d em o n strativ e w om an clucking over h er brood of four children. N ow the au th o r was able to leave Italy conten t th a t he had finally seen a “ re a l” Italian , an d indeed he felt reassured that at least the “ re a l” Italians were very m uch as he h ad thought them to be. S ubtler, perhaps, are those cases in w hich the m aintenance of a stereotype is ab etted because th at stereotype enjoys a kernel of, if not tru th , at least fact. T h e sam e au th o r m en tio n ed above recently took a lengthy to u r of

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S candinavia. O ne day, at a railroad station, he and his wife h ad been prow ling for some m inutes am ong the lockers looking for an em pty one. F in d in g one at last, the au th o r shouted to his wife: “ H ey, th e re ’s one over h e r e .” Before the echo had died, the au th o r realized th at his was the only voice he had h eard raised d u rin g several weeks of traveling in Scandinavia. Such an incident m ight legitim ately help to confirm the S can d in av ian s’ stereotype of A m ericans as loud. W e suspect, how ever, th at m inim al confirm ation of any part of a stereotype is taken by the stereotype-holder as evidence for the whole set of connotatively or sem antically linked traits em braced by the stereotype. T h us, the incident m ight have served to “ v a lid a te ,” for S candinavians present in the rail station, a m uch b ro ad er stereotype th an one involving sim ple loudness (that is, the stereotype of A m ericans as u n co u th , u n cu ltu red , boorish, an d overbearing, perhaps even m aterialistic or im perialistic). In addition to the availability of at least som e confirm ing cases (in anecdotes or m edia portrayals, even if som etim es not in personal experience), the whole panoply of m echanism s discussed in chapters 4 an d 8 m ay be expected to come into play. Biased assim ilation of evidence— coding an d storing am biguous data in a m an n er that serves to bolster o n e ’s theory or stereo ty p e— is one m echanism that students of prejudice have noted repeatedly. T h e ad u lt black, observed sitting on a park bench at 3 p . m . on a W ednesday m ig h t be coded as unem ployed, lazy, and probably on w elfare, w hereas a w hite observed in sim ilar circum stances w ould m ore likely be given the “ benefit of the d o u b t” ; that is, to be coded as enjoying a day off, relaxing before b eg in n in g work on the night shift, or even as being the innocent victim of recession layoffs. O th er, less fam iliar m echanism s of a type described in ch ap ter 8 m ay play a role. T h e propensity to form causal explanations seems p articu larly relevant here. Such a propensity m ay have even g reater im pact on the perceptions of the person who w ould deny his bigotry th an on the person who w ould seek to justify it. For instance, it is the “ classic lib eral” who hastens to form ulate situational or societal explanations for the “ p h e n o m e n a ” th at figure in racial stereotypes (for exam ple, blacks are not inherently lazy, o r unm otivated, or crim inally inclined; it all is a result of the “ culture of p o v erty ” or of the “ father-absent sy n d ro m e” or of the “ anom ie born of oppression and pow erlessness” ). W h eth er justified or not, such explanatory “ th eo ries” potentially can do m uch to m ain tain stereotypes in the face of logical or em pirical challenges (cf. B ennett 1978). Finally, we should not ignore the fact th at stereotypes, like other beliefs, are acted upon. T h e m ain ten an ce of a stereotype m ay take on a genuinely m otivational character w hen the actor calls upo n the stereotype to ju stify actions of seem ing unfairness. Even m ore im p o rtan tly , som e stereotypes have the capacity to becom e self-fulfilling. T h e w illing w orker denied a jo b because of a stereotype suggesting he will be lazy becom es a p rim e can d id ate for the

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park bench an d therefore a seem ing justification for the stereotype that helped to place him there. W e have argued th at there is no com pelling reason to assum e that ethnic stereotypes differ in th eir origin or n atu re from any o ther kinds of stereotypes, o r for that m atter from any o th er beliefs, good or bad. T h is is not to say that stereotypes, once held, cann o t lead to effects w ith m otivational significance. As Brow n (1965) pointed o u t, the belief in ethnic differences can fuel resentm ent once conflict occurs. M ore im po rtan tly , stereotypes can and do lead to d am ag in g b ehavior tow ard individuals. E thnic stereotypes an d the actions they pro m o te, in short, u n d en iab ly have pernicious consequences. W e believe it is for this reason th at th eir causes are so widely believed to be pernicious.

Irrational B eliefs A bout H um an Irrationality

C o n sid er again the em ployer w ho fails to hire a black person because of his race. H e un d en iab ly h arm s th at person. In the m ind of the observer the h arm ful action m ay readily be attrib u ted to a corresponding harm ful in tent or m alevolent disposition. T h e em p lo y er’s m otives then are seen as evil, and the origin of the stereotypes which he uses to ju stify his action also seems to be evil. It is sim plistic an d u nnecessary to m ake eith er inference. Socially dysfunctional discrim in atio n in hirin g m ay no m ore reflect evil m otives than personally dysfunctional co n su m er preferences do. But for m ost social observers, relatively m u n d a n e processes o f the sort th at m ake people persist in th eir choice of la u n d ry d etergents sim ply seem u n rep resen tativ e as potential causes of an effect as m anifestly evil as the im poverishm ent an d degradation of a racial group. People are often o u trag ed , in fact, w hen it is suggested to them th a t evil actions can have th eir origins in an y th in g oth er than evil m otives, as w itness the reaction to H a n n a h A re n d t’s (1965) thesis of “ the banality of e v il.” She suggested th at A dolph E ich m an n , the m an who oversaw the ex term in atio n of E u ro p ean Jew ry , was a m ere b u reau c ra t, a m an w ith no g reater passion for elim in atin g Jew s th an an o th er b u reau c ra t m ight have for shipping the m ail. T o people who believe that m otives m ust m atch acts, such a thesis is unacceptable. In short, it is the em ploym ent of the representativeness heuristic an d the susceptibility to the fu n d am en tal a ttrib u tio n e rro r th at produce psychodyn am ic theories of h u m a n irratio n ality . If destructive social actions m ust reflect correspondingly evil m otives, then psychodynam ic theories becom e essential. Sim ilarly, if favorable opinions ab o u t oneself m ust reflect a corresp o n d en t m otive to hold such favorable opinions, then the ascription o f selfserving biases an d ego-defensive m otives w ould seem inevitable. By the same

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token, the existence of highly negative self-evaluations m ust be attrib u te d to m asochism an d self-hate. W e are rem in d ed of the psychoanalyst who accused patients who cam e late of hostility, those who cam e early of defensiveness, and those who cam e on tim e of com pulsiveness. In fact, we are rem in d ed of psychoanalytic theory.

P S Y C H O A N A L Y S IS , P S Y C H O D Y N A M IC S , A N D T H E R E P R E S E N T A T IV E N E S S H E U R IS T IC

T h e previous chapter an d this one have dealt w ith topics th at u n til recently have been the alm ost exclusive preserve of psychoanalytic theory. It seems fitting, therefore, to conclude this chapter by discussing the relationship betw een the view of h u m an inference and e rro r offered in this book an d the orthodox psychoanalytic view. In M ind and Emotion (1975), M an d ler predicted th at cognitive psychologists soon would rediscover psychoanalytic constructs b u t w ould find it convenient and even necessary to use a m ore m o d ern term inology for them . In our opinion, two of the m ore basic ideas in this book do a m o u n t to a rediscovery of two of the most im p o rtan t ideas w ith which F re u d ’s nam e an d the psychoanalytic tradition are associated. O n e of these is the notion th at m uch of m ental life is inaccessible to introspection, th at is, is unconscious. W e share this view point w ith psychoanalytic thinkers (an d w ith M an d ler) though, as we soon will m ake clear, o u r view of the reasons for lack of access to some of the facts of m ental life, an d o u r view of the possibility of increasing th at access, differ from traditional psychoanalytic views.

R epresentativeness and A ssociative N etw orks

T h e second fundam ental idea has no real nam e in psychoanalytic term inology, although it involves an aspect of “ prim ary process” thinking. It has a m odern nam e, how ever. T o us, the cornerstone, the chief co n trib u tio n , an d the Achilles heel of psychoanalytic th o ught all are o n e— F re u d ’s discovery, for it was his, o f the enorm ous im portance to m ental life of the representativeness heuristic. M ost thoughtful psychologists probably w ould agree w ith F reu d that (a) one thing can stand for an o th er, in w aking life and in dream s; (b) the link betw een the symbol and the th in g th at it “ stands fo r” is th eir sim ilarity on some salient dim ensions, how ever idiosyncratic, illogical, or b izarre those dim ensions m ight be; and even (c) that the individual then m ay behave tow ard the symbol in the same way he w ould behave tow ard the th in g itself.

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F rom his analysis of Little H an s to his account of slips of the tongue in everyday life, F reu d is m ost convincing, and his brilliance is m ost ap p aren t, w hen he assum es the m antle of detective an d pursues the trail of representativenessbased associations. F reu d not only pointed to the im portance of the representativeness heuristic in daily life; he also provided a technique for discovering w hat stands for w hat in the m ental life of a given person. T his technique is free association, in w hich the p atien t is in structed to say everything that comes into his m in d w ithout censorship o r concern for logical connections. T he assum ption beh in d the technique, co n g ru en t w ith general psychological assum ptions since n in eteen th cen tu ry British associationism , was th at the o rd er in w hich verbal m aterial is p roduced by such a process is not random or a rb itra ry but instead reflects sim ilarities an d causal connections in the m ind of the individual. W h en , im m ediately after speaking of his analyst, the patient then speaks ab o u t a traffic policem an he has seen the day before, the analyst presum es the idea o f analyst to be connected w ith th at of policem an by some notion of representativeness, sim ilarity, or ‘‘stan d in g fo r” in the m ind of the p atien t. N o th in g in cu rren t psychological theory or research casts doubt on the validity of such a presu m p tio n , and there is m uch th at supports it. A m ajo r problem w ith the assum ption (even in F re u d ’s hands, but especially in the hands of m an y followers) is the u n certain ty of criteria for d eterm in in g w hen it is the p a tie n t’s associative netw orks that have been laid bare a n d w hen it is the an aly st’s. T h e lack of such criteria is especially evident in such dubiou s exercises as the psychoanalysis, based on frag m en tary and secondhand reports, of historical figures w hom the analyst has never m et. T h e sam e theory and m ethods th at yielded F re u d ’s most com pelling analytic insights underlie the analyst A b rah am sen ’s (1977) “ discoveries” about R ic h a rd N ixon. T h e ten y ear old N ixon app aren tly was p ro u d of his ability to m ash potatoes so sm oothly th at there were no lum ps. Potatoes, A braham sen solem nly observes, w ere a substitute for people. T o o u r know ledge, psychoanalysis has nev er adequately dealt w ith the problem o f identifying w hether a given link exists in the head of the patient or only of the analyst, an d this w eakness has been responsible, perhaps m ore th an any other, for exposing the F reu d ian trad itio n to scholarly skepticism . A psychoanalyst whose nam e is w idely know n to A m erican psychologists and to the b ro a d e r intellectual com m u n ity once was h eard to m use, at a case conference: “ H m m , the p atien t used the w ord ‘h an d le ’ several times. D o we have a problem w ith m a stu rb atio n h e re ? ” W as this a b rilliant analytic insight, o r was it m erely a reflection of the cognitive processes an d associations of the em in en t analyst? W e suspect the latter. As the father of the psychoanalytic trad itio n him self once rem ark ed , “ som etim es a cigar is only a c ig a r.” U n fo rtu n ate ly he did not pass on the rules for m aking such discrim inations to m an y of his m ost outspoken disciples.

Representativeness and Causality T h e problem of auth en ticatin g the an aly st’s guesses about the p atien t s connotative networks pales in significance beside a far m ore d ev astatin g weakness. T his was F re u d ’s tacit assum ption that the scientist could discover the true causes of h u m an behavior by w hat am ounts to an exercise of the representativeness heuristic: B ehavior, once its “ re a l” m ean in g was uncovered by the analyst, could be traced to correspondent m otive states and dispositions. In m aking this assum ption, F reud risked elevating the fundam ental attrib u tio n e rro r to the status of a scientific principle. T h e wish was to be father to the deed, and all deeds were to be traced to wishes w ith recognizable parental features. So com m itted was F reud to this strategy for causal analysis that he was led, by w itnessing the slaughter of W orld W a r I (and by the newly observed clinical syndrom e of m asochism ), to incorporate into his theory the notion of the death instinct. Like all events, the phenom enon of young m en m arching off to a likely death in the m uddy, stinking trenches of that w ar required a dynam ic explanation. Since cause must m irror effect, and the effect was death, the cause m ust be a wish for death. T he enorm ous popularity of F reu d ian theory probably lies in the fact that, unlike all its com petitors am ong contem porary views, it encourages the layperson to do w hat comes naturally in causal explanation, that is, to use the representativeness heuristic. Psychoanalytic theory shares with lay views not only a general causal analytic strategy, b u t specific assum ptions ab o u t causality for particular types of events as well. T h e C h a p m a n s’ w ork, discussed at length in chapter 5, illustrated the rem arkable overlap betw een the a n aly st’s beliefs about covariation betw een signs and sym ptom s and the verbal associations and naive theories of the layperson. It m ight be objected that at least some of the specific causal hypotheses of psychoanalytic theory do not correspond to lay hypotheses, m ost notably the great causal significance attached to childhood sexuality. T his is tru e, b u t while the theory of childhood sexuality was shocking and at odds w ith some contem porary views of children, it did not com pletely violate representativeness criteria. O n the contrary, childhood sexual experience is highly representative as a general causal factor both because of its significance (sexuality is very im p o rtan t, thus a good causal candidate w ith respect to m agnitude for m any equally im p o rtan t effects) and its tim in g (things that happen early should be form atively im p o rtan t, hence causally im p o rtan t). In addition, once one entertains the theory that sexuality determ ines beh av io r of all sorts, it is child’s play (p u n intended) to generate sexual explanations through the use of the representativeness heuristic. For exam ple, the a u th o r now is using his pen trying to m ake a mess of w hat he finds repellent in psychoanalytic theory, while sim ultaneously trying to retain w hat he finds attractive in the theory. 244

The Unconscious and Repression T h e autho rs share w ith psychoanalytic theorists the view that m uch, if not m ost, of m ental life is inaccessible to conscious experience. In the view of the au th o rs, how ever, w hat is unconscious is norm ally unconscious for the sim plest of reasons: People lack the m achinery for brin g in g the relevant facts into conscious purview . W e often do not know why we like or dislike an o th er person for the sam e reason th at we do not know why we perceive an object to be at a given distance. T h e processes th at produce affective ju d g m en ts, like the processes th at produce ju d g m en ts of depth, are n eith er verbal in n atu re n o r directly accessible to introspection. T h e psychoanalytic account is q uite different: In F re u d ’s opinion, m uch (th o u g h not m ost) of w hat is inaccessible has been repressed. U n pleasant facts are unavailable to the person because the person does not wish to know them . Such a conclusion is the n atu ral consequence of the th e o ry ’s reliance on the representativeness heuristic an d its susceptibility to the fundam ental attrib u tion erro r. A n act m ust be p roduced by a correspondent m otive; hence the “ a c t” of not know ing an u n p leasan t m ental fact m ust be due to a desire not to know it. W e do not w ish to argue th at there is no such thing as repression. W e personally do not d o u b t th a t people som etim es “ d e n y ” the existence of th rea ten in g facts an d exert psychic energy in their attem pts to avoid recognizing them (although, like Erdelyi & G oldberg 1978 we are far m ore im pressed by clinical evidence than by p u rp o rted d em onstrations in the laboratory). W e suspect, how ever, th at people norm ally fail to recognize the existence of painful psychological facts for the sam e reason that they fail to recognize painless o n es— because they are inaccessible. W hen the painful fact is pointed out to the individual, he m ay deny its existence for the sam e reason that subjects in the N isbett an d W ilson studies denied the existence of quite painless facts— because they are im plausible. O u r view also differs from the psychoanalytic view on the question of how to m ake the individual aw are of unconscious m aterial. Freud was quite explicit on this point: If we com m unicate to a p atien t som e idea w hich he has at one tim e repressed b u t w hich we have discovered in him , our telling him does not rem ove the repression n o r u n d o its effects, as m ight perhaps be expected from the fact th at the previously unconscious idea has now becom e conscious. O n the co n trary , all that we shall achieve at first will be a fresh rejection of the repressed idea. At this point, how ever, the p atien t has in actual fact the sam e idea in two forms in two separate localities in his m ental ap p aratu s: first, he has the conscious m em ory of the au d ito ry im pression of the idea conveyed in w hat we told him , and, secondly an d side by side w ith this, he has— as we know for c ertain — the 245

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unconscious m em ory of his actual experience existing in him in its earlier form . N ow in reality there is no lifting of the repression u ntil the conscious idea, after overcom ing the resistances, has u n ited w ith the unconscious m em ory-trace. O nly th ro u g h b rin g in g the latter itself into consciousness is the effect achieved. (F reu d 1915/1959, p. 108) F reud believed that direct access to norm ally unconscious facts was a possibility. T h ere is a “ m em o ry -trace” to w hich the th e ra p ist’s suggestion can be connected. In o u r view, there norm ally would be no m em ory-trace to be prim ed, excited, or retrieved. T h e unconscious fact, w h eth er u n p leasan t o r not, can only be inferred, not discovered. A n exam ple m ay clarify this difference of opinion. B ehavior therapists S tu art an d D avis (1972) believe th at m any husbands of the obese w om en w hom they treat have an in v estm en t in their w ives’ unattractive states. T h e h u sb an d m ay have struck a tacit b argain: Y our obesity for my im potence (or m y alcoholism , or m y failure in m y profession). T h e weight loss of the wife therefore is often th reaten in g to such a m an and he sabotages the diet ( “ I really liked you b etter the way you w ere” ). T h e m an who feels threaten ed by his w ife’s increasing attractiveness m ight benefit from becom ing “ aw are” of this fact. T h e F reu d ian view w ould seem to be that such insight can be accom plished if, an d only if, the th e ra p ist’s assertion m akes contact w ith the clien t’s repressed know ledge of the fact. In ou r view, there generally is no such know ledge to be “ co n ta c te d .” If the client is to be m ade aw are of his hidden m otive, it m ust be m ade plausible to him . T h e therapist m ight note for the client, for exam ple, th at his last two big benders were associated w ith his w ife’s successful attem p ts at w eight loss, or that the client seems oddly concerned w ith the cost of a new , sm aller size w ardrobe, an d so forth. In short, the therapist m ust present evidence th at the client will have difficulty in explaining plausibly if he does not resort to the th e ra p ist’s hypothesis. U ndoubtedly, the p atien t will not yield w ithout offering sub stan tial “ resistan ce,” and undoubtedly such resistance, w hich m ay take the form of offering alternative explanations and “ contradictory d a ta ,” is in p art defensive. But note that the th e ra p ist’s hypothesis is, in fact, also implausible in view of lay theories about husbands, wives, an d fem inine attractiveness. T h e lay view is that m en like to be m arried to the m ost attractive w om en possible. A desire to have an u nattractive wife is, especially to psychologically unsophisticated people, a notion fully as odd as it is th reaten in g . T h e “ discovery” of its tru th , if it is m ade, is an inference from the available d ata, for the p atien t ju s t as it is for the therapist. T he resistance to such discoveries is no m ore rem ark able than the “ resistance” of any form al scientist to u n u su al propositions challenging a Firmly en tren ch ed theory. It is interesting to speculate w hether therapists m ight en co u n ter less resistance to their in terp retatio n s if they were to acknow ledge th at it m ight be

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caused by som ething other than ego defensiveness. A client who is told that he is 4‘resistin g ” an in terp retatio n only in o rd er to protect him self and th at he could “ see” the psychological facts for him self if he were willing, seems likely to co ntinue the struggle. H e m ight be less inclined to resist if he were told th at, though the in terp retatio n seems unlikely in view of com m on-sense notions ab o u t h u m an behavior, an d though his psychological states can no m ore be “ seen ” by the client than by the therapist, such an interp retatio n seem s m ost consistent w ith the facts available to both the client and the therapist.

