Performance of children in a discrimination problem as a function of symbolic guidance, delay of reward, and mental ability

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p i|pam & ra of children in a discrimination probiem AS A FUNCTION OF SYMBOLIC GUIDANCE, DELAY OF reward, and mental ability

Alfred Jacobs

A d issertatio n submitted in p a rtia l fulfillm ent of the requirements for the degree of Doctor of Philosophy in the Department of Psychology in the Graduate College of the State University of Iowa August 1950

ProQuest Number: 10598592

All rights reserv ed INFORMATION TO ALL USERS The quality o f this rep ro d u ctio n is d e p e n d e n t u p o n th e quality o f th e c o p y su b m itted. In th e unlikely e v e n t th a t th e au th o r did n o t se n d a c o m p le te m anuscript a n d th e re a re missing p a g e s , th e s e will b e n o te d . Also, if m aterial h a d to b e re m o v e d , a n o te will in d icate th e deletio n .

uest. P roQ uest 10598592 Published by ProQ uest LLC (2017). Copyright o f th e Dissertation is held by th e Author. All rights reserved. This work is p ro te c te d a g ain st unauthorized cop y in g u n d er Title 17, United S tates C o d e Microform Edition © ProQ uest LLC. ProQ uest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 48106 - 1346

AGKNGflMMTS

The author wish©a to express h is appreciation to Br« X* E. Farber and Dr* Arthur L* Benton fo r th e ir guidance in the course of th is in v estig a­ tion*

Thanks are also due to the s ta f f s and

resid en ts of Woodward State H ospital and School a t Woodward, Iowa, the Annie Httenm yer Hoiae a t Davenport, Iowa, St* Vincent’s Home a t Davenport, Iowa, the Lutheran Homes in Muscatine, Iowa, and the Lutheran C h ild re n s Home in Waverly, Iowa, fo r th e ir cooperation*

T h e U n iversity of Iow a LIB HA HIES

ii

wm of Gcmms Chapter I*

In tro d u c tio n .................................................................... The Bole of V erbalisation ............. V erbalisation and Belayo f %ward . «........... V erbalisation and Mental Development.............

II* III.

......................

10

Kaqperimental Procedure

..........................

13

......... ........... .................

R e s u lts ............................ Learning Analysis Analysis %mbolic

V*

Curves ................. of E ffects of Main V a ria b le s .................. ......... of In teractio n s Training .............

Discussion

..............

Summary.............. References Appendix A Appendix B

IS 18 23 31

Belay of Sew ard.............................. Symbolic Guidance ................. Groups of Subjects ................... In teractio n s ............................ VI.

1 3 6

Statement of the Problem

Subjects Apparatus Procedure IV.

1

51 38 46 49 55 55 55 @0 61 64

.......................... ............. .............................................

ill

71 73 77

TABLE OF COMMTS (continued)

Chapter

Page Appendix C ........... ........................ Appendix D

. ............. *........

85

Appendix S . . . . . . . . .......... . . . ..................... . . . . . . . . . . .

87

Appendix F Appendix 0

..................• ...........

8$

.......................................... ..................... . ............

Appendix K .............. . . . .......... Appendix I

........................................

iv

91 04 96 90

tabiu of Fimms Figure 1*

Page Schematic presentation of ih© design of th© experiment . . ........ ............ . . . ............................ . . . . .

12

2.

Stimuli used in the ex perim ent......................................

19

$«

Subject1a view of the a p p a ra tu s............... . . . . .............

21

4*

Experimenter's side of the apparatus

ZZ

5*

Schematised drawing of fro n t and back of the a p p a ra tu s . . ......................... * . . ...................... * 23

6.

The mean number of co rrect responses fo r blocks of fiv e t r i a l s on each of the three tasks fo r the four experimental subgroups from the sanple of older normals . . . . .................... .........

32

The mean number of co rrect responses fo r blocks o f fiv e t r i a l s on each o f th e three tasks fo r the four experimental subgroups from the i sample of younger normals .........

34

The mean number of co rrect responses fo r blocks of fiv e t r i a l s on each of the th ree tasks for the four experimental subgroups from the sample of mental d e f e c tiv e s ...............«•

36

The mean number of correct responses on each of the th ree task s fo r each of the three groups of subjects ................................

50

7.

8.

9.

v

. . . . . . ...........

TABES OF TABXBS Table I*

IX*

XIX*

XV* V*

VI*

VII,

VIII* IX*

gage, Means, Standard Deviations, and Medians of th© Total Number o f Correct Responses on A ll Thro© Tasks fo r Each of th e Twelve Eaperiraental Subgroups ......................

40

Means, Standard Deviations, and Medians of the Humber of Correct Responses on Task 1 Only fo r Subjects In Each of the Twelve Experimental Subgroups....................... . . . . . . . . . . .