SUM M ARY

A lthough erro rs in inference or b ehavior som etim es seem to reflect m otives, inform ational or intellectual factors are often im plicated in such errors. W hen self-serving m otives such as ego defensiveness or ego enhancem en t are influential, the effect seldom is due to “ d irec t” distortion of perception or ju d g m e n t. R a th e r, the m ed iatin g role of behavior, which indisputably is influenced by the a c to r’s m otives, b u t also indisputably changes the n atu re of the inform ation available to the actor, seems crucial in a great m any cases. A ttem pts to d em o n strate conclusively the effects of m otives on covert perceptual, cognitive, o r inferential processes have a long an d far from encouraging history in psychology. Classic learn in g theorists, and researchers testing the “ N ew L o o k ” hypothesis, en co u n tered the difficulties both of ruling out nonm otivational in terp retatio n s for seem ingly m otivational phenom ena and of proving th at there were m otivational effects on covert processes rath e r than m erely on overt responses. T w o cu rren t debates seem to be resurrecting the sam e issues an d ultim ately the sam e interp retativ e difficulties: O n e debate is on the role of self-serving biases in the attrib u tio n of positive versus negative personal outcom es. T h e oth er is on m otivational versus cognitive sources of racial and ethnic prejudice. E x am inatio n of these topics suggests that m otivational in terpretations, despite their intuitive appeal, are hardly d em an d ed by the evidence. In both cases n o nm otiv atio n al factors seem sufficient to account for m ost of the p h en o m en a. In the case of so-called ego-defensive biases in attrib u tio n , it is clear that actors usually hold preconceptions an d possess evidence that on purely intellectual g rounds w ould seem to ju stify , if not d em an d , asym m etric responses to success an d failure. In the case of prejudice, it seems clear that stereotypes of ethnic or racial groups are sim ilar to the schem as or theories th at encapsulate socially based know ledge of m any o ther categories of people, objects, or events. M ost im p o rtan t, the persistence of u n w arran ted stereotypes despite logical or evidential attack seem s qu ite explicable by nonm otivational

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processes. T hese include the assim ilation of available in fo rm atio n to preconceptions, the form ation of causal theories, an d the bolstering effect of belief-relevant behavior, all of which conspire to give stereotypes the illusion of im pressive em pirical support. T o us, the real phenom enon to be explained is the w idespread an d generally uncritical acceptance of m otivational explanations for erro n eo u s and dam aging beliefs. P eo p le’s use of the representativeness h euristic in general, and their susceptibility to the fu n d am en tal attrib u tio n e rro r in particular, seem to be reflected in th eir tendency to em brace m otivational explanations. Psychoanalytic theorists have recognized, as o th er theorists som etim es have overlooked, th at u n b rid led distortion of perceptual an d cognitive processes are generally held in check by the o rg an ism ’s need to respond adaptively to its environm ent. T h ey also have offered u n iq u e insights into the com plex, often “ representativeness-based” links betw een covert processes and overt responses. But p roponents of psychoanalysis seem seriously comprom ised by th eir own w illingness to link beh av io r to u n d erly in g needs, wishes, or m otives on the basis of relatively crude resem blance criteria.

11 assessing the damage

If we’re so dumb, how come we made it to the moon? A colleague (upon reading preliminary drafts of chapters 1 through 8).

M an y people vigorously protest the view of h u m an inferential abilities presented in this book. T h ey argue that people’s inferential triu m p h s are far m ore im pressive, and far m ore typical, than their failures. D ram atic suecesses such as placing astro n au ts on the m oon, cracking the genetic code, and unlocking the secrets of the atom , and the less dram atic ones that perm it us to enjoy a generally harm o n io u s and com prehensible w orld, do raise some imp o rta n t questions. H ow can o u r species’ unparalleled inferential accom plishm ents be reconciled w ith this b o o k ’s seem ingly u n flattering p o rtrait of lay inference? M o re to the point, perhaps, have the present authors been unfair in their choice of research and anecdotes? H ave we sensitized the read er to instances of inferential folly and thereby fostered highly distorted estim ates of the ratio of failures to successes that m ight be revealed in a m ore exhaustive or less biased survey? M o st im p o rtan t, w ould such a survey show norm atively in ap p ro p riate inferences to be restricted largely to contexts in w hich such errors are inconsequential or even functional for the layperson? 24 9

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Such questions about the actual dam age done by the strategies an d tactics of lay inference are the focus for this chapter.

R E C O N C IL IN G IN F E R E N T IA L T R IU M P H S W IT H IN F E R E N T IA L F A IL U R E S

T he Trium phs: C ollective and N o n in tu itiv e

A lthough the challenge to reconcile o u r point of view w ith m oon landings an d the like is som ew hat playful, it does force us to begin o u r assessm ent of dam age by em phasizing how seldom is h u m an society totally at the m ercy of intuitive inferential strategies. H u m an s did not “ m ake it to the m o o n ” (or unravel the m ysteries of the double helix or deduce the existence of quarks) by tru sting the availability and representativeness heuristics or by relying on the vagaries of inform al d ata collection and in terp retatio n . O n the co n trary , these trium phs were achieved by the use of form al research m ethodology an d norm ative principles of scientific inference. F u rth erm o re , as D aw es (1976) pointed out, no single person could have solved all the problem s involved in such necessarily collective efforts as space exploration. G ettin g to the m oon was a jo in t project, if not of idiots savants, at least of savants whose individual areas of expertise were extrem ely lim ited— one savant w ho knew a great deal about the propellant properties of solid fuels b u t little about the guidance capabilities of small com puters, an o th er savant who knew a great deal ab o u t the guidance capabilities of small com puters b u t virtually no th in g ab o u t gravitational effects on m oving objects, an d so forth. Finally, those savants included people who believed that redheads are ho t-tem p ered , who bo u g h t their last car on the cocktail-party advice of an a cq u a in ta n ce’s bro th er-in -law , an d whose m astery of the form al rules of scientific inference did not notably spare them the social conflicts and personal d isap p o in tm en ts experienced by their fellow hum ans. T he very im pressive results of organized intellectual endeavor, in short, provide no basis for contradicting o u r generalizations about h u m a n inferential shortcom ings. T hose accom plishm ents are collective, at least in the sense that we all stand on the shoulders of those who have gone before; an d m ost of them have been achieved by using norm ative principles of inference often conspicuously absent in everyday life. M ost im po rtan tly , there is no logical contradiction betw een the assertion th at people can be very im pressively intelligent on some occasions or in some dom ains an d the assertion th at they can m ake how ling inferential errors on o th er occasions or in o ther dom ains.

The Failures: Limited to the Laboratory? T h e com plaint th at the p resen t au th o rs have been u n fair and u n rep resen tativ e in th eir ‘‘sam p lin g ” is less easily dism issed. M ore th an once the suspicion has been voiced th a t investigators w orking in this tradition have a sharp eye for the occasional ju d g m en tal frailty an d th at they craftily construct laboratory experim ents to exploit such lapses. T h e im plication is that the investigators are try in g to pass off a few puckish dem onstrations as a faithful p o rtra it of h u m a n inferential incapacity. In som e ways we w ould plead guilty to at least a m u ted version of this charge. Indeed, one goal of this ch ap ter will be to flesh out the ‘‘biased samp lin g ” objection and explore the possibility th at the actual everyday dam age done by the lay p erso n ’s shortcom ings m ay be relatively slight. H ow ever, com plaints abo u t the heavy use of laboratory dem onstrations occasionally carry a fu rth er im plication. T h ey som etim es im ply that it is only in the laboratory th at one can d em o n strate the overutilization o f intuitive strategies or the u n d eru tilizatio n of n o rm ative ones. W e ad am an tly reject this view. W e insist th at the errors d em o n strated in the laboratory an d chronicled in this book are the ingredients of individual and collective h u m an tragedy. O u r im patience w ith critics who w ould dismiss the laboratory evidence as the hothouse p roducts of devious experim enters is based on o u r belief that such critics fail to com pare the pitfalls faced by the subject in the laboratory tasks w ith those that the sam e person is likely to face in everyday behavioral or ju d g m e n ta l dilem m as. As we noted at several points, the lab o rato ry procedures often lead to an underestimation of the m ag n itu d e of p articu lar inferential failings. O n e exam ple is the crucial task of detecting covariation. Recall that the laboratory tasks alm ost always presented subjects w ith already “ prep ack ag ed ” and highly ‘‘processed” data. By contrast, in everyday experience, observers m ust decide for them selves w hich data are p ertin en t and how they are to be sam pled, m ust resolve any am biguities in coding, m ust store and retrieve the data, an d m ust find a way to aggregate and display the data. O r recall the research on the lay p erso n ’s tendency to m ain tain im pressions or beliefs after their evidence base has been thoroughly discredited. In the laboratory, the discrediting m an ip u latio n s w ere com pletely decisive and they followed alm ost im m ediately upo n the initial receipt of the evidence. In the real w orld, discrediting is rarely eith er im m ediate or incontrovertible. T ypically, attacks on the evidence th at p ro m p ted initial beliefs are them selves subject to altern ativ e in terp reta tio n an d to refutation. Even w hen seem ingly decisive attacks occur, they are apt to take place only after the individual has h ad considerable o p p o rtu n ity to process new evidence in the light of his beliefs an d som etim es even to reinforce his beliefs w ith consonant behavior. 251

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P erhaps the m ost im p o rtan t of the ecologically u n rep resen tativ e advantages enjoyed by the laboratory subject is th at experim enters typically m ake it explicitly clear th at they are soliciting inferences or ju d g m en ts from the subject. In everyday life, m an y inferential errors m ight be elim inated, or at least reduced, if the ‘4subjects” were to recognize explicitly that they w ere, in fact, engaged in m aking an inference. T h e individual who hears a cocktail p arty anecdote about an autom otive lem on, or sees a volcano while on vacation, or passes an able-bodied individual sitting on a p ark bench in m idday, is not told: “ H ere is some evidence. N ow answ er the following questions ab o u t the conclusions that can be d raw n on the basis of such ev id en ce.” B ut m any laboratory procedures go even fu rth er th a n th at in coaxing subjects to be on their best inferential behavior. Subjects are explicitly told th at the ex p erim en t is a test of inferential or ju d g m en tal skills. O u r greatest im patience w ith those who suggest th at system atic inferential failings are restricted to exotic lab o rato ry contexts stem s from the regularity w ith which everyday experience seem ingly parallels the relev an t laboratory findings. P resid en t L yndon J o h n so n led his co u n try into a futile w ar by evoking p otent social schem as of M unich-like cap itu latio n , falling dom inoes, aggressive foreign hordes, and bullies who h ad to be ta u g h t a lesson. Every day, people m ake harm fu l and d am ag in g ju d g m e n ts ab o u t them selves, or harm ful ju d g m en ts about their spouses even to the p o in t of severing m arriages, because they w rongly attrib u te c u rre n t crises to stable personal dispositions instead of to tran sien t situational pressures. D eserving jo b candidates are daily denied jo b s by personnel m an ag ers (an d university com m ittees) who see no reason to do ub t th at the vivid d ata p rovided by thirty-m inute personal interview s an d stress-laden “ jo b talk s” reveal new truths th at w ere som ehow obscured in pallid resum es, test scores, or letters of recom m endation. C ivic and state leaders regularly refute charges of police brutality or deplorable prison conditions on the basis of their “ sam p les” of police behavior or their personal tours of penal institutions. B etw een the Age of E nlighten m en t and the m iddle of the n in eteen th cen tu ry , th o u san d s and perhaps millions of people died at the hands of physicians whose opportunities to witness em pirical covariations betw een treatm en ts an d outcom es did not destroy th eir confidence in the th erap eu tic effects of such practices as blood-letting. As the tw entieth cen tu ry begins to draw to a close, intelligent people m ake a m ultim illion-dollar industry of astrology an d fill the pockets of quacks and self-styled gurus w ho prom ise to cure m edical, personal, or social ills. People, in short, do not suddenly assum e a m antle of credulity or ignorance when they walk into the laboratory. O n the co n trary , th ere is reason to believe that they w ear th eir S unday best w hen they en ter the psychologist’s sanctum .

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Finally, we wish to stress two ad ditional points concerning generalizability from the lab o rato ry to everyday life. M an y of the laboratory studies have been replicated in non -lab o rato ry contexts and in settings w here subjects did not even know th at they w ere particip an ts in an experim ent. T his is tru e both for m any studies in the a ttrib u tio n trad itio n and for m any studies in the ju d g m en t trad itio n . Som etim es it is children who are the subjects, taking p art in w hat they believe to be stan d ard classroom activities; som etim es it is expert professionals who are the subjects (for exam ple, in the C h a p m a n s’ w ork), innocently giving the investigator w hat they believe to be sim ply “ in fo rm atio n ” ab o u t th eir professional practices or inferential strategies; and som etim es the subjects are the stan d ard college sophom ores, b u t particip atin g in w hat they believe to be a test not of them selves b u t of som e new psychological instrum en t or institu tio n al p rocedure. In such cases, one is generalizing n o t from the laboratory to everyday life, b u t from one slice of everyday life to another. W e are often confronted w ith the suggestion th at results from studies like those discussed in this book m ight be quite different if subjects were paid for ju d g m e n ta l accuracy, the im plication being th at subjects care so little about th eir perform ance in the inferential tasks presented to them th at they give slipshod, off-the-cuff answ ers. T h e suggestion never ceases to surprise us, especially w hen it com es, as we m ust ad m it it often does, from o u r fellow professional psychologists. It m akes us w onder if such psychologists have ever chatted w ith th eir ow n subjects ab o u t their experim ents an d th eir subjects’ reactions to them . As we have ju s t arg u ed , we Find th a t o u r subjects take their particip atio n very seriously indeed and care a g reat deal ab o u t the sensibleness of their responses, so m uch so th at it w ould never have occurred to us to attem p t to im prove subject perform ance by m o n etary incentives. N evertheless, we have occasionally offered such incentives, an d so have K ah n em a n and T versky an d m any o ther investigators, in ord er to be able to confront skeptics w ith som ething m ore convincing th an gasps and arm -w aving. In general, incentives for accuracy produce no system atic effect on accuracy. Such incentives som etim es cause ju d g m en ts to change in such a way as to m axim ize subjects’ expected payoff, b u t even this effect is the exception. Subjects call it as they see it, an d m oney does n o t seem to m uch affect their eyesight. A lthough we vehem ently dispute the suggestion th a t serious inferential errors are restricted to the lab o rato ry , we can n o t deny th at readers could have been m isled som ew hat by the em phasis of earlier chapters. W e h ap p en to share the critic’s view th at people m ay not m ake as m any inferential errors as one m ight assum e from a sim ple list of the inferential failings that have been d em o n strated . In fact, som e critics m ight be surprised by how m uch we are willing to concede: W e believe it is possible th a t m ost people m ay get th ro u g h m ost of

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their days w ithout m aking any m ajor inferential errors leading to u n to w ard behavioral consequences. T his concession is not very reassuring, since it takes only a few such errors to seriously d isrupt individual an d collective social existence. But if, as we suspect, inferential errors of m ajor consequence are relatively infrequent in everyday life, it is w orth considering w hat it is that protects the intuitive scientist from paying the potential costs of his shortcom ings. W e focus on four such potentially m itigating factors: (a) intuitive strategies m ay typically serve us fairly well even w hen they are, strictly speaking, norm atively in appropriate; (b) m any of the m ost im p o rtan t inferences are collective, an d the errors of the group m ay be prevented by a single person; (c) different shortcom ings m ay som etim es cancel each other out; and (d) the behavioral consequences of erroneous ju d g m en ts typically m ay be m uted. W e wish to m ake it clear at the outset of our discussion that we are in no way recanting o u r belief that people regularly m ake serious inferential erro rs and that they som etim es pay very d ear for these errors. W e m erely wish to assert that there m ay be a good m any factors at work that serve to lim it the dam age and that m ay even operate in such a way as to encourage the survival of nonoptim al inferential strategies.