42

Differences between the Mean Humber of Cor­ r e c t Rehouses on AH Sbree Tasks fo r th© Symbolic Guidance Conditions and fo r th© Delay of Reward Conditions fo r the Three Groups of S u b je c ts .............. . .............

4?

lean Humber of Correct Responses on Bach of Three Tasks by &ach of Three Groups ..........

SI

Means and Standard Deviation® of StanfordBinet Mental Ages (in Months) of Subjects in Each of the Four Experimental Subgroups in Each of the Three Groups of Subject® ............

74

Means and Standard Deviations of Stanford-* Binet In tellig en ce Quotient® of Subject® in Each of the Four Experimental Subgroups in Each of the Three Group® of Subjects ............

75

Means and Standard Deviation® of Chronological Ages (in Months) of Subjects in Each o f the Four Experimental Subgroups in Each of th© Three Groups of Subjects .................... .

7$

Orders of Stimulus Presentation fo r Symbolic Guidance Training and fo r Tasks 2 and 3 .........

84

D istribution of Response Button Combinations fo r Subjects in the Twelve Experimental Subgroups .................

@6

vi

TABLE or TABIES (continued) Table. X.

XX.

XXX.

XXXI.

XIV.

XV.

XVI.

gfffflt Mean and Indian Numbers of Correct Responses in Bach Block of Five T rials fo r the Three Tasks fo r Subjects in the Four Experimen­ t a l Subgroups from th© Sample of Older Orphans . ..............................*............ ***.................*.

88

Mean and Median lumbers of Correct Responses in Bach Block of Five Trial® fo r the Three Tasks fo r Subjects in th® Four Experiraent a l Subgroups from the Sample of lounger Orphans ..................... ............

89

Mean and Median lumbers of Correct Responses in Each Block of Five T rials fo r the Three Tasks fo r Subjects in the Four Experiment t a l Subgroups from the Sample of Mental Defectives ............................

* 90

Results of T riple C lassificatio n Analysis of Variance of the Total Number of Correct Responses on A ll Tasks Expressed as Normal ............... Deviates

92

Results of T riple C lassificatio n Analysis of Variance of the lumber of Correct Responses on Task 1 Alone Expressed as Log (SI - Num­ ber Correct) ...*«.*, ...........

93

Mean Number of Correct Responses on Task 2 and Taik 3 fo r Subjects Reaching th© C riterion on Previous Task® Only fo r Each of the Twelve Subgroups .........

9S

Means, Standard Deviation® and Median® of the Number of Correct Responses on Task Z fo r Subject® in Each of the Twelve Experimen­ t a l Subgroup® ......................................

97

v ii

m m

Of w sm *

(continued)

Table XVII*

Page Means, Standard Deviations and Medians of the dumber of Correct Responses on Task $ fo r Subjects in Bach of the Twelve Ex­ ............... *•*.**...... perim ental Subgroups

08

XVIII.

Number of Correct Bep o n se s on Bach of Three Tasks and Total Number of Correct Responses fo r Bach Subject from the Sasple of Older Orphans Under Immediate Reward . . . . . . . . . . . . . . . . 100

XIX*

Number of Correct Responses on Bach of Three Tasks and Total Number of Correct Responses fo r Bach Subject from th© Sample of Older Oarphan® Under Delayed Reward....................................101

XX*

Number of Correct Responses on Each of Three %sks and Total Number of Correct Responses fo r Each 'Subject H*om the Sample of lounger Orphans Under Belayed Reward . . . . . . . . . . . . . . . . . . 102

XXI*

XXXI*

XXIII*

Humber of Correct Responses on Each of Three Tasks and Total Number of Correct Responses fo r Each Subject from the Sample of lounger Orphans tinder Immediate Reward

IDS

Number of Correct Responses on Each of Three Tasks and T otal Number of Correct Responses for Each Subject from the Staple of Mental Defective® Under Immediate Reward *****...........

104

Number of Correct Response® on Each of Three Tasks and Total Number of Correct Responses fo r Each Subject from the Sample of Mental D efectives Under Immediate Reward *******.............105

w ill

i

Chapter X MROBCCtXCffif the Role o f V erbalisation On® o f the important ta sk s in the application of learning theory to human behavior i s to assess the significance of language in the production of behavior*

M iller and Bollard (11), in th e ir

analysis of so c ial learning, have stressed the importance o f language in supplying human beings w ith a re p e rto ire of cue-producing responses and have pointed out, in th is connection, th a t children receive ex­ tensive tra in in g in associating words to objects and responses to words*

The associations formed by th is tra in in g might be represent­

ed schem atically as follows s

That these mediating verbal processes can a ffe c t the be­ havior of children i s indicated by a number of experiments. Pyles (16) required children between the ages of two and seven years to find a toy hidden under erne of fiv e papier-mache "nonsense fig u re s."