W HEN

IN T U IT IV E

S T R A T E G IE S S E R V E U S W E L L

As we have em phasized at m any ju n c tu res, o u r everyday or ‘ ‘in tu itiv e ” strategies serve us well in m any ju d g m en tal contexts. T h e availability heuristic does help us form accurate estim ates of frequency or likelihood in m any dom ains, that is, in those dom ains in which the perceptual or m em orial salience of objects or events is not distorted by factors irrelevant to the probability of their occurrence. T h e availability heuristic helps us to ju d g e , accurately and im m ediately, that there are m ore C hinese restau ran ts in Palo Alto than in A nn A rbor (we rem em ber seeing m ore), an d that the new A lbanian restau ran t in the suburbs is m ore likely to go b an k ru p t than the new M cD onalds in the shopping plaza (we can m ore readily construct a scenario for failure). Sim ilarly, the representativeness heuristic, for all the ju d g m en tal folly it can inspire, is a pro m p t an d faithful servant in a great m any dom ains, particularly where objects or events are characterized by properties that are both unique and invariant. T h u s, we do not confuse oak trees w ith telephone poles, or A nglican bishops w ith door-to-door salesm en. A nd people whose business it is to know about trees do not confuse oaks w ith m aples; nor do peopie whose business it is to know about prelates confuse bishops w ith abbots. O u r schem as and theories sim ilarly stand us in good stead m ost of the tim e. G eneric knowledge typically is well fo u n d ed — in som eone else’s ex­

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2 55

perience even if not always in o u r o w n— an d it norm ally serves as an autom atic guide to effective behavior. T his is particularly true in the m any cases in which events and event sequences are simple and in v arian t. T h u s we all learn early, an d seldom need to be rem inded, that switches tu rn on lights, an d hot things b u rn . Even relationships th at are only n ear in v arian t (for exam ple, transgressing the rules of pow erful people results in p u n ish m en t if the transgression is discovered; apologies and soft answ ers tu rn away w rath) are readily learned by observation or instruction and m ay serve as near-infallible guides for behavior. Ás we have em phasized, heuristics and know ledge structures do som etim es lead people astray w hen they are overextended or m isapplied. E ven then, the resulting errors often are inconsequential an d are readily forgiven by those w ith w hom we interact. R arely is it the case in social dealings th at a “ miss is as good as a m ile .” If we tem porarily m istake a bishop for an abbot, or for that m a tter an engineer for a lib rarian , there are few social consequences. W h en there would be consequences— if we started asking the en gineer ab o u t the D ew ey decim al system for classifying books— we usually have o u r e rro r quickly pointed out to us. T h u s, as we have em phasized at m any points, p eople’s intuitive inferential strategies are probably used ap propriately and effectively in the great m ajo rity of cases. In m an y cases w here they are not strictly ap p ro p riate, they m ay nevertheless yield answ ers th a t are sim ilar or identical to those th at w ould be produced by m ore ap p ro p riate strategies. A nd in m any of the rem ain in g cases, w here answ ers are in fact w rong, en vironm ental feedback m ay force a ready revision. Finally, the “ cost” of intuitive strategies is generally so low, relative to th a t of m ore form al strategies, th a t it seems distinctly possible th a t the long range “ econom ics” of their h abitual, preferential use is well in balance, even allow ing for fairly high frequency, in absolute if not in relative term s, of th eir disadvantageous consequences.

W H E N IG N O R A N C E O F N O R M A T IV E R U L E S M A Y C O ST U S L IT T L E

As we often have stressed, ignorance of the norm ative rules of inference can result in gross an d painful erro rs, small erro rs, or no errors at all, depending on the n atu re of the ju d g m e n t. It m ight be useful, how ever, to speculate a b o u t w hich no rm ative rules generally can be ignored with little cost and w hich cannot. C o n sid eratio n s of space p ro h ib it us from u n d ertak in g a full review of all the n o rm ative rules discussed in the book. W e shall restrict ourselves to th re e — one rule, th a t of the law of large n u m b ers, for which we suspect people m ay pay a surprisingly low cost for ignorance; one rule,

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nam ely the req u irem en t of ran d o m or unbiased sam ples, for which we suspect the cost of ignorance m ay be distressingly high, and one rule, nam ely the req u irem en t to revert to base rate or central tendency w hen highly diagnostic target inform ation is lacking, for which the questions ab o u t costs are com plex and difficult to resolve b u t also highly illum inating.

Sam ple Size

People have little u n d erstan d in g of the relationship betw een the size of a sam ple and its faithfulness in reflecting the characteristics of the p o pulation from which it was draw n. For certain sophisticated problem s of statistical inference this ignorance can be fatal, b u t in a great m any everyday contexts it m ay be far less costly than the form al statistician m ight im agine. C onsider the case of a stu d en t w ho m ust m ake course selections for the com ing sem ester and who wishes to consult a sam ple of past stu d en t evaluations. F or the sake of sim plicity let us assum e: a) th at some p ro p o rtio n (P) of the relevant population liked the course “ b etter than av erag e’ ’ while the re ‫־‬ m ainder (1 -P ) liked it “ less th an av erag e” ; b) that the stu d e n t’s objective is to select a given course if, and only if, the majority of the population liked it “ b etter than averag e” ; and (c) th at the probability that the student in question personally will like a given course is identical to the population proportion who like the course. F igure 11.1 sum m arizes the consequences o f four different decision strategies that the student m ight consider adopting. T h e first strategy is choosing or rejecting a course w ithout regard to any sam ple of peer opinion at all, th at is, ju s t flipping a coin and taking the course if the coin shows “ h ead s” and not taking it if the coin shows “ ta ils.” T h e second strategy is consulting a single, random ly sam pled stu d en t and taking the course if the student liked it, and not taking it if the stu d en t d id n ’t like it. T h e th ird strategy is a bit m ore com plex b u t it m ay offer a good appro x im atio n of the way m any people actually w ould o perate in the course selection problem . It consists of consulting two students and taking the course if both liked it, not taking the course if neither liked it, and sam pling a third an d decisive case (a “ tieb reak er” ) if the first two d isag ree d .1 T h e fourth strategy is the conservative (and costly) extrem e of sam pling the entire p o p u lation and then taking or not taking the course depen d in g on the m ajority evaluation. T h e left portion o f each panel in F igure 11.1 presents the degree of “ norm ative correctness” o f the decisions th a t w ould result from these fo u r 1 1 This “ two cases plus tiebreaker” strategy is essentially equivalent to that of sampling three cases (in which no “ tie” is possible), except that the former strategy specifies that the effort and expense of a third case be avoided when the first two cases have agreed and hence have already determined one’s decision.

p 1 ‫ —־־‬--------------- Certainty

Chance

S T R A T E G Y KEY ‫נ ם‬

Sample no data: chance, coin flip , etc.

777, Sample single case

Fig. 11.1

H

\

Sample tw o cases, plus tie breaker if necessary ~ I Sample all data: i.e., total

available population

Probabilities associated with normatively correct decision (DECISION)

and personally advantageous outcome (OUTCOME): A comparison of four sampling strategies across varying population proportions (P). 25 7

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strategies (that is, the likelihood th at the student will, as a result of using the strategy, take a course th at the m ajority likes or avoid a course w hich the ma* jo rity dislikes). It is im m ediately clear th at the strategies of consulting a “ single case” or consulting “ two cases plus a tieb reak er” fare qu ite badly w hen P is n ear .5, b u t serve quite well w hen P approaches u n ity (or zero). In other w ords, if there is high consensus ab o u t the course, the strategy of asking one student, or asking two students plus a tiebreaker w hen necessary, generally leads to norm atively correct decisions. For exam ple, if 80 p ercen t of the previous students liked (or disliked) the course, the strategy o f sam pling a single case rath er than relying on a coin flip increases the probability of a norm atively correct decision all the way from .5 to .8; the strategy of sam pling two cases an d a tiebreaker raises it alm ost to .9. A ny additional sam pling the student could do, up to the extrem e of sam pling all previous students, could only raise the likelihood of a correct decision from .9 to 1.0. T h is p attern becom es even clearer w hen the population p ro p o rtio n shifts from .8 to .9. Now, inform al sam pling strategies becom e overw helm ingly attractive. In fact, the likelihood of m aking an incorrect decision w ith the “ two plus tieb reak er” strategy is .03, low er th an the .05 level beloved by social scientists. O n the other hand, if only 60 percent of the p o p u lation of form er students liked or disliked the course, the use of a single case or even two or three cases w ould do the prospective stu d en t little good. S am pling a single case instead of relying on chance w ould only raise the likelihood of a norm atively correct decision from .5 to .6, an d the “ two plus tie b re a k e r” strategy w ould raise it only to .65. T h e outcom es sum m arized so far are m erely a specific d em o n stratio n of w hat every statistician knows ab o u t the relationship betw een “ p o w er” an d sam ple size. S trong statistical differences or “ effects” are revealed in small samples b u t w eak ones generally are not. If a social scientist w anted to know definitely w hether the m ajority of the students liked a co u rse— th at is, if he w anted to be certain before deciding u p o n a hypothesis th at pred icted P to be greater than .5— he w ould be incom petent indeed if he used the “ one case” or “ two cases plus tieb reak er” strategy and thereby ran a high risk o f failing to detect small b u t real “ effects.” But our s tu d e n t’s concern is not sim ply to m ake norm atively correct decisions. W hat the student w ants is to m axim ize the likelihood of personally advantageous outcom es. T h a t is, the stu d en t wishes to know the im pact of each of the four sam pling strategies on the chances of the decision leading to one of the two desirable outcom es— taking a course th a t he will like or avoiding a course he w ould have disliked. T h e right portion of each panel of Figure 11.1 presents the likelihoods of actually obtainin g a desired outcom e, and they can be su m m arized quite suecinctly. L arge samples never prove to be very helpful. W h en there is high consensus, small samples do alm ost as good a jo b of optim izing personal o u t­

Assessing the Damage

25 9

com es as very large sam ples do. W hen there is low consensus, small samples are of little value, b u t u n d er such conditions large samples also are of little value. T h e reason for this is sim ply that w hen the population has a fairly even division of opinion, a norm atively correct decision offers little likely advantage over an incorrect o n e .2* O n e particu lar 4‘extrem e case” deserves special m ention. W hen there is virtually total consensus (or, m ore generally, w henever one samples from a population that has virtually no variability), the sam pling of a single case is trem endously helpful. T h u s the traveler benefits enorm ously w hen he asks directions from a single local resident rath e r than relying upon a “ coin flip.” Sim ilarly, the curious individual who wishes to know the n u m b er of teeth in a h o rse’s m o u th , and wishes to do so w ith data rath er th an guesswork or logical deduction, will be served very well by “ sam p lin g ” a single horse. O u r suspicion is that people behave very m uch as the im plications of our extended exam ple would dictate. W h en in doubt about a course of action for w hich d ata m ight be helpful, one generally sam ples a case, or two, or even three w hen the first two cases disagree. W h eth er one consults a second case after sam pling a first depends on p rio r expectations of the degree of variability to be found am o n g sam pled cases. W e should not forget that people’s decision-m aking strategies are sometim es confidently based on d ata sam ples that are even less probative, and “ sm aller” even th an the TV of 1 in the “ sam ple one case” strategy above: S tudents som etim es select a course not on the advice of a friend who has attended it th ro u g h an entire term but on the basis of a frien d ’s “ sam ple” of the first day of class; an d people som etim es confidently infer on the basis of a five-m inute conversation at a p arty th at, despite h er rep u tatio n , J a n e is a bore. W e therefore should not lose sight of the fact that reliance u p o n very small sam ples is som etim es not a reasonable strategy. If the same behavioral choice is to be faced m any tim es, or if the cost of errors is likely to be comp o u n d ed , the effort or expense involved in securing large samples m ay well be justified. If statistics based on large samples are available at no ex tra cost, they are surely preferable to single cases or statistics based on m ore lim ited 2 Note that the probability associated with personally advantageous outcomes represents the sum of two products; it is the probability of the student deciding to take the course times the probability he would like it, p l u s the probability of the student deciding not to take it times the probability he would not like it. Consider, for example, the case in which P = .8, and the sampling strategy requires the sampling of two students plus a “ tiebreaker” if necessary. A personally advantageous outcome results e ith e r if the student’s sampling strategy leads him to the normatively correct decision to take the course [P = .82 + 2(.8)2(.2) = .896] and he then finds himself in the majority that likes it (P = .8), o r if his strategy leads to the normatively incorrect decision to avoid the course (P = .22 + 2(.8)(.2)2 = .104) but he nevertheless is in the minority that would have disliked the course (P = .2); that is, the probability of a personally advantageous outcome in this instance is (.896)(.8) -1- (.104)(.2) = .738.

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samples. If we are interested in the relative prices of fo u r-bedroom houses in com parable Palo Alto and A nn A rb o r neighborhoods, or if we w ant to know the size of fully grow n G reat D anes, or if we w ant to choose betw een the W estern at the R oxy or the com edy at the Bijou, we will pro b ab ly be as accurate as we need to be if we sim ply consult a couple of new hom e buyers, dog ow ners, or m ovie goers. But if we w ant to operate m ortgage or in su ran ce com panies, or if the costs of a w rong ju d g m e n t are very great, we had b etter continue to heed the advice of the form al statistician. Even if o u r interests are lim ited to a single, less-than-urgently im p o rtan t decision, we ought to use the best d ata that are freely available to us. T h e question of w hat constitutes the “ b e st” d ata available goes beyond the issue of sam ple size to that of sam ple bias. H ence, our next topic.

Sample Bias

A lthough the dam age resulting from faith in small d ata sam ples often m ay be both lim ited in m ag n itu d e and ju stified by the savings in effort, the case seems quite different w hen we tu rn o u r atten tio n to the question of faith in biased data. H ere, ignorance or credulity can have serious costs, even though, as we shall see, people are not w ithout defenses. C h ap ter 4 exam ined the laboratory evidence showing people’s insensitivity to the perils of biased data. W e should like to supplem ent this evidence w ith some ad d itio n al, anecdotal exam ples. T h e A nn A rb o r au th o r of the p resent book h ad been eatin g in an excellent restau ran t in Palo Alto w ith the Palo Alto au th o r of the book. “ A las” (or some sim ilar expression of dism ay), said the A n n A rbor au th o r, “ am ong all the other advantages of N o rth ern C alifornia over S o u th ern M ichigan, it hardly seems fair for y our restau ran ts also to be so m uch b e tte r.” “ W h at do you m e an ?” retorted the Palo Alto au th o r, “ I ’ve yet to get a b ad or overpriced m eal in A nn A rbor, an d let m e assure you I ’ve had plenty of bo th in Palo A lto .” Both au th o rs then m used abo u t th eir disagreem ent, each searching for the source of his colleague’s m isperception. C lever scientists that they are, it took the authors only a few m inutes to solve the m ystery of the discrep an t perceptions: Each au th o r h ad qu ite deliberately, as befits a host, presented the other w ith a sam ple of local restau ra n ts th a t w as extrem ely biased w ith respect to quality and price. T o u rists in large cities often have a related, b u t opposite, experience. T h ey sam ple eateries at ra n d o m — or w orse, they sam ple tourist traps at ra n d o m — an d then conclude th a t the re sta u ra n t situation in th at city is terrible, far inferior to th at in their own tow ns w here one can get a good, reasonably priced m eal “ ju s t by going to L u ig i’s” or “ ju s t by driving to that little out-of-the-w ay place on Busby B o u le v ard .” O u r real-w orld exam ples of susceptibility to biased d ata could be m ultiplied indefinitely. T h e bachelor an d the m arried m an w ho each feel u n ­

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due envy because of the “ d ata sam ples” th at each m akes available to (or hides from ) the o ther, is one fam iliar exam ple. T h e two m others, each of w hom is surprised to h ear h er own child described by the other as an obedient an d cooperative little angel instead of a q uarrelsom e little savage (because each sam ples “ h o m e ” beh av io r of her own child b u t “ v isitin g ” behavior of the o ther child) offer an o th er exam ple. In sum , for the case of sam ple bias, unlike th at of sam ple size, it is not difficult to cite real-w orld exam ples o f inferential errors that have nontrivial consequences. T h e source of the errors, m oreover, can be extrem ely difficult to track dow n, even for the form ally-trained scientist. T h e conclusion should n ot be overstated, how ever. A little thought suggests th at people som etim es have healthy defenses against biased data.

P rotection A gainst M endacious or Self-Interested Inform ants

It seem s likely th at we are fairly well protected against presentations of biased evidence by the patently self-interested inform ant. Few people are likely to be enticed by the new b u tch er sh o p ’s offer to sell “ 100 pounds of beef at less th an wholesale prices” w hen the p ro p rieto r em erges from the back room w ith a lovely steak and says “ m ost of the m eat is already packed b u t this piece is pretty typical of w hat y o u ’ll find in yo u r 100 p o u n d o rd e r.” Similarly, few consum ers are willing to accept paid testim onials as accurate indicators o f the satisfaction one could expect from the use o f a given product or service. People seem also to have a healthy skepticism about statistics presented by politicians, gov ern m en t or industrial apologists, salespeople, and others w ho have an obvious m otive to persuade. “ Y ou can prove an y th in g w ith statistics” o r “ T h ere are lies, d am n lies, and statistics” are two po p u lar expressions o f such skepticism . People often seem to have, how ever, a b etter appreciation of the professional sp o k esm an ’s ability to pick and choose am ong statistics th a n of his ability to pick an d choose am ong concrete cases th at are su m m arized in such statistics. T h u s, the econom ic advisor who assures the country th at the seasonally adjusted unem p lo y m en t rate has decreased by tw o-tenths of a percentage point m ay be greeted w ith cynical eye rolling, b u t a T V new s item ab o u t a single aerospace w orker who has landed a good jo b after three m onths o f u n em p lo y m en t m ay renew m any view ers’ optim ism .

T he “ A typ ical S itu a tio n ” Script

T h e “ m endacious in fo rm a n t” script is p erh ap s the m ost general and fam iliar schem a w hich offers p ro tection to people, b u t there are m any others. M ost professors, for instance, have learned th at the sam ple o f behavior of­

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H um an Inference

fered by freshm an advisees in th eir first m eeting is not a ran d o m or representative one. If the stu d en t appears in articu late, indecisive, or even unintelligent, experienced advisors typically recognize th at the stu d e n t’s perform ance m ay be biased by his nervousness an d u n certain ty ab o u t the interaction. U nfo rtu n ately , as we noted earlier, m ost of these sam e professors are not sim ilarly experienced in dealing w ith jo b candidates. T h ey do not give the sam e benefit of the doubt to poor perform ances, or w ithhold enthusiasm in the case o f an unusually polished perform ance, w hen a new P h .D . presents a jo b talk. T h e problem partially m ay lie in the o p p o rtu n ity for su b seq u en t verification. O v er the years, scores of advisees have proved them selves far m ore sensible and talented th an the first interview m ight have suggested. J o b candidates who are not hired, how ever, disap p ear from im m ediate view, and if they do prove successful it is usually several years later, at w hich tim e their success can be attrib u ted to grow th and experience rath er th an to the very qualities th at were obscured in the jo b interview situation. T h u s, the m ere fact th a t a situation is atypical does not g u aran tee a recognition of this fact an d a consequent reluctance to take the d ata at face value. N evertheless, it seems clear th at atypicality is often recognized, especially w hen feedback occurs, an d some protection against bias therefore results.

T he “ D iscrepancy from E xp ectation s’‫ י‬Cue

T h ere are m any causal explanations or schem as on w hich people m ay draw w hen a p articular perform ance differs from expectations. If a w orldclass tennis cham pion loses in straight sets to an u n know n, if o n e ’s star pupil does m iserably on an exam , if a norm ally w itty and ch arm in g guest is m orose at o n e’s d in n er party, or if a great dancer perform s far below p ar, people do not norm ally accept the evidence at face value an d drastically revise th eir previous im pressions. Instead, they readily generate causal theories or scripts involving factors such as illness, personal problem s, or overw ork. W hat people seem to lack is a general vigilance ab o u t the possibility of biased data. A lthough they respond to unexpected outcom es by en tertain in g the possibility of sam pling bias, they do not en tertain such a possibility so readily for expected or n eu tral outcom es. A lthough they are sensitive to the fact that m otivated com m unicators m ay offer them biased sam ples, they are far less aw are th at quite disinterested people, w ith no p articu lar m otive or desire to m islead, m ay also present biased d ata. M an y role- an d situationspecific biases offer no salient cues ab o u t the distortions they produce in the available evidence. Finally, as m any of o u r exam ples an d m u ch of the research shows, people do not seem to realize th at th eir p articu lar niches in

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the universe m ay funnel u n rep resen tativ e evidence or inform ation to them in a th o u san d different dom ains. It is h ard to avoid the conclusion that people suffer a great deal from their failure to u n d erstan d the possibilities that exist for data bias, an d for their failure to u n d erstan d in general term s ju s t how m uch dam age can be done by such bias. T h e “ special p u rp o se’’ scripts and cues th at pro m p t recognition of bias seem to us to be m issing in m any if not m ost cases where the available d ata are sufficiently biased to g u aran tee erroneous inferences.

R eliance on Target Inform ation O ver Base Rates and Central T en d en cies

P eo p le’s inclination to ignore base rates an d central tendencies an d to focus alm ost exclusively on potentially diagnostic inform ation ab o u t the “ targ et case” is well d ocum ented. W h at is less clear is how costly this tendency m ight be and w hat degree of protection people m ight have against it.

E qual or U n k n ow n Base Rates

As we noted in chapter 2, the tendency to ignore base rates obviously is w ithout consequences w hen the base rates in question are roughly equal. T his is tru e for som e n atu ral categories; there are roughly equal n um bers of m en and w om en, F renchm en and E nglishm en, sociology professors and history professors. T h e tendency is also w ithout consequences w hen base rates are un k n o w n and u n o b tain ab le. But there are m any decisions for which the base rates in question are know n and do have predictive value. O n such occasions, it is folly to disreg ard the base rate. Som etim es one m ust decide on the relative weights that should be placed, respectively, on discouraging base-rate and encouraging target-case in form ation, or vice versa. Should the hot prospect for q u arte rb ack be given the huge bonus he seeks, w hich otherw ise could be used to b u y veteran perform ers of know n abilities, given that: a) in background an d app earan ce, he is the spitting im age of the erstw hile g reat Jo e N am ath , b u t b) a perusal of the records w ould show that only 10 percent of the “ prosp ects” who are signed to bonuses ever becom e m em bers of the startin g team ? Should H orace Snade, the convicted m u rd ere r who has served tw enty years of a life term be g ran ted parole given that: a) his crim e was a p articularly heinous one an d his prison record has been m arked by fights an d an uncooperative attitu d e tow ards guards, b u t b) 90 percent of paroled m u rd erers w ho have served as long as S nade have m ade a success of th eir paroles? It is to such dilem m as (an d to the m an y related p aram etric problem s in which the in ­

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dividual m ust recognize the need to m ake predictions that are app ro p riately “ regressed” tow ard the m ean) th at people are m ost vulnerable.

H igh ly D iagnostic Target Inform ation

T h ere is an im p o rtan t, special case in w hich in atten tio n to base rates or central tendencies has little practical significance. W hen in fo rm atio n ab o u t a target case is highly diagnostic, that is, w hen the covariation betw een target features and outcom e categories is virtually perfect, p eople’s overreliance on representativeness criteria m ay cost them very little. Even the subjects in K ah n e m a n ’s and T v ersk y ’s (1973) classic d em o n stratio n w ould have been safe in ignoring base rates for engineers versus lawyers if they h ad been told that one of the target cases w orked for a firm that designed co m p u ter circuits and displayed a b u m p er sticker on his car read in g “ Kiss m e, I ’m an en g in e e r.” T h e base rates w ould not be literally irrelevant to an exact determ ination of probabilities, even in such a case. In term s of the “ o d d s ,” the relative likelihood of engineer in such a case is m uch g reater if engineers are com m on than if they are u ncom m on in the relevant p o p ulation. But for practical purposes, the difference is betw een a very, very high likelihood an d virtual certainty— a difference that w ould generally m a tter little. Sim ilarly, if the correlation betw een two variables is .95, it will do little h arm if the individual m aking the prediction fails to be regressive at all— that is, unless his concern is testing an exact scientific hypothesis, or m aking an actuarial pred ictio n for insurance purposes, or some o th er prediction w here the m arg in al gains for precision are very great.

Causality and Concreteness

As we noted in chapter 7, there is good reason to believe th a t, even in the absence of a general sophisticated u n d erstan d in g of B ayes’ theorem or of regression phenom ena, people m ay be sensitive to base rates in m any specific contexts. W hen people can place a causal in terp reta tio n on the base rate, or w hen they have experienced the base rate concretely, they can m ake substantial use of it. Perhaps the great m ajority of problem s w hich are properly regarded as involving a contest betw een b ase-rate an d target-case inform ation are characterized by one or both of these factors. W h en three y ear old J e n nifer announces that she saw a tiger on the play g ro u n d , h er p arents will have a strong recognition, on grounds of concrete experience and w ell-founded causal theory, th at the base rate for tigers in the neighborhood can n o t be set aside in favor of th eir young in fo rm a n t’s testim ony, no m a tter how im passioned it m ay be.

Novel vs. Recurrent Decisions A n im p o rtan t im plication of the considerations above is th at, for m any ju d g m e n ts of a recu rren t n atu re, people m ay com e to appreciate the relevance of base rates, if not in general term s then at least in concrete, “ scrip ted ’’ term s w hich can allow effective use of the base rate. W ith enough im m ediate feedback, an d suitable conditions of presentation, people can show very fine sensitivity to base rate in form ation (cf. H am m o n d and others 1975). T h e m a n ag er of a professional athletic team , the g rad u ate student adviser, the horse b reeder, are all likely to com e to recognize that hot prospects often stum ble and dark horses som etim es take the lead. Sim ilarly, people whose jo b it is to m ake predictions about product sales, the w eather, or stock perform ance seem to reach a kind of hum ility or conservatism th at is functionally equivalent to regressiveness. T h e very tendencies of which we were critical in ch ap ter 8, for exam ple people’s pen ch an t for unchecked causal theorizing, m ay serve the purpose of g en eratin g m axim s and rules of th u m b th at are regressive in th eir force ( ‘ ‘T hese hot shots often get too m uch praise and atten tio n , and then they slack off and stop w orking as h a rd ” ). T h e range of circum stances in which people are seriously hobbled by their lack of a general appreciation of base-rate an d regression considerations m ay be relatively narrow . T hese circum stances m ay be sum m arized on the basis of the preceding discussion: (a) w hen the ju d g m en t is a novel one and the individual has had no concrete experience w ith the relevant base rates and no o p p o rtu n ity to generate causal theories about them , an d (b) w hen baserates are know n to be un eq u al an d target-case inform ation is not actually diagnostic. T h e n u m b e r of such occasions m ay be large in absolute term s but sufficiently small in relative term s to ren d er people’s ignorance of base-rate considerations less su rp risin g , and the resulting dam age less severe, than m ight be im plied by o u r discussion in earlier chapters.

And T h e R everend Bayes M ay H a v e T o G ive a L ittle G round T oo

T h e lay p erso n ’s failure to be a do ctrin aire Bayesian m ay in the n ear fu tu re seem to be even less of a m ystery than it does at the present tim e. T h e m a th em atician Shafer (1976) an d the m easu rem en t theorists K ran tz and M iyam oto (1980) recently have b eg u n to develop a norm ative theory of inference w hich seems able to handle the sam e range of problem s covered by Bayesian theory. It is beyond the scope of this book (not to m ention the competence of its authors) even to outline this theory. O n e of its central features, how ever, is its deliberate n o n u tilization (or heavy discounting) of the base rate in m any problem s w here the Bayesian insists on its full em ploym ent. 265

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As of the w riting of this book, it does not ap p ear that m uch if any of the K ahnem an-T versk y research or n o rm ativ e analysis of specific problem s w ould be called into question by this new non-B ayesian position. B ut it is imp o rtan t to note th at the Bayesian analysis of problem s q uite sim ilar to typical K ah n em an-T versk y problem s has been sharply criticized. It is also of great interest that the new, “ S h aferian ” theory appears to correspond m ore closely to intuitive principles and to actual lay inferential practice th a n does Bayesian theory.

INFERENCE AS A COLLECTIVE ENTERPRISE

Cultural T ransm ission o f K now ledge

T h ere are several senses in which people protect each o ther from the inferential errors to which they m ight otherw ise be prone. P erhaps the m ost imp o rtan t is that we all are the beneficiaries of a trem en d o u s a m o u n t of knowledge built up by past and p resent ‘‘e x p e r t s /’ cu ltu ral specialists operating in subfields of inquiry. M u ch of the know ledge th at is m ost im portant to survival and effective functioning does not req u ire original inferential w ork. C o rp o ratio n executives are not throw n upon th eir own resources for estim ating m ost of the p aram eters that play an im p o rtan t role in th eir decisions. T ourists need not try to estim ate for them selves the q u ality of restaurants from their external features, an d brow sers need not ju d g e books by their covers. People do not have to try to estim ate w hether they are in any danger from sm oking cigarettes by observing the illness and m ortality rates of their acquaintances. T h e fact that a certain am o u n t of culturally supplied in fo rm atio n is incorrect, or is erroneously applied, does not d etract from the fact that an enorm ous am ount of inferential w ork is done for us by o ther people who w ork at least with m ore inform ation than we have, an d often w ith n orm atively correct procedures of inference as well.

N ovel Inferences and Social “ Q uality C on trol”

N ovel or “ first-tim e” inferences in daily life are subject to social verification procedures in m uch the sam e way th at new scientific findings m ay be scrutinized by the scientific com m unity. T h e m ore public is the forum in which the inference is presented, the larg er is the n u m b e r of potential critics. T hese critics m ay possess know ledge or m ay be able to offer arg u m en ts th at either support or cast doubt on the inference/

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It w ould be extrem ely in teresting to know how m any of the inferential errors rep o rted in this book w ould survive intact after an open discussion am o n g groups of ten or twelve subjects. O u r guess is that m ost of the errors w ould at least be substantially reduced. Even if only one individual in the group were able to com e up w ith a norm atively correct answ er, providing that he could offer persuasive arg u m en ts in favor of it, the group w ould be likely to shift their answ ers in the norm atively correct direction. T h e evidence on group vs. individual problem -solving efficacy (e.g. Kelley & T h ib a u t, 1954; D avis, 1973; V in o k u r an d B urnstein, 1978) suggests that, in general, group solutions are superior to individual solutions, though this conclusion m ust be heavily qualified by n o tin g that the extra tim e taken by groups is som etim es not cost-effective, an d , even m ore im p ortantly, that for some problem s and som e group com positions, less accurate solutions m ay result from group than from individual problem -solving (see, for exam ple, J a n is & M an n 1977). It should not be taken for g ranted th at, for all the sorts of problem s discussed in this book, group discussion w ould serve to reduce errors; though it seems likely that it w ould do so for m ost.

Correctness versus C onsensus

It is im p o rtan t to note th a t, for m any beliefs an d inferences, it is probably as im p o rtan t that they be shared as that they be correct. H arm o n io u s social interactio n often m ay depend m ore on consensus about the w orld th an on accuracy. It does not really m a tter w hether both of us call a spade a spade or both of us call it a shovel or even a spoon, as long as each knows w hat the o th er m eans an d agrees to use the im plem ent in the sam e way. It is chastening to be rem in d ed how m uch h arm o n y is possible in closed, prim itive societies whose cosmologies are a patchw ork of figm ent and error. Even those societies w hich h a rb o r extrem ely erro n eo u s and dangerous assum ptions ab o u t causality (for exam ple, a belief in w itchcraft) m ay pay a surprisingly small price for their shared m isconceptions.

COM PENSATORY ERRORS

It seems distinctly possible th a t the effect of some erroneous inference processes m ay be com pensated for by o ther erroneous processes, so that the net result is m ore benign th an one m ight expect from the individual contributions to th at result. W e discussed one case of directly com pensating biases in chapter 7 in our discussion of the “ d ilution effect.” N isb ett an d his colleagues (N isb ett an d Z ukier, 1979; Z u k ier, 1979;

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N isbett and Lem ley, 1979), it will be recalled, showed th at w hen subjects are asked to m ake predictions ab o u t target cases based on a co m b in atio n of “ diagnostic” and “ no n d iag n o stic” inform ation about the targets, b o th types of inform ation tend to be used in a norm atively in ap p ro p riate fashion. T h e diagnostic inform ation is treated “ nonregressively” while the n o n d iag n o stk x inform ation is treated , in effect, as if it were diagnostic of “ av era g en ess.” T h e net result of these two opposing or com pensating errors often is a prediction that m im ics the one th at w ould result from the m ore ap p ro p riate strategy of ignoring the nondiagnostic inform ation an d trea tin g the diagnostic inform ation in a properly regressive fashion. O th er exam ples of directly com pensating errors m ay be cited. For instance, in dom ains where outcom es are due to some co m b in atio n of ability and opportunity , predictions about these outcom es are ap t to reflect the influence of both the “ fu ndam ental attrib u tio n e rro r” an d a version of the “ g am b ler’s fallacy.” T h e form er encourages people to assum e th at outcom es reflect stable dispositions of the actor an d hence th at fu tu re outcom es generally will resem ble past ones. T h e latter m akes individuals believe th a t the future somehow com pensates for u n u su al outcom e p attern s by reversing those patterns ( “ J o e has been riding high, b u t he is surely h ead in g for a fall,” or “ A fter all that Sally has been th ro u g h , she is due for a few good b re a k s .” ) T ak en together, the net effect of these two biases m ay be the em inently reasonable prediction that an a cto r’s fu tu re outcom es will resem ble his past outcom es, b u t be less extrem e. T h e assum ption that errors m ay cancel each o ther out, th at two inferential w rongs m iraculously produce an inferential right, m ay seem P anglossian and facile, and we are reluctant to press the point w ithout m ore specific evidence. Less facile perhaps, is the m ore general an d essentially statistical argum ent that if a reasonably large n u m b er of in d ep en d en t biases o perate, the net erro r that results is bo u n d to be less th an the sum o f th eir individual effects. It m ay be the case that two erroneous b u t co untervailing inferential rules m ay be invoked by the sam e problem features often enough that the im pact of any given erroneous rule is softened considerably. It is even possible th at some erroneous inferential rules are reinforced by feedback or experience precisely because they habitually com bat the consequences of others. P articu lar inferential shortcom ings m ay be n eu tralized and m ay therefore survive if they typically occur in contexts in w hich there are com pensatory biases. P erhaps even m ore often, a given problem m ay trig g er two or m ore norm atively incorrect inferential procedures w hich produce two or m ore different conclusions. Such a conflict, in tu rn , m ay p ro m p t a m ore th o ro u g h an d norm atively approp riate inferential strategy, or referral of the problem to experts. It seems likely th at, in general, the m ore consequential the inference is, the m ore likely it is that such “ reserves” will be called u p in the event of conflicting ju d g m en ts.