She provided the children with "nonsense names"

fo r these fig u res, and required the children to vocalize the co rrect

2

name a f te r each of the f i r s t th ree co rrect responses and a t period­ ic in te rv a ls thereafter*

Other children who were not provided w ith

these "nonsense names’1 apparently were exposed to sim ilar rehears­ a ls a f te r co rrect responses, except th a t pointing and references to •’th a t shape" were e lic ite d instead of the "nonsense name*11 Her re s u lts suggest th a t the children supplied with name a were able to make a more rapid discrim ination than those not so supplied*

She

fu rth er found th a t when animal forms were used Instead of nonsense forms the discrim ination was most rapid, even though no names were supplied by the experimenter.

Although no te s ts of significance

were reported, the differences appeared highly re lia b le in terms of the standard erro rs of the means reported. Birge (2), in a carefu lly controlled study designed to demonstrate secondary stimulus generalisatio n , found th a t i f two d iffe re n t stimulus objects are assigned the same name by the ex­ perimenter, these objects are more lik e ly to be responded to in the same manner by the subject than i f the objects are given d iffe re n t names*

She also found th a t such tra n sfe r was more lik e ly to occur

in children in the th ird , fourth and f i f t h grades when the children were required to vocalise the mediating name than when they were not. Kuerrne (7), in an experiment on tran sp o sitio n in a v isu a l discrim ination problem w ith young children, reported th a t a l l c h il­ dren who spontaneously verbalized the relatio n sh ip of the differences

3

In the size o f the stim uli to success or fa ilu re in v ariab ly shewed transposition#

She fu rth e r reported th a t some o f her younger sub­

je c ts were able to v erb alise the problem solution when required to do so, but apparently were unable to use th is v erb alisatio n as a cue to d ire c t th e ir motor responses* The studies c ite d above suggest th a t th e re are two separ­ a te and independent processes involved in the effe c tiv e use of verbal behavior*

Th© f i r s t of these involves attaching words to

stim uli I the second involves attaching other responses to th© ver­ bal cues*

Pyles* study suggests th a t subjects who cannot or do not

in it ia t e verbal responses themselves may p ro fita b ly use cues which are supplied by others*

Kuenne *s study suggests th a t sons su b jects

say be able to attach words to objects, but unable to attac h appro­ p ria te responses to these words.

3*3^ M shssI Various authors have suggested th a t verbal and symbolic processes are the means by which human subjects counteract the e f­ fe c ts of delays of reward.

M iller and Bollard (11) and Lorge and

Thorndike (§) have hypothesised th a t i t i s the a b ility of humans to re in s ta te in symbolic form the stlmulus-response sequence a t th® time of reinforcement which n e u tra lise s the expected e ffe c t of delayed rewards.

4

Elsewhere M iller and Bollard have suggested th a t symbolic reward® are used by humans to provide immediate reinforcement in s itu a tio n s where innate rewards are deferred.

In a paragraph which

re fe rs both to the process by which the stimulus-response sequence i s moved closer to th© reward as w ell as to th a t by which the re ­ ward i s moved clo ser to the stimulus-respons© sequence* they write* With human subjects who have had the proper so c ial tra in in g , symbolic stim uli th a t have acquired a rewarding value are often used to bridge th® gap between the occurrence of an a c t and the occurrence of an innate reward. Money, or even th© thought of making money, can be immediately asso ciat­ ed w ith the performance of a taskj a f te r an in te rv a l the money can be associated with some primary reward such as e a t­ ing. In th is way, the decrement which would b® expected mi the b asis of the gradient of reward i s markedly lessened. Sim ilarly a parent punishing a child i s lik e ly to attempt to elim inate th® e ffe c ts of the time gap between ste a lin g and punishment by a verbal reh earsal of the circumstances of th© crime. As would b© expected, younger children who have had le ss tra in in g in responding to symbolic stim uli are le ss affected by such a procedure, and hence more influenced by immediacy of reward. . . . But even in such cases in which w ell established h ab its of responding to symbolic stim uli help bridge the gap between the response to a cue and the re ­ ward of th a t response, th© gradient of reward i s not complete­ ly masked} more immediate rewards are reg u larly more effec­ tiv e than more remote ones. (1 1 , page 46) The experiments on the ro le of language in c h ild re n 's learning which have been cite d have involved immediate rein fo rce­ ment*

Although the use of verbal cues may f a c i lita te learning in

situ a tio n s in which the reward i s immediate, as in P yles' study, i t may b© assumed th a t, so long as the stim u li are a t a l l

5

discrim inable, learning would occur even in th© absence of verbal behavior*

TSher© reward i s delayed, however, verbal behavior may

play an even more important role*

By making d iffe re n t verbal re ­

sponses to d iffe re n t stim u li, subjects provide themselves with d if fe re n tia l p attern s of respon se-produced stim ulation which may p e r s is t over an extent of time*