INFERENCE AND BEH AVIO R

P erh ap s the m ost im p o rtan t source of protection from the errors produced by intuitive strategies is th a t ill-advised inferences do not necessarily result in ill-advised behavior. Som etim es, erroneous inferences m ay have no behavioral consequences o r m ay have consequences indistinguishable from those th a t w ould follow from correct inferences. Even w hen the behavioral consequences are different from those of correct inference, those consequences nevertheless m ay have equal or g reater utility.

Incorrect Inferences w ith N o B ehavioral Costs

It seem s clear th at m any inferences have no behavioral consequences or at any rate result only in inconsequential behavior. In fact, it seems likely th at this is tru e for the great m ajority of o u r beliefs and inferences, w hether correct or incorrect. Inferences ab o u t the relative frequency of m aple trees versus oak trees, or bishops versus abbots, or ab o u t the pro p o rtio n of unem ployed persons, blue-eyed persons, or an tiab o rtio n advocates, norm ally lack behavioral im plications for the actor. O nly seldom are people called upo n to act in accordance w ith beliefs ab o u t covariation, such as those concerning the tem peram ent of redheads o r the thriftiness of Scots. M an y erroneous inferences ab o u t causality also lack im p o rtan t behavioral im plications. O nly em perors and w ould-be sodom ites were ever likely to act on the belief th at sodom y causes earthquakes. T h e belief th at rain dances cause rain produces behavior no m ore dangerous than dancing in dry w eather (safer than, for instance, singing in the rain). In o u r discussions of peo p le’s beliefs ab o u t causality, we have stressed the pervasiveness of the fu n d am en tal attrib u tio n erro r. It is easy to see the personal an d social dam age th at can be produced w hen people act on th eir erroneous beliefs th at their insom nia, th eir m arital discord, or the unem ploym e n t of blacks is best u n d ersto o d in exclusively dispositional rath er than in situational term s. N evertheless, it seems clear that m any dispositional inferences have the sam e behavioral im plications as situational ones do. T h e decorous behavior of bankers, the au th o ritativ e m a n n er of doctors, and the av u n cu lar m a n n e r of clergym en m ay, perhaps, best be understood as the pro d u ct of certain role an d situational constraints. But behavior tow ard such individuals will be no less ap p ro p riate, in m ost instances, if people are guided by the erroneou s belief th a t the b eh av io r of such individuals is the p ro d u ct of u n d erly in g personality traits. M an y behaviors have the desired effects on the en v iro n m en t even though causal theories ab o u t the m ediation of the effects m ay be erroneous. For exam ple, m any effective ag ricu ltu ral an d m edical procedures are applied in 269

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the absence of a correct causal theory. M an y social or business strategies also are effective in spite of their origins in an incorrect theory. T h e general m anager who refuses to yield to the sensational rookie’s contract dem ands because he fears that such quick rew ards will p ro m p t com placency and a resulting sophom ore slum p, does ju st as well as one whose statistical knowledge suggests to him that second-year perform ances after exceptional firstyear perform ances will, on the average, regress som ew hat to the m ean.

Incorrect Inferences w ith R elatively D esirable C onsequences

It is perhaps a dangerous notion th at e rro r can som etim es result in m ore useful or desirable behavior than tru th can. Yet it seems clear that this is som etim es the case. A decision theory expert told us of an interesting d em o n stratio n he perform ed with the top executives of a large U .S . co rporation. H e described several potential new products to half of the executives and then asked them to rate their quality. H e described the same products to the o ther half of the executives and asked them to predict how well the products w ould do on the m arket. T he m arket success predictions perfectly m irro red the quality evaluations. T h en the executives were asked how well, in g e n e ra lone can predict m arket perform ance from product quality. “ O h ,” said the executives, “ you c a n ’t predict well at all. You can come u p w ith a terrific new p ro d u ct and the com petition can come up with the sam e thing 10 percent cheaper. O r you can tu rn out a lousy product th at somehow catches fire .” (For m ore form al dem onstrations of the same phenom enon, see T versky and K ah n em a n , 1978). T he concrete predictions of the executives showed the typical, nor!natively incorrect p attern of prediction, that is, a heavy use of the representativeness heuristic to the exclusion of regression considerations. T h e executives’ abstract generalizations about the relationship betw een p redictor variables and outcom es, in contrast, showed a norm atively correct u n d erstanding of the limits of predictability. C onsider the probable effect of the norm atively incorrect (that is, nonregressive) predictions in the case of a particular highly prom ising product. Will the behavioral consequences be untow ard? It is easy to im agine the “ disaster scenario” : U n d u ly im pressed by the excellence of the new product, the executives invest a huge p ro p o rtio n of the com pany’s resources in it. T h en the com petition does indeed produce the sam e product for less, and o u r first com pany is left h anging on the b rin k of bankruptcy. O n the other h an d , im agine that the executives act “ p ru d e n tly ,” on the basis of their norm atively correct u n d erstan d in g of the difficulty of predicting perform ance from quality. T h e com plem entary “ d isaste r” is perhaps equally easy to spell out: W ith insufficient resources invested in the

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p ro d u ct, its developm ent is delayed, and due to insufficient advertising, dissem ination of know ledge of its existence is retarded. T h e ‘‘im p ru d e n t’9 com petition, m eanw hile, rushes a sim ilar b u t inferior and m ore expensive pro d u ct to m arket w here it quickly catches fire and, because of m arket inertia, retains dom inance indefinitely. O u r original com pany loses out, an d pruden t executive heads roll. T h is p oint ab o u t prediction erro rs and b ehavior m ay be generalized: People som etim es m ay req u ire overly optim istic or overly pessim istic subjective probabilities to goad them into effective action or prevent them from taking dangerous actions. T h u s, it is far from clear that a bride and groom would be well advised to believe, on th eir w edding day, th a t the probability of their divorce is as high as .40. A baseball player w ith a b attin g average of .200 m ay not be best served, as he steps u p to bat, by the belief that the probability that he will get a hit is only .2. T h e social benefits of individually erroneous subjective probabilities m ay be great even w hen the individual pays a high price for the erro r. W e probably w ould have few novelists, actors, or scientists if all potential aspirants to these careers took action based on a norm atively justifiable subjective probability of success. W e also m ight have few new products, new m edical procedures, new political m ovem ents, or new scientific theories. W e do not w ish to dwell on the dangerous notion th at people’s actions m ay b etter be guided by erro r th an by tru th . Since we believe that the opposite is generally the case, o u r last ch ap ter is devoted to exploring the m eans by w hich people m ight be encouraged to ab an d o n norm atively incorrect inference procedures in favor of norm atively m ore correct ones.

SU M M A R Y

People m ay fare rath e r b etter in their everyday life than m ight be expected from a survey of lab o rato ry evidence or from the em phasis of this book. T his state of affairs does not reflect any in h eren t difficulties in the tasks studied in the laboratory. O n the co n trary , careful analysis suggests that the lab o rato ry tasks probably give the p articip an t ecologically unrep resen tativ e advantages. Instead, the everyday dam age from inferential shortcom ings is probably lim ited by several factors that have not been studied often in lab o rato ry settings. D espite their lack of “ rig o r,” intuitive strategies serve people quite well in m an y contexts. J u d g m e n ta l heuristics and know ledge structures are often well founded and helpful guides to inference. Ignorance of norm ative principles m ay have small costs for m any everyday inferential tasks, even if their costs are prohibitively large for m ore form al scientific ju d g m en ts. R eliance on

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very small sam ples, for instance, is a highly efficient or “ cost-effective” procedure for m any fam iliar tasks. R eliance on biased sam ples, by co ntrast, is a potentially lethal failing, although even here people are som etim es protected by dom ain-specific cues and by causal scripts. T h e potential costs of p eo p led general willingness to ignore base rates in favor of diagnostic in fo rm atio n , even diagnostic inform ation of un certain value, are sim ilarly lim ited by peop ie’s access to culturally tran sm itted or experientially based insights about particu lar phenom ena. Perhaps most im p o rtan t of the defenses is the collective n a tu re of m any inferential tasks. W iser, m ore experienced, o r m ore form ally train ed experts have passed on their insights and are often available to challenge the m ost blatant and m ost im p o rtan t of o u r erroneous inferences. In ad d ition, two or m ore heads, even nonexpert heads, are generally b etter than one, so the collective solving of problem s norm ally should produce inferences su p erio r to those of the individual w orking in isolation. It seems possible that peoples’ inferential shortcom ings m ay cancel each other out to some degree, and result in ju d g m en ts ap p ro x im atin g the outcom e of m ore norm atively correct procedures. Finally, the layperson is protected because erroneous inferences do not necessarily lead to m aladaptive b ehavior. O ften, incorrect ju d g m en ts have no behavioral im plications at all, and occasionally the costs of incorrect ju d g m en ts m ay be less th an the costs of m ore norm atively correct ones.

12 improving human inference: possibilities and limitations

Philosophical decisions are nothing but the reflections of common life, methodized and corrected, David Hume.

W e have identified a n u m b e r of shortcom ings in everyday inference— shortcom ings th at, for the most p art, can be traced either to people’s overreliance on prim itive ju d g m e n ta l heuristics or to their inattentiveness to conventional norm ative considerations. W e also have discussed some of the factors that m ay lim it the dam age done by such shortcom ings. Now it is time to supplem ent these diagnoses and prognoses w ith some discussion of ‘‘treatm e n t.” W hen should trea tm e n t be u n d ertak en and w hen should the patient sim ply be left alone? W h at can be done to reduce the incidence and seriousness of inferential m aladies? W hat factors m ake the therapeutic task m ore difficult? In the first section of the chapter we note some im p o rtan t differences b e‫־‬ tw een the prim arily “ a p p lied ” concerns of the layperson and the pure scientific concerns of the form al researcher, differences that cannot be ignored in assessing the norm ativeness of the lay p erso n ’s procedures. N ext, we discuss som e of the considerations that d eterm in e w hen it is advisable to substitute 27 3

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m ore form al inferential strategies for intuitive ones. W e then consider ed u ca‫״‬ tional techniques that m ight help to give the layperson a b etter u n d erstan d in g of those form al strategies an d of the logical or statistical principles that underlie them . Finally, we discuss som e of the b arriers th at fru strate efforts to im prove everyday h u m an inference.

T H E STA TU S OF T H E LA Y PER SO N : P U R E S C IE N T IS T O R A P P L IE D P R A C T IT IO N E R ?

T h ro u g h o u t the book we have held lay inferences up to the rigorous standards of form al scientific inquiry. In the p articu lar exam ples we have focused on, we believe that these stan d ard s w ere reasonable. As we first noted in chapter 4, how ever, only rarely does the layperson function in a role that is com pletely analogous to that of the pure scientist. T h e layperson is m ore nearly an applied scientist, and as such the n o rm ativ e rules g o verning form al inquiry in the pure sciences often are poorly suited to his purposes. T h e p u re scientist seeks to u n d erstan d the basis of lawfulness in the social o r physical w orld aro u n d him . H e is (or at least he should be) willing to m ake great sacrifices of tim e and energy in the interests of exactness an d certainty; for his is a collective endeavor lasting far longer than his own life, an d both the costs of his errors and the dividends realized on his insights are apt to be m ultiply com pounded. T h e applied scientist, by contrast, is concerned less w ith the u nderlying n atu re of reality th an w ith the pliability of the real w orld, less w ith discovering and u n d erstan d in g new p h en o m en a o r higher o rd er regularities th an w ith determ ining which p h en o m en a or regularities can be used in solving imm ediate practical problem s. T h e applied scientist whose jo b is to get a satellite in orbit aro u n d one of J u p ite r ’s m oons m ay know that the lack of a solution to the classic “ m an y -b o d y ” problem is m aking the task m ore difficult, b u t it scarcely follows from this that he should put aside his co m p u ter app ro x im ations to tackle the m any-body problem . By the sam e token, the in tuitive scientist whose im m ediate concerns are p redicting an d controlling o th er peop ie’s behavior can hardly aw ait, or personally try to b rin g ab o u t, the em ergence of a basic u n d erstan d in g of h u m an p ercep tio n , th in k in g , or m otivation. For the applied scientist, fu n d am en tal problem s are to be finessed, not solved; and fu n d am en tal inqu iry , w ith its exacting stan d ard s and dem ands, is an unaffordable luxury. It could be argued th at it is not even to the applied scientist that the layperson should be com pared, b u t rath e r to the p ractitio n er— to the physician, carp en ter, or w eather forecaster. U nlike the applied scientist, the practitioner norm ally does not invent solutions to problem s. In stead , he selects

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solutions w orked out by the m ost skilled and ingenious of the applied scientists who have preceded him . C ostly research to collect new data or invent new solutions will pay com m ensurate dividends only u n d er rath e r special circum stances. T h e goals of the inform al scientist often dictate procedures that would be highly co u n ter-n o rm ativ e for the form al one. W e have already noted one such instance of differing norm ative prescriptions in chapter 4. T h ere, we contended that the layperson, like any practitio n er using a prio r theory, b u t unlike the form al scientist intent on testing one, should allow the theory to govern the in terp retatio n of am biguous data. A thorough review of the differing goals of pure and applied science, and of the resulting differences in norm ative prescriptions, w ould take us far beyond the scope of this chapter and the com petence of the p resen t authors. O ne fu rth er exam ple, how ever, is w orth m en tio n in g because it so clearly points to the difference in priorities and strategies. W e noted in ch ap ter 4 how willing people seem to be to m ake inferences based on data they know to be biased. W e also noted th at it is often extrem ely difficult to d eterm ine the n atu re an d extent of the bias that exists in a given data sam ple or alternatively, to collect unbiased data. T h e conventional response of the form al scientist to such a state of affairs seems clear enough: m ove on to an o th er, m ore “ trac tab le” problem . But w hat of the layperson? T he req u irem en t of action in the real w orld (w here “ no actio n ” can be a highly costly “ resp o n se” ) is apt to p rohibit such a pristine stance. O ften , the layperson must proceed. H e can only hope that the inferential dam age w rought by an y potential bias is slight, an d try to m inim ize such dam age by avoiding u n d u e certainty. T h e req u irem en t of action is not the only difference betw een the d em ands placed on the p u re scientist and those placed on the lay practitioner. T h e layperson often m ust be guided by goals that are quite distant from issues of epistem ic correctness. T hese include the need to m ain tain com ity with o n e ’s fellows by sharing their perceptions of social reality, and a concern for fairness and justice. (F or a brillian t analysis of the com petition betw een epistem ic and extra-epistem ic considerations in the aren a of the law, see T rib e , 1971.) In short, it seems evident that any norm ative theory of lay inference m ust differ, even in its outlines, from the prescriptive theories th at guide scientific inference. Such a “ reg u lativ e” theory for the layperson (cf. G o ld m an , 1978), if and w hen it finally em erges, will und o u b ted ly contain principles th at capture the spirit of alm ost all form al principles of inference. But it will contain m uch m ore th a n those principles, an d the additional considerations will som etim es take precedence over the form al ones. It should be clear, therefore, th at in discussing ways of im proving lay inference it is not o u r intent to bind the layperson to the exclusive use of form al scientific rules and procedures. W e even think th at form al scientists are too

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often shackled by such procedures. F orm al inferential m ethods, as K u h n (1962) and others have noted, p rim arily serve the goals of verification and com m unication and suffice only for the conduct of so-called n o rm al science. T h e “ ru les” governing the m ore crucial tasks of hypothesis g eneration and discovery have not been developed; b u t we believe th at w hen they are, they will bear a strong family resem blance to the intuitive strategies o f the layperson (cf. Polanyi, 1958). O u r purpose therefore is less to proscribe the use of intuitive strategies than to foster a recognition of their lim its an d to enlarge the lay p erso n ’s repertoire to at least include the m ore form al strategies. W h eth er the individual will find it advisable to substitute form al strategies for inform al ones in a given instance, as we shall see, is a m a tter of relative costs an d benefits.

C O ST S A N D B E N E F IT S O F F O R M A L V S . IN T U IT IV E S T R A T E G IE S

M an y ju d g m en ts and decisions are so m anifestly trivial an d ro u tin e that no rational person w ould consider using an y th in g like form al inferential m ethods. C onsid er the b ehavior o f the person confronted w ith the list of thirty-six flavors in his neighborhood ice-cream parlor. H e m ay sim ply “ o rder w hat I always order, chocolate” or he m ay brow se th ro u g h the list in search of some flavor that meets some sufficiency criterio n or evokes some resonant chord ( “ T h e w om an before m e ordered B an an a N u t S u p rem e and she said ‘y u m ’ w hen she took h er first ta ste” or “ I ’m in the m ood for som ething totally new an d Tve never tried B oysenberry S u rp rise” or “ I love C oconut C ream Pie, so why n o t C o co n u t C ream S h e rb e rt.” ) If no flavor gains prim acy over its com petitors th rou g h such sim ple an d inform al procedures, the intuitive scientist m ay vacillate o r delay, typically feeling foolish at having tarried so long in so inconsequential a decision. But surely he will not, and should not, resort to m ore form al decision-m aking strategies such as polling a random sam ple of custom ers, in q u irin g ab o u t specific ingredients to determ ine w hether his schem a-based assum ptions are w arran ted , or assigning utilities and associated probabilities for each flavor. At the other extrem e, some decisions are so im p o rtan t th at exclusive use of purely intuitive strategies seems highly inadvisable. N orm ally, such decisions as w hat hom e or car to purchase, w hether o r not to change careers, or w hether to begin to raise a fam ily, should be u n d erta k en w ith the use of the best data and inferential strategies at o n e ’s disposal. (See W heeler and J a n is , 1980 for a lay-oriented guide to such “ vital d ecisio n -m ak in g ” ). Even for im-

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p o rta n t ju d g m e n ts, how ever, one should be loath to legislate blanket decision rules, as the following anecdote attests. O ne of the au th o rs recently found him self seated on an airplane next to the com ptroller of a m ajor U .S . corporation. T h e gentlem an was quite ch arm in g an d intelligent; that is to say, he in q u ired w ith ap p aren t interest about the a u th o r’s research activities. In the en suing conversation, the au th o r tro tted out his V olvo-Saab ch estn u t, add in g the hom ily th at, o f course, the n orm atively correct way to proceed in such a decision as a car purchase is to atten d chiefly to the opinions o f experts and to the distilled experience o f large n u m b ers of ow ners. “ N ot for m e ,” said the com ptroller. “ T h e way I buy a car is that I see a picture in, say U.S. News and World Report, an d then call up the dealer and o rd er one in green or blue or w hatever color I think I ’d lik e.” T h e au th o r stam m ered out som ething like “ to each his o w n ,” an d quickly changed the subject. O n reflection, how ever, the au th o r cam e to recognize the extent to w hich the executive’s simple ju d g m e n t procedure ( “ if it looks good, b u y it” ) faithfully reflected his priorities and expected utilities. F or the executive, in sharp contrast to the au th o r, the purchase price of a car is not a very serious cost. If the car proved unsatisfactory, it simply could be trad e d in at a loss of one or two th o u san d dollars (probably tax-deductible) for som ething else that caught his eye. H e w ould not miss the m oney, an d the tim e an d effort he spent replacing one car w ith an o th er w ould be m inim al; probably a phone call or in stru ctio n to a su b ordinate w ould suffice. U nlike the a u th o r, he certainly w ould not exhaust any tim e or patience, or engage in self-recrim inations, if the car tu rn ed out to be a “ le m o n .” T h ere also are cost-effectiveness considerations beyond tim e, m oney, and cognitive work. F or the com ptroller, a new car m ight be a sym bol of w ealth and status an d a source of pleasure. T o consult a host of facts and figures, to calculate m arginal benefits, probable fuel costs, and resale values, an d so on, m ight well d im inish th at pleasure. In fact, such activities m ight seem perilously close to those of his everyday professional life. T h e au th o r, by co n trast, does not (at least to his know ledge) derive m uch sym bolic satisfaction from the p urchase of an autom obile. B eyond furnishing anecdotal m aterial for his professional m usings, the car he drives is chiefly a m eans of conveyance and a potential d rain on his resources. In essence, he can “ affo rd ” to assum e a pinched-nose a c c o u n ta n t’s role w hen p u rchasing a car. In d eed , in view of the largely n o n p ecu n iary n atu re of his profession’s rew ards, and his ow n co m m itm en t to be as rational as possible in m aking imp o rtan t purchases, he can hard ly “ affo rd ” to do otherw ise. T h e relativity o f rational consum erism extends in both directions on the w ealth co n tin u u m , of course. T h e sam e au th o r recently confided to a g rad u ate studen t friend th a t, on a single w eekend, after consulting one expert an d doing a m in im al am o u n t of com parative shopping, he h ad decided to

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ju n k his old m alfunctioning stereo system and replace it w ith a far m ore expensive one. T h e student was aghast! ( “ D id you ever h ear the V olvo-Saab sto ry ,” she chided.) T h e au th o r had no shortage of defenses and excuses, mostly the difficulties and the m arginal advantages of trying to find the O ne Best Speaker System or the Ideal T u rn tab le. But the stereo anecdote makes exactly the same points as the car purchase anecdote does. T h e potential costs and utilities of following m ore norm atively ap p ro p riate decision strategies— in the m arketplace, but in other arenas as well— depend on the life situation, values, and resources of the decision-m aker. M ore generally, one should not lightly criticize or recom m end “ tre a tm e n t” for the seem ingly no nnorm ative character of a n o th e r’s ju d g m en ts. For the illness m ay often be m ore bearable for the individual— that is, offer a b etter ratio of benefits to costs— than the cure. In introducing the question o f cost-effectiveness, we have relied on consum er decisions for illustrative purposes because the costs and benefits of both form al and inform al decision strategies in such cases are apt to be readily discernible to the reader. T h e same issues obviously arise in nonco n su m er decisions or jud g m en ts. ( “ Shall I walk the dog before or after su p p e r? ” “ Shall I phone Fred and congratulate him on his prom otion or will he think I ’m trying to be in g ratiatin g ?” “ Shall I kiss J a n e goodnight or m ight she misin terp ret?” “ Should I drop out of the g raduate pro g ram in psychology and apply to law school?” ) In each case, the decision about w hether even to consider the relative m erits of m ore form al versus less form al decision strategies is apt to be dictated by the ap parent im portance or triviality of the benefits that m ight result from m ore form al inferential strategies. It should be em phasized that the costs of tim e and effort associated w ith relatively formal strategies for inference or decision-m aking are not always higher. Even beyond their potentially greater dividends, their cost som etim es m ay be quite a bit lower than the costs associated with intuitive strategies. For exam ple, the m echanical application of a simple regression form ula for student selection seems to achieve better results (in term s of traditional reliability and validity criteria) than the laborious intuitive m ethods applied by expert ju d g es and decision m akers (D awes, 1979). E ven if the sim ple form ula m erely equaled the perform ance of expert ju d g es, of course, it could be defended on grounds of cost alone. As Slovic (1976) and others have noted, even a very expensive “ sta rt-u p ” o peration (establishing em pirical regression w eights, and so on) can pay enorm ous dividends w hen recu rren t, conceptually identical decisions are m odeled form ally. K ah n em an and T versky (in press), as well as Slovic, have outlined some of the procedures that can greatly im prove these recurrent ju d g m en t tasks. Even n o n -recu rren t, u nique decisions som etim es can be m ade m ore efficiently with relatively form al strategies th an w ith the co m b in atio n of in tu itio n

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and inform al d a ta collection th at som etim es are b ro u g h t to b ear (often with accom panying obsession) in m aking im p o rtan t life choices. T his is particularly tru e w hen som e highly valid d ata are readily available, b u t vivid and nonprobative d ata ab o und. T h e decision about which college to atten d , or which c ar to purchase, are cases in point. O bjective inform ation com piled by experts is readily available and it is easy to review th at inform ation in light of o n e ’s priorities. T h e inform al op tio n s— carefully poring over brochures, discussing the m a tter ad n au seu m w ith o n e ’s friends and fam ily, m aking personal visits to see the various cars or cam puses with o n e ’s own eyes— are far m ore exh au stin g of o n e ’s resources and far m ore likely to m ake one the victim of happenstance, ill-founded advice, or the in g ratiatin g individual whose prim ary objective is to sell the prospective client. In considering the “ cost-effectiveness” of form al versus inform al strategies, it is im p o rtan t not to lose sight of costs and benefits that m ight be social or psychological, an d difficult to express in term s of tim e, m oney, or o th er econom ic desiderata. F or instance, the tasks of carefully com piling evidence, m aking decision criteria explicit, and so on, m ay be relatively pleasurable or esteem -enhancing for one individual and relatively noxious and ego-deflating for an o th er individual. T h e likelihood that one will be forced to justify o n e ’s decision to others, o r even to oneself, m ay tip the scales in favor o f a m ore form al strategy, even if o th er costs and benefits are relatively equal. O n the o th er h an d , the exclusive use of a cut and dried form u la for certain decisions, for exam ple, personnel decisions, m ight have costs— in term s of ap p earin g cold, rigid, and in h u m a n —th a t w ould offset gains in efficiency and validity, o r even in objectivity and fairness. O nly the decision m aker, m indful of p articu la r priorities and values, can assess the app ro p riate w eight to give such social and psychological factors. A final point about cost-effectiveness is that the sheer im portance of the outcom es that will follow from a decision is not a sufficient justification for costly inferential strategies, w hether form al or intuitive in n atu re. T h e gam e show contestant told to choose either the red box or the blue box, know ing only th at one box contains a $10,000 check and the o ther an old shoe, will profit little from form al inferential strategies. T h ere are some decisions that, although o f critical im portance, have outcom es that are unknow able in principie or that are presently indistinguishable in term s of th eir overall costs and benefits. In such cases, a flip o f the coin m ay be the m ost cost-effective strategy available. * O u r “ decision-theoretic” analysis of inform al versus form al strategies m akes it clear that the n o rm ativ e questions, as always, are m ore difficult th an first m eets the eye. W e cannot m a in tain th at people should always use m ore form al strategies, even for inferential problem s of great im portance. N evertheless, the present analysis indicates that people often are well advised to

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choose m ore form al strategies. Such choices can be m ade m ost rationally by people who enjoy a clearer u n d erstan d in g of the advantages of form al inferential strategies— an d of the m ajor failings of inform al strategies— th a n o u r educational system now provides.

P R O G R A M S T O IM P R O V E IN F E R E N T IA L S T R A T E G IE S

K now ledge of inferential principles an d failings, an d skill in applying th a t know ledge, does not g u aran tee correct inferences. But it can greatly reduce the likelihood of erro r in at least some dom ains of ju d g m e n t an d can reduce the likelihood at least m arginally in a great m any m ore. W e therefore consider it advisable to teach form al inferential principles to as wide a public as possible. T w o questions present them selves. F irst, how can the in fo rm atio n best be taught? Second, how effective are even the m ost energetic an d wellconceived attem pts at education likely to prove?

P recon dition s of Change

It seems im p o rtan t to establish a m ore receptive clim ate for the ed u ca‫־‬ tional un d ertak in g we advocate. People m ust be p ersu ad ed th a t they are prone to inferential errors that are highly recognizable an d codifiable. T h ey m ust be given greater m otivation to atten d closely to the n a tu re of the inferential tasks that they perform an d to the quality of their perform ance. T his book (following the lead of Newell an d Sim on, K ah n em a n an d T versky, Slovic and L ichtenstein, D aw es, an d others) has taken a step in this direction. A lthough we have addressed a narrow an d uncharacteristically sophisticated audience, the first retu rn s on o u r own efforts seem encouraging. W e have found that university students at all levels who are exposed to the m aterial in this book are stim ulated and intrigued. T h ey readily recognize them selves in o u r p o rtrait of the erro r-p ro n e intuitive scientist. D aniel K ah n e m a n , who has begun a program of education in inferential strategies an d shortcom ings directed at high school students, reports sim ilar experiences. In d eed , he suspects that his initial efforts m ay have been carried a bit too far, as m any of the students becam e so convinced of th eir inferential incapacity th at they despaired of m astering m ore ap p ro p riate techniques. O u r experience in this regard has been som ew hat sim ilar. It is easier to shock audiences into a recognition of th eir susceptibility to erro r or bias than it is to reassure them of their already form idable defenses an d their capacity for im p ro v em en t.

Teaching Statistics M an y of the inferential principles central to the education we are proposing can be appreciated fully only if one has been exposed to some elem entary statistics an d probability theory. (Som e exposure to research m ethodology and philosophy of science also w ould help.) P erhaps no subjects are m ore inap p ro p riately excluded from the curricula o f p rim ary an d secondary schools th an these. Som e fifty years ago, H . G. W ells expressed the opinion that it w ould shortly be recognized th at the teaching of statistics was as central to the production of an ed ucated citizenry as the teaching of reading and w riting. H e was w rong in his prediction, but that is to o u r discredit, not his. T h e present au th o rs lack the necessary b ackground or expertise to speculate about the best m ethods for in tro d u cin g school children to inferential problem s and concepts. But every course, from history an d civics to science or even to arith m etic, surely provides some o p p o rtu n ity for in tro d u cin g the concept of ‘‘biased d a ta ” an d the notion that o u r preconceptions structure an d potentially distort w hat we see, u n d erstan d , an d rem em ber. O ne logical place for exploring these concepts, an d m any m ore sophisticated ones (such as the existence an d n atu re of regression p henom ena), is w ithin the context of an in tro d u cto ry statistics course. In o u r opinion, elem entary statistics and probability theory should be in tro d u ced at least as early as secondary school. N eedless to say, we w ould advocate statistics courses geared less to significance testing an d other concerns of social science m ajors, an d m ore to everyday problem s of inform al inference and ju d g m e n t. In any case, statistics should be taugh t in conjunction w ith m aterial on intuitive strategies an d inferential erro r of the sort presented in this book. It seems to us that this would have the advantages both of clarifying the u n d erly in g principles of statistics an d probability an d of facilitating an appreciation of their applications to concrete ju d g m e n ta l tasks. W e are pleased to note that a statistics text em phasizing ju d g m e n ta l heuristics an d the contest betw een intuitive an d form al inferential strategies is cu rren tly being p rep ared by W . H . D um ouchel and D. H . K ran tz (1979) of the U niversity of M ichigan. W e are also pleased to rep o rt th at initial stu d en t response to th at approach seems very positive.

T ea ch in g by C oncrete Illustrations and V iv id A necdotes

W e have ch aracterized the intuitive scientist as being highly responsive to concrete, vivid, an d anecdotal inform ation. If this ch aracterizatio n is correct, it has clear im plications for educational strategy in general an d for ed u catin g people about inferential strategies an d shortcom ings in p articular. 281

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Because we believe this, we have loaded o u r book w ith such m aterial in the hope that it w ould m ake the ideas easier to co m p reh en d an d allow them to be generalized m ore readily to o ther concrete inferential tasks. W e have done so w ith no little trepidation about the degree to w hich we have exposed ourselves to the charge of exploiting, in o u r own arg u m en ts, the very shortcom ings against which we w arn o u r readers. W e believe that there is noth in g contradictory or hypocritical in o u r position. W e offer in o u r defense B rick m an ’s (1978) observation th at concrete, anecdotal m aterial is essential for com prehension (or, in B rick m an ’s term , for ‘‘phenom enological reality ’’) and that it is only the inferential or putatively evidential use of such inform ation that is dubious. T h e particu lar anecdotes and th o ught experim ents presented in this book, we should note, are not the best aids to com prehension and generalization for all constituencies. T h ey have been chosen specifically for an audience of social scientists an d academ icians, and probably will be of less value to other types of audiences. A decision-theory expert told us that in consulting w ith large corporations, he has learned to present exam ples and case histories that overlap as m uch as possible in their concrete elem ents w ith those th at the executives use in their own w ork, even if those concrete elem ents are ‘ ‘logically’ ’ irrelevant. H e recounted an experience of telling the executives of a com puter corporation about a problem faced by a ru b b e r com pany th a t was formally sim ilar to one confronting the co m p u ter executives. T h e response was a wadi of blank stares. A t last one executive replied u n com fortably, “ W ell, th a t’s the ru b b er in dustry, here we deal w ith c o m p u te rs.” Lest the read er decide th at corporation executives are u n usually pro n e to be victim ized by the representativeness heuristic, let us recall C olonel H o u se’s testim ony about P resident W oodrow W ilson, the ex-academ ic,w ho on the very eve of W orld W ar I was fretting ab o u t the possibility of w ar w ith England. H ouse reported that W ilson had this fear because the English w ere currently searching A m erican ships illegally ju st as they h ad before the W a r of 1812 and du rin g the presidency of Ja m e s M ad iso n , “ the only o th er P rin ceto n alu m n u s” to occupy the W hite H ouse. Illustrations both of inferential e rro r an d of correct applications of form al inferential strategies thus should be tailored to o n e ’s audience. By p resenting people with a large n u m b er of concrete exam ples draw n from th eir daily experiences, they ultim ately can be led to construct new know ledge stru ctu re s— schem as, scripts, stan d ard o p eratin g p ro ced u res,— an d the like that generalize and abstract the conceptual elem ents com m on to the exam ples.

M axim s and Slogans: T he Fortune C ookie D id actic

It is ap p are n t th at everyday inference is not governed by schem atized, concrete experience alone. Ju d g m e n ta l m axim s and slogans (a b ird in the hand. . .; a s the twig is b en t . . . an d so on) are so u b iq u ito u s th at they p ro b ­

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ably serve at least to com m unicate recom m ended strategies and perhaps even to guide the perform ance of p articu lar inferential tasks. W e have tried o u r hand at inventin g (and borrow ing from social science term inology) some useful slogans for didactic purposes. M an y of these were presented elsewhere in the book; others now are added that convey sim ilarly im p o rtan t messages. Since we are new to the business of sloganeering, m ost of o u r m axim s leave m uch to be desired from a literary standpoint. W e trust that this reflects only the a u th o rs’ lim itations and not any inherently greater difficulty in expressing tru th than in expressing half-truths or errors. It ’s an empirical question . T his is a slogan know n and used by most social scientists. It m eans m any things, all of which are likely to point those who use it in a helpful direction. Som etim es it m eans “ T his is a question whose resolution can be reached only by consulting or generating d a ta .” Som etim es it is the social scientist’s gentle rem in d er that one should place lim ited confidence in any theoretical proposition that lacks a sound em pirical footing, no m atter how plausible the proposition m ay seem on purely a priori grounds. For m ost social scientists, there is a solid groundw ork of professional experience behind this slogan, as so m any of society’s and of o n e’s own personal theories have tu rn ed out, in the crucible of em pirical test, to have no support. P erhaps that is why there are so few social scientists, at least of o u r acquaintance, who w ork constructively w ith d a ta and yet rem ain extrem e ideologues. T h e conduct o f social science research, like the p u rsu it of philosophical inquiry, is apt to m ake one tentative about all of o n e ’s social theories. W e have argued th a t people hold m any social theories th at are sim ply w rong, that they hold m any partially correct theories with too great confidence, that they often apply theories erroneously beyond their app ro p riate dom ains, and th at they often substitute a read-out of theory for an appraisal of d ata even w hen the relevant data can be obtained readily. T h u s we believe that the social scientist’s slogan “ I t ’s an em pirical q u estio n ” prom pts a needed corrective to the lay p erso n ’s natu ral confidence in theory. T h e slogan does not have the passion of L ord C ro m w ell’s cry, “ I beseech you, in the bowels of C h rist, think it possible you m ay be w ro n g .” But a thorough appreciation of the m ean in g of the slogan m ay result in a greater w illingness to question the certainty of o n e ’s views. W hich hat did you draw that sample out of ? It m ight be useful to have this slogan at o n e ’s fingertips for those occasions when questionably sam pled evidence is adduced in support of some proposition. T h u s, a reference to the characteristics of T ennessee W illiam s to support a proposition ab o u t hom osexuals, or a generalization about R ussians adduced from observations of B rezhnev or B aryshnikov, could im m ediately be challenged. T he slogan m ight also be useful to confront those who argue against uncongenial statistics w ith “ co u n terex am p le” cases. It seems likely to us that, with a minim um of form al statistical train in g , a thorough g ro u n d in g in the m ean in g of the slogan could bestow on the layperson one o f the inferential defenses o f the social scientist. By the sam e token, the layperson could readily be m ade to ap ­

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preciate the inferential pow er of data sam ples that are d raw n randomly. T h en , perhaps, fewer people would scoff at the G allup Poll that, on the basis of only a few h u ndred interview s, predicts defeat for their candidate. A nd, by und erstan d in g the “ h a t” slogan, they would take less com fort from the huge crowds shown cheering their candidate in the nightly news. O kay , what do the other three cells look like? F o r this slogan to m ake any sense, the h earer m ust be fam iliar with the logic of the 2 X 2 contingency table. In o u r opinion, this know ledge ought to be im p arted long before the college level. A lthough necessary, such abstract know ledge is insufficient to guarantee norm atively ap p ro p riate responses to covariation propositions. Social scientists usually are not as readily victim ized by d ata on the order of, “ W ell, I know lots of people who were cured of all sorts of things by ch iro p racto rs,” as laypeople are. But we find that even w ell-trained social scientists are apt to respond to such observations with a logically in ad eq u ate request for data from only one or two oth er cells ( “ Yes, b u t how ab o u t the people w ho d id n ’t get cu red ?” o r “ W hat about the people w ho got b etter w ithout tre a tm e n t? ” ) O u r slogan m ay not come trippingly off the tongue, b u t a m axim or rule of thum b is needed which makes it clear that there are indeed four separate observations that m ust be considered for even the sim plest case of covariation assessm ent. A gain, a n u m b e r of concrete and m em orable illustrations will be necessary to drive this point hom e an d increase the likelihood of its application to new cases. B eware of the fundamental attribution error . (O r, for a less hortatory tone: C onsider the a c to r’s situation before ju m p in g to conclusions about his dispositions). T h is slogan is not universally endorsed by social scientists. Instead, it has been a battle cry for one group of social scientists— an alliance of role-theory sociologists, behaviorists, an d ex p erim en tal social psychologists— challenging a second g ro u p — an alliance of psychodynamic psychologists and trait-theory personologists. (T he divisions, how ever, are not as simple as this implies. A brilliant psychodynam ic, b u t fundam entally situationist view of psychopathology and treatm en t possibilities, for exam ple, is offered in H aley ’s The Uncommon Therapy, 1973. B ehaviorism , on the other hand, can be, and in its early days often was, associated with a strong dispositionalist or “ individual difference” view point.) By now it is obvious to the reader that the situationist battle cry is o u r own and that we would like to hear it from the lips of the layperson as well. W e suspect, m oreover, that few of o u r colleagues, regardless of their theoretical cam p, would deny that the injunction often can provide the layperson w ith a useful perspective. It sanctions, m oreover, a n u m b e r of useful special-purpose m axim s that express the sam e u n d erly in g thought (“ W hat would you have done if you were in his shoes? or “ T h ere b u t for the grace of G od go I . ” ) Each of these m axim s points in the direction of role dem ands o r situational d eterm in an ts of behavior, an d each tacitly counsels

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against in ap p ro p riate dispositional in terp retatio n . In o u r experience, the b ro ad injunctio n adds som ething to the specific m axim s. It w arns against hasty behavior-based inferences ab o u t personal characteristics even for those cases in w hich the exact n atu re of the situational forces and constraints is not im m ediately ap p aren t. Y ou can always explain away the exceptions. In o u r experience, the layperson has difficulty recognizing that people’s explanatory pow ers are so keen, and the possibilities for alternative in terp retatio n are typically so rich and varied, that exceptions only seldom pose problem s for any general theory o r rule. Even the social scientist in the conduct of professional inquiry has far too little appreciatio n of this fact. It has only been in w riting this book, in fact, th a t the au th o rs have becom e at all self-conscious about explaining away exceptions to th eir favorite theories an d generalizations. T his m axim , or som ething like it, should help to w arn the scientist against too vigorous a defense of his pet theories, ju s t as it should caution the layperson who is guilty of the sam e offense. F urther inferential maxims and their generation. T he authors m ust resist the tem ptation to restate, this tim e in fortune-cookie fashion, all of the theses of the preceding chapters. A few m ore m axim s, how ever, are offered w ithout elaboratio n , in the hope that they will both jo g the re a d e r’s m em ory and encourage the g eneration of new er and b etter ones. M e th in ks I d e te c t the a v a ila b ility (or re p re se n ta tive n e ss) h e u ristic at w ork. T h a t’s a vivid d a tu m (or th a t’s a strik in g “ m a n -w h o ” sta tis tic ) all right, but I’ll still c o n s u lt the base rates, th a n k you. N o w look at the sa m e d a ta fro m the va n ta g e point of our th e o ry (or the ir th e o ry ), in s te a d o f y o u rs . Y o u ’re b o ls te rin g y o u r th e o ry w ith “ p ro c e s s e d in fo r m a tio n ” in s te a d o f “ ra w d a ta .” B e fo re c o n s id e rin g a fa n c y ca u sa l e x p lan a tion , h ow a bout c o n sid e rin g sim ple re g re ssio n ?

T h e au th o rs w ould love to see the g eneration of inferential m axim s becom e a p o pular diversion for epistem ologists an d social scientists. Brevity, ‘‘p u n c h in e ss,” and wit should be the chief desiderata. O n e simple technique we recom m end for w ould-be inferential epigram m atists is the inversion or qualification of p o p u lar (b u t norm atively suspect) m axim s already in the public dom ain. For exam ple: “ Y ou can lie w ith statistics, b u t a well-chosen exam ple does the jo b b e tte r.” T h ree fu rth er exam ples, designed to startle people into an appreciation of the regression p h en o m en o n , are offered below. (A nd let him w ho is w ithout doggerel cast the first b one.) As ye sow , so shall ye reap . . . but g e n e ra lly less so. As the tw ig is b e n t . . . so the tre e is s lig h tly and o c c a s io n a lly in cline d . N ine s titc h e s in tim e d o save, at least on a verag e , a s titc h or two.

O V E R C O M IN G T H E B A R R IE R S T O C H A N G E

T he preceding section tacitly conveys o u r conviction th at the quality of h u m an inferences and ju d g m en ts can be im proved. W ith o u t this conviction, ou r proposals for education w ould have little point. But how m uch im provem ent can be expected, even from the best of educational program s? T h e first answ er m ust be that we do not and cannot know; it is, indeed, “ an em pirical q u estio n .” A second, som ew hat less noncom m ital answ er, is th at we suspect that the possibilities for change, for p articu lar types of inferences in p articu la r dom ains, range from alm ost nil to very great. W e do not anticipate, for exam pie, m uch change in people’s susceptibility to the pow er of theories, an d oth er knowledge structures, to bias their in terp retatio n of events. M ost bias of this type is autom atic and reflexive, and we have arg u ed th at in any case such “ b ia s” generally prom otes rapid, efficient and correct coding of events. O nly rarely, we suspect, will people be able to separate the w heat am o n g their knowledge structures from the chaff. By the sam e token, we do not expect any real im provem ent in people’s ability to assess covariation. U n d e r m ost circum stances, this requires m ental operations that are sim ply beyond o u r intuitive, inform al capacities. A bout the most that can be expected in this area is that people can be m ade to recognize their incapacities an d to be dub io u s of any covariation theories th at are not based on the system atic collection an d analysis of appro p riate data. At the other extrem e, there are some inferences, in at least some dom ains, for w hich we expect that very great im p ro v em en t will prove possible. A general fam iliarity w ith the ideas in this book should provide people w ith substantial defenses against certain kinds of arg u m en tatio n based on m anifestly flawed evidence, or on dubious an d facile causal theories. A nd u n d erstan d in g of the general idea of regression should bestow sim ilar ad v an tages, at least u n d er circum stances w here people recognize explicitly that they are m aking predictions. T h e m agnitude of gains from each of these insights should at least approxim ate the gains attain ed from an u n d erstan d in g of the g am b ler’s fallacy or an appreciation of the distinction betw een d ep en d en t and independent events. O u r optim ism about the m agnitude of u ltim ate change is tem p ered by several factors. It seems to us th at there are several very general an d very serious barriers in the p ath to change. T o some extent these b arriers m ay lim it the degree of change to be expected in any area. T o some extent they m ay best be regarded as challenges that m ust be su rm o u n ted , o r at least sidestepped, if the most exciting prospects for change are to be realized. W e will speculate about three m ajor barriers: (a) o u r inability to directly observe o u r cognitive processes, (b) o u r susceptibility to inferential erro rs w hen con286

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fronted w ith particu larly vivid and personally-relevant inform ation, and (c) our general tendency to be overly confident about w hatever ju d g m en ts and inferences we have h appened to reach.

Inferences A bout O ur Inferences

A distressing lim it is placed on o u r ability to im prove o u r inferences by o u r lack of introspective insight or self aw areness. H av in g no w indow on our cognitive processes, we cannot sim ply note flaws and correct them in accordance w ith o u r no rm ativ e insights. In stead , we m ust infer indirectly, on the basis of spotty and im perfect evidence, w hat those processes are. As chapter 9 m ade clear, the opp o rtu n ities for self-delusion are legion. W e are likely to reje ct the possibility th a t o u r ju d g m en ts have been guided by some foolish procedure on the g rounds th a t it is implausible th at we would use such a p rocedure. O n e m ay go so far as to speculate th at a given cognitive procedure is likely to be m isidentified or unrecognized precisely to the degree th at it is in ap p ro p riate or foolish. A ctually, m atters m ay be even m ore u n settling th an this. W ork by Bern and M cC onnell (1970) and by G oethals and R eckm an (1973) indicates th at peoples’ ju d g m en ts m ay change in the absence of any recognition th a t a change has occurred. P articu larly u n n erv in g is the latter investigators’ d em o n stratio n th at subjects’ opinions of such an im p o rtan t issue as the “ bussin g ” of school children could be shifted from pro to con (or con to pro), by an eloquent speaker, w ithout the subjects’ recognition that their opinions had changed at all. I f the shift in ju d g m e n t itself is h idden from view, then the chances of recognizing the inap p ro p riaten ess o f an inferential strategy u n d erly in g th a t shift seem slim indeed. O n the other h an d , even if it is agreed th at we often fail to recognize that an inference has occurred, and can only guess at inferential procedures w hen we do recognize th a t an inference has taken place, m atters are n o t quite hopeless. W henever we find th a t we have m ade a decision or ju d g m e n t that seems surprising (eith er su rp risin g to ourselves or to others who know us well), then a m ore form al and self-conscious inferential strategy can be pursued. T h e result frequently will prove to be the u n m ask in g of a fam iliar cu lp rit— a lazy use of the representativeness heuristic, inattentiveness to sam pling bias, or reliance on dubiously relevant schem as or scripts. A T verskian anecdote offers a concrete illustration. T versky had accepted an invitatio n to atten d a conference. S hortly after he had done so, a colleague happened to ask him why he had accepted the invitation w hen he had refused so m an y others. T v ersk y h eard him self giving plausible, that is, “ rep re se n ta tiv e ” reasons for a tten d in g a conference ( “ I ’m interested in the to p ic ,” “ T h ere will be some in terestin g people th e re ” ), b u t they sounded

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curiously flat to him . O nce alone, he began to review the seem ingly appropriate justifications that he had offered. T h e topic? H e was not really all that interested in it and never had been. T h e people? A few m oderately interesting people, but no one exceptional, certainly no one both exceptional and otherw ise inaccessible enough to ju stify the trip. T h e tim e or circum stances? Inconvenient really, a b ad tim e to be tro ttin g off to a d istan t conference; no possibility even of com bining the trip w ith o ther, m ore necessary, undertakings. H m m . T h ere had been th at glossy bro ch u re ab o u t the conference site. An elegant hotel, a sandy beach, girls in bikinis, crystal clear w ater (all of which he w ould be able, at best, m erely to w atch from the w indow of the conference room as the m eetings d roned on). H m m . 4‘D ear Professor Sm ith: I had hoped to be able to atten d your conference in M ajo rca this A pril. U n fo rtu n ately . . . In other w ords, we often are given clues, frequently in the form of questions asked by other people, to the fact th at we hold some opinion, or have chosen some course of action, th at does not seem reasonable in light of the evidence and argum ents th at we curren tly can m uster. Som etim es th ere will be a tipoff, like T v ersk y ’s sudden m em ory of the glossy b rochure; b u t even when we cannot im m ediately uncover the cu lprit, a m ore form al appraisal m ay result in the discovery of some violation of n o rm ative inferential p rin ciples or sensible decision strategy.

V iv id Data and Inferences A bout the Self

A n u n fo rtu n ate b u t im p o rtan t im plication of the speculations offered in chapter 3 is that the ju d g m en ts an d inferences th at are of greatest personal im portance to the individual m ay be the ones that can least be touched by the norm ative considerations discussed in this book. T h e m ore vivid the d ata th at people confront, an d the m ore affect-laden or personally relevant the issues w ith w hich they deal, the less likely it m ay be that h ig h er-o rd er inferential routes— of the sort we are trying to im prove— will be used in the evaluation of evidence. T his is true to such an extent that people m ay have different standards of rationality, indeed even different stan d ard s of sanity, for inferences that touch deeply on the self than for those th at p ertain to o th er m atters. C onsider two exam ples. O ne of the authors recently read an essay w ritten by a y o u n g professional w om an discussing the problem s of balancing a new career and a new baby. A long the way, the w om an m entioned incidentally th at for a long tim e after the b irth of her bab y she had felt like a bad m o th er because she had had an inverted nipple and had been unable to b reast feed successfully. T h e “ reasonin g ” u nderlying such feelings is of course m anifestly flaw ed, b u t it does not lead one to conclude that the w om an in question was irratio n al. But consider

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how one w ould ju d g e a w om an who said, “ I feel th at Elaine is a b ad m o th e r” and then explained h er feeling by saying, “ W ell, she has an inverted nipple and c a n ’t breast feed h er b a b y .” Such an observation w ould pro m p t a strong suspicion that the speaker was out of her m ind. O r consider the plight of a person who has persuaded a visiting relative to take a la ter flight hom e th an originally planned so th at they could enjoy a relaxed d in n e r b eforehand. T h e relative agrees, takes the later flight, an d as a consequence dies in a ho rrib le crash. Inevitably, the grieving survivor w ould express guilt an d anguished self-castigation over “ cau sin g ” the death. T his w ould not be su rp risin g an d w ould not raise doubts about his inferential competence. N ow suppose, on the o ther h an d , th at an uninvolved observer, perhaps a neigh b o r of the survivor, w ere sim ilarly to castigate and blam e the survivor for his role in the tragedy. W e w ould label him a fool or a m adm an. T hese exam ples m ake it clear that inferences about m atters th at touch deeply u p o n the self have a u n iq u e status. T h ey seem to call u p o n cognitive structures that are less norm ative an d m ore prim itive than those th at figure in less personal inferences. M oreover, such structures cannot readily be superseded by m ore logical ones. W hen o ther people point out to the individual th at his inferences or feelings are distorted an d erroneous, he m ay accept this intellectually b u t scarcely be affected by it em otionally. T h a t is, he m ay recognize his error, and realize that he would not have m ade a sim ilar ju d g m ent ab o u t anyone else, b u t still rem ain trap p ed by his feelings an d by the prim itive inferential processes un d erly in g them . T hese observations are hard ly original insights into h u m an n atu re. If m atters were otherw ise, psychotherapists could be replaced by logicians. T he relevance of the observations to the question of the perfectibility of inference processes should be clear, how ever. It is the m ost personally im portant inferences that are the least likely to be affected by the pallid, norm ative principles discussed in this book. T his does not m ean that no im provem ent at all can be expected for this critical class of inferences. T o u n d erstan d intellectually that one has m ade an erroneous inference surely can convey some advantages. T h e half-life, as it w ere, of the m ore prim itive inferences m ay be reduced, so th a t w hen the vividness of the initial evidence has paled, the superior inferences m ay gain precedence at an earlier point th an w ould otherwise have been the case. Even while still in the grip of the m ore prim itive inferences, the individual m ay be able to anticipate relief and forestall selfdestructive actions. T o go beyond such small com forts, how ever, we w ould have to deny m uch of w hat we said about the vividness criterion in ch ap ter 3. It is not only the m ost personally relevant inform ation that has a profound, often too p rofound, im pact on o u r inferences. In fo rm atio n al concreteness, firsthandedness, even the skill of the tran sm itter of the in fo rm atio n , all th reaten to u n d erm in e the intuitive scientist’s analyses. O nce again, there are lim its to the value of u n d erstan d in g the im portance of sam ple size or of

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u n d erstan d in g the logical irrelevance of some of the factors th at co n trib u te to the vividness of a given piece of evidence. W e can n o t easily ^^will ourselves to attend to or rem em b er pallid inputs to the sam e degree as we do vivid ones. T h e form al scientist has evolved strategies th a t g u aran tee the n o tin g and recording of all data deem ed relevant on a priori grounds, strategies th at strip such data of their extraevidential features. C an the layperson, or the scientist w hen he is functioning like a layperson, sim ilarly free him self of the ty ran n y of his senses? O ften the answ er is yes! People som etim es can take preventive m easures. T o re tu rn to one of the a u th o rs’ favorite exam ples, consider again the ritual in which applicants for academ ic jo b s m eet th eir prospective colleagues and then culm inate their visit w ith a " jo b ta lk .” U n d e r some circum stances, the " e x tr a ” inform ation (inform ation beyond th at conveyed in résum és, letters of recom m endation, published an d u n p u b lish ed papers, an d so on) of‫־‬ fered by the ap p lican t’s visit m ight m ore profitably be avoided than purchased. T h e lim itations of the interview technique as a predictive tool have been dem onstrated repeatedly. It has proved largely useless for p red ictin g success in u n d erg rad u ate or professional school, success in the Peace C orps, and perform ance in various jo b s, including scientific occupations. T h e re is no com pelling reason to presum e that the academ ic jo b interview is any m ore valid as a predictor than are interview s for o ther jo b s or roles. H ow ever, if the argum ents of chapters 2 and 3 are given credence, there is little likelihood that the can d id ate’s prospective colleagues will be able to resist giving the vivid interview " d a t a ” far m ore w eight th an it m erits. C o n fro n ted w ith a living, b reath in g , candidate w ho poorly m atches th eir "h o t-sh o t psychologist” p ersona— one who seems nervous, confused, too eager to please, too w rapped up in dissertation details and insufficiently inclined to explore the fascinating intellectual pathw ays they suggest— they m ay find it difficult to hire that candidate even if the o ther evidence offers testim ony o f excellence that they recognize in the abstract to have far m ore diagnostic value than the jo b talk or interview data. T h ey m ay even sharply revise th eir estim ates of their previously esteem ed colleagues w ho tried to d u m p this m anifest incom petent on them! It seems to us that search com m ittees som etim es w ould be best advised to forgo the interview process altogether. T his w ould be the case, for exam ple, w here one candidate stands head an d shoulders above the others on the basis o f the " fo ld e r.” T o interview in such a case, an d to risk losing the candidate because the hapless person fails to m atch the com m ittee m e m b ers’ personae, is to place m ore weight on the validity of interview procedures th an eith er m easurem ent theory or the ex tan t evidence could ju stify . T h e re is an o th er, less drastic rem edy. O n e can com m it oneself, before a c a n d id a te ’s visit, to a fixed w eighting schem e in w hich the interview is assigned only a lim ited n u m b er of " p o in ts ” out of the total to be aw arded. In such a case, the rem aining points should be aw arded before the visit, so th at the reco m m en d a­

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tions, papers, academ ic aw ards, and so on, cannot be “ reev alu ated ” in the light of o n e ’s new “ insights” about the candidate. In m ost everyday ju d g m en ts, the best advice and the best norm ative strategy is sim pler. If one knows that one cannot avoid giving a particular d atu m far m ore weight than is justified by its probative value, then by all m eans one should avoid that d atu m and rely only on the evidence that, in dispassionate m om ents, one w ould rate as most useful for the inferential task at hand. T h e person considering w hich college to atten d , or considering w hich car to bu y , w ould do well to throw aw ay glossy brochures and avoid personal visits to cam puses or show room s that are likely to provide only the highly biased, but vivid, presentations of those who are simply trying to sell their product. S ocial versus I ndividual E pistemic G ains . O n e im plication of the preceding discussion is that the potential for collective inferential im provem ent m ay far ou tstrip the potential for individual im provem ent. W e are likely to be b etter able to see the m otes in o u r b ro th e rs’ eyes than to see the beam s in o u r own. T w o people on a search or adm issions com m ittee together are perhaps m ore likely to catch each o ther in the act of persona m atching than to catch them selves. In d eterm in in g the accuracy of governm ent gas mileage estim ates, C ongressm an Jo n e s is perhaps m ore likely to question the relevance of the gas m ileage of C ongressm an S m ith ’s n eig h b o r’s Blatzm obile than is C ongressm an Sm ith. G reate r social th an individual gains also can be anticipated on the basis of the simple m athem atical arg u m en t discussed in chapter 11. T h e larger the n u m b er of people who take part in an inferential procedure, the greater the likelihood that at least one person will have a norm atively superior strategy. A ssum ing that the possessor of a superior strategy should be able to gain at least some supporters (particularly if the participants have been train ed to appreciate norm ative considerations) this should g u aran tee that groups can be led to use m ore norm ative strategies even w hen individuals cannot. Indeed, com m ittees an d the institutions that they serve can put any increase in inferential sophistication to use by form alizing their decisionm aking procedures according to the norm ative consideratons they have come to ap preciate. All of the institutional decision-m aking dom ains we have discussed, including stu d en t an d em ployee selection, parole decisions, sales predictions, and public officials’ policy decisions, could so benefit. C ollective, in stitutional, and recu rren t ju d g m en ts are the ones which seem m ost capable of im provem ent. T h e “ d eb iasin g ” procedures discussed by K ah n em an and T versky (in press) and by Slovic (1976) are particularly ap p ro p riate for such ju d g m en ts, and the b arriers against change which we have discussed seem m uch w eaker for such ju d g m en ts. T he A ll-T oo-F undamental A ttribution E rror. For one type of erro r that people com m it, o u r own personal experience m akes us doubt that m uch im provem ent is to be expected. T h e reader will not be surprised, we trust, to

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hear the authors confess that in m ost of their everyday inferences about peo‫־‬ pie they cannot escape the i ‘fundam ental attrib u tio n e r r o r .” J u s t as we were before we becam e professional psychologists and before we read Lew in, H eider or M ischel and began to spread th eir gospel, we are inveterate trait theorists or “ dispositionalists” in most of our social dealings. W e still think of the individuals in our lives as being chronically and tran ssitu atio n ally nice or not nice, honest or dishonest, dependent or in dependent. T his is not to say that o u r quasi-public verbal behavior has not changed. W e do not enjoy having our colleagues and students say, in effect, “ N ah , n ah , fu n d am en tal attribution e rro r.” So we have driven the erro r u n d erg ro u n d , so to speak, where it undoubtedly continues to guide our ju d g m en ts to an extent that we believe, intellectually, to be insupportable. O n the other h an d , each of us can think of isolated instances, depressingly infrequent to be sure, in which o u r ju d g m en ts and behavior seem to have been influenced by o u r intellectual position on these issues. T h ere have been occasions when we were able to tem per otherw ise u n doubtedly overconfident predictions, and occasions when we have taken actions concerning students and em ployees that were guided by the recognition that undesirable b ehavior m ight be situationally rath er than dispositionally produced. A gain, we find that these intellectually preferable ju d g m en ts seem to occur in inverse proportion to the vividness and self-relevance of the behaviors (and of the people) we are ju dging. But it does seem to us that there has been at least some gain in our personal lives and still m ore in the relatively dispassionate arenas of o u r professional lives.

Broadening of Inferential C onfidence L im its

Epistem ologists from Bacon to Russell are agreed on a fundam ental and pervasive h u m an failing th at we alluded to at several points in this book, although we have not given it a ch ap ter or section of its own. T h is failing is the tendency tow ard overconfidence in o n e ’s ju d g m en ts, tow ard g reater certainty about o n e ’s assessm ents, theories, and conclusions than closely reasoned analysis could possibly justify. T h e em pirical evidence (see reviews by E inhorn and H o g arth , 1978; Fischhoff, Slovic & L ich en ten stein , 1977; Slovic, 1976) gives strong support to this generalization. W e have tried at various points (see chapters 6 and 8) to provide evidence for some o f the m echanism s that m ight produce m isplaced confidence— from the failure to recognize how m uch of o n e ’s u n d erstan d in g of the w orld is theory-based rather than data-based, to the failure to u n d erstan d the logic o f regression. M any philosophers seem to throw up their hands at the cocksure stance of the layperson and place their hopes only in the form al analyses of the philosopher or scientist. P erhaps this pessim ism is justified. But the auth o rs

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nurse the hope th at this book, and the general orien tatio n it presents, m ay of‫״‬ fer m ore than ju s t a n o th er edict from ivory-tow er types who enjoy the luxuries of caution an d conservatism . If people have a clearer notion about the kinds of ju d g m en ts and inferences that are likely to show erro r, and a clearer idea ab o u t the kinds of m echanism s that p ro m p t such erro r, perhaps their illfounded certain ty m ight be shaken. W e will review some of those errorp ro d u cin g m echanism s w ith a view tow ard show ing th eir relevance to the problem o f overcpnfidence. K nowledge structures and the variability of the entity . O ne of the oldest and m ost p ersistent criticism s of h u m an inference is the accusation that once people have applied a p articu lar label to a given object (and thereby applied a specific know ledge stru ctu re to it), th eir subsequent presum ptions ab o u t the object are ap t to owe too m uch to th at label and too little to $ny actual observations ab o u t the u n iq u e object. T h e G eneral Sem antics m ovem ent that enjoyed som ething o f an intellectual vogue in the 1950s and 1960s provided perhaps the latest voice for such m isgivings, w ith its insistent w arnings ab out the dangers of A ristotelian thinking, and its rem inders that “ m other #1 is not m o th er # 2 ” , th at ‘'m o th e r #1 at tim e 1 is not m o th er #1 at tim e 2 ” , and so forth. T h e present view point, we feel, adds som ething to such w arnings. It suggests the kinds of object categories th at we are particularly likely to be overconfident about. F or exam ple, it leads us to expect m ore errors and m ore severely m isplaced confidence in ju d g m en ts w hen the category in question lies in the social ra th e r th an the physical dom ain. T h e reason is obvious: Bigot #1 is far less likely to resem ble bigot #2 or the “ prototypic b ig o t’’ than oak tree #1 is likely to resem ble oak tree #2, o r the “ prototypic oak tr e e ,” and so forth. T h e sem anticists’ point readily can be m ade in m ore statistical or probabilistic term s: T h e variance in the characteristics of objects to w hich we have applied the same know ledge structures is usually greater th an we are likely to assum e while, conversely, the variance in objects to w hich we have applied different know ledge structures (especially if those objects happen to be people) is likely to be less th an we assum e. T heories and their justification . A n im p o rtan t step in reducing peop ie’s overconfidence w ould be taken by leading them to recognize th at th eir in terp retatio n s of events, ra th e r than being simple read-outs of data, are inferences that m ake heavy use of theory. O nce one recognizes that the sam e d a ta w ould look quite different, and could easily support different beliefs, if those d a ta w ere viewed from the vantage point of alternative theories, the groundw ork for a h u m b ler epistem ic stance has been laid. Such a recognition invites people to consider the logical o r em pirical status o f th eir p rio r theories and to adjust th eir confidence accordingly. W hen the theory is w ell-founded, its heavy use in the in terp reta tio n of am biguous events is correspondingly justified. B ut w hen the origin of the theory is dubious, its role in governing the in terp re ta tio n of d ata m ust be severely circum scribed.

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T his book has offered m any clues which m ight help people to identify theories that are suspect and are therefore unlikely to m erit heavy use in the in terp retatio n of data. F or exam ple, inform al theories of covariation norm ally should be considered suspect, as should ad hoc causal theories, especially those that seem to involve heavy reliance on the representativeness heuristic. E xtreme judgments and predictions . A b etter u n d erstan d in g of the n atu re of regression should p ro m p t caution ab o u t extrem e ju d g m e n ts an d predictions, that is, about precisely those ju d g m en ts an d predictions th at are m ost likely to be w rong and to result in d isadvantageous behavior. A n appreciation of regression should serve to m ake people stop an d reconsider w henever they find th a t they have arrived at an extrem e assessm ent: Is the theory underlyin g m y assessm ent sufficiently w ell-grounded? Is m y d ata sam pie sufficiently large and free of bias to justify m y extrem e d ep artu re from the central tendency of the population of objects or events ab o u t w hich I have m ade my assessm ent?

T H E R O LE A N D R E S P O N S IB IL IT IE S O F T H E S O C IA L S C I E N T I S T

It is not only the layperson who is frequently overconfident. It is appropriate for us to conclude this book by po in tin g to the dam age th at can be done w hen it is social scientists who are inap p ro p riately co n fid en t— particularly w hen they are overconfident in th eir efforts to guide effective policy m aking. In urging the teaching and freq u en t use of m ore norm atively ap p ro p ria te inferential strategies, we also are u rg in g an im p o rtan t role for the social scientist. It has been social scientists (an d philosophers) who have sought to identify inferential shortcom ings an d to develop m ore norm atively ap p ro p riate m ethods for collecting an d analyzing d ata, for testing theories, an d for integrating inform ation in the service of decision m aking. It is social scientists, m oreover, who serve as executors of the rich legacy of theory an d d ata accum ulated thro u g h the exercise of form al inferential strategies. O n e of o u r goals in w riting this book has been to provide a rationale for giving a larg er role to the form ally train ed scientist— in a rb itra tin g disputes over existing facts, in designing strategies for discovering new facts, an d in ev alu atin g the conflicting theories generated by the exercise of ‘in tu itiv e” science. T h e lofty position we are advocating for the social scientist necessarily carries w ith it some im p o rtan t responsibilities an d restrictions. W e are all too aw are of the destructive influence th at social scientists can have, an d have had, in justifying and even in itiatin g ill-advised and pernicious social policies. (K a m in ’s 1975 d o cu m en tatio n of the p art th at psychologists played in furnishing a “ scientific” rationale for the exclusionary im m ig ratio n policies in i­

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tiated in the U n ited States d u rin g the 1920s is one particularly shocking exam ple.) R eg rettab ly , it is inevitable that social scientists som etim es will be w rong in characterizin g p articu lar social problem s an d in predicting the im pact of p articu la r social rem edies. But the dam age, to o u r profession as well as to the society it serves and seeks to u n d erstan d , can be curtailed considerably. P erhaps m ost im perative is the need to show greater candor and hum ility. W e m ust learn to distinguish clearly, in o u r public statem ents as in o u r professional w riting, w hat is know n from w hat it is reasonable to presum e, w hat it is reasonable to p resum e from w hat it is possible to m ake an educated guess at, and w hat it is possible to m ake an educated guess at from w hat it is possible only to guess at. In other w ords, we m ust learn to be m ore forthright in spedfying w hen we are speaking as form al scientists, “ ex c a th e d ra ,” as it were, w illing an d able to defend o u r contentions against the exacting and conservative standard s that o u r science dem ands, an d w hen we are speaking essentially as intelligent laypeople or “ in tu itiv e” scientists. W e also m ust be m ore willing to concede that it is as m ethodologists and not as theorists th at we are m ost able to contribute. Seldom can we look to the findings and theories of our field to discover a firm basis for policy decisions. W h at we can do is help to find b etter ways of designing an d evaluating social program s. W e can defend the long term advantages of w ell-controlled exp erim ents over “ ch ea p er” and m ore politically expedient designs. W e can help to justify and design the best possible m ethods for data collection. M ost im p o rtan t, we can cham pion the cause of norm ative inferential strategies, and w arn against the dangers of purely intuitive ones, when the issues addressed are both em pirical and of pressing social concern.

SUM M ARY

T h e inferential goals of the layperson are best com pared not to those of the p u re scientist b u t to those of the applied scientist or practitio n er. T h e rules of p u re scientific in q u iry thus provide only a rough and approxim ate guide to lay inferential strategy, an d it will som etim es be pro p er to set them aside in favor of procedures th at facilitate action or that b etter serve extraepistem ic goals. T h e decision to substitute a relatively form al inferential strategy for a relatively inform al one, or vice versa, is dictated by cost-benefit considerations. D ecisions of little consequence generally will, an d should, be guided by intuitive strategies. At the oth er extrem e, recu rren t decisions w ith im p o rtan t consequences generally should be m ade w ith the aid of the best norm ative strategies available, even if these are relatively costly. P ro g ram s of secondary an d higher education should be revised to p ro ­

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vide people w ith a b etter g ro u n d in g in form al inferential rules. Statistics and probability theory should be tau g h t at least as early as secondary school, and curricula should feature discussion of the contrast betw een form al an d informal intuitive strategies. P roviding concrete, anecdotal exam ples of intuitive errors and teaching ju d g m en tal m axim s also should be helpful. T h o u g h the m ood of the book is optim istic ab o u t prospects for the improvem ent of h u m an inference, it m ust be recognized that there are serious barriers to change. People can n o t exam ine directly their inferential procedures and discover their flaws; the very m ost im p o rtan t personal ju d g m e n ts are apt to prove particularly im pervious to logical insights; an d people are apt to be so confident about most of their ju d g m en ts th at they are disinclined to exam ine them for the possibility of error. Social scientists, especially in the role of social advocates, are often open to the sam e charge of m isplaced certainty as the layperson. If social scientists are to be w orthy of the role that we advocate, they m ust specify w hen they are speaking as form al scientists and w hen they are speaking only as intuitive scientists.

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The nature of a controversy.

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