The presence of these d if fe re n tia l

trac es (verbal, symbolic, or proprioceptive) of responses appears to be e s s e n tia l fo r learning in situ a tio n s where reward is delayed, i f other sources of secondary reinforcement are controlled*

The

manner in which trac es may operate to counteract the e ffe c ts of delays in reward has been explained by Spence (19) and Grice (4) in the following manner; A p a rtic u la r p a tte rn o f stim ulation re su ltin g from or accompanying the correct response may become a secondary rein fo rcin g agent i f i t p e r s is ts u n til the time of reward*

On subsequent occur­

rences of th© response, the stim uli re su ltin g from or accompanying the response, being sim ilar to the trac es p e rsis tin g u n til the time of reinforcement, could, through generalisatio n , provide immediate secondary reinforcement* Although animal studies have confirmed Hull*s p o stu late (S) w ith regard to the inverse rela tio n sh ip between temporal delay of reward and ra te of learning when secondary rein fo rcin g e ffe c ts have been controlled, studies of the e ffe c t of delay o f reward fo r

6

human subjects have not co n sisten tly reported th i s re la tio n sh ip . For example, Thorndike (20) has reported an experiment in which subjects were required to give a number In response to a word spoken by the experimenter-

&t 0, 2, or 4.5 seconds afterw ards the

experimenter said rig h t or wrong,

there was no difference in the

number of re p e titio n s of rewarded connections as a function of the in te rv a ls of delay, although Thorndike rep o rts th a t the spread of e ffe c t was diminished by longer delay. Lorge and Thorndike (9) have reported a b a ll to ssin g ex­ periment involving money rewards and penalties*

Delays of 0, 1, 2,

4, and 6 seconds elapsed between response and reward.

They concluded

th a t there was s t i l l some improvement in accuracy o f response with delays of up to s ix seconds, but th a t delays of four and s ix seconds seemed to lessen the improvement* Rock (17), in a lin e drawing experiment, informed blind­ folded subjects whether they had been rig h t or wrong on the previous t r i a l e ith e r before or a f te r the mental m u ltip licatio n s which separ­ ated each t r i a l from the next.

He reported s lig h tly superior learn ­

ing when the a fte r- e f fe c t immediately followed performance* V erbalisation and Mental Development Since i t has been shown th a t verbal processes a ffe c t learn ­ ing in children, and since i t has been suggested th a t these processes

7

are also a means by which the e ffe c ts of delays in reward are coun­ te ra c te d , i t might be expected th a t subjects who d iffe r in th e ir a b ility to use verbal processes would also d if fe r in the ra te s a t which they are able to learn ta sk s involving mediating verbal r e ­ sponses, p a rtic u la rly under conditions of delay in reward* The a b ility to use verbal cues i s undoubtedly a fa c to r d iffe re n tia tin g the performances of children of various ages#

In

normal children, the us© of language or other symbolic cues appears to be a function of chronological and, th erefo re, % ental a g e .H Not only are older children more adept than younger children a t de­ fin in g words | they excel in th® performance of task s referre d to a s reasoning and ab stractio n (12) which are assumed to involve the use of symbolic behavior.

Since most in te llig en ce t e s t s are heavily

weighted with items involving verbal s k il ls , "mental age” i s , to a considerable ex ten t, a measure of th is a b ility to use verbal and symbolic behavior.

However, since other a b i l i t i e s also contribute

to "mental age" scores, i t would be quite possible fo r subjects of the same "mental age" to d if fe r somewhat in th e ir a b ility to use verbal behavior* Comparisons of the performances of normal and m entally d efic ien t subjects of the earns "mental age" on standardised i n t e l l i ­ gence hnd achievement te s ts in d icate th a t the l a t t e r show le s s a b ility than normal subjects in the effectiv e use of language, as

8

measured by such items as completing sentences, language usage, su­ p erio r d e fin itio n s, and giving s im ila ritie s and differences ( l , 10, 1$, 21)*

The re s u lts of various in v estig atio n s in th is area have

not been alto g eth er consistent and, as some authors suggest, d iffe r­ ent items may be d if fe re n tia lly affected by age and experience. However, the re la tiv e in f e r io r ity of mental defectives on items pur­ portedly requiring ab stractio n , reasoning, and lin g u is tic manipula­ tio n appears to bo generally substantiated* Since older children are b e tte r able to use verbal process­ es than younger children, and since mentally d efic ien t children are reportedly le s s able to us© verbal processes than children of compar­ able mental age, i t might be expected th a t older children would be superior to younger and in te lle c tu a lly normal children to mentally defective in th© learning of tasks involving mediating verbal behav­ io r , p a rtic u la rly under delay in reward* I t may be noted th a t the facto r of in s titu tio n a lis a tio n i s an important variable th a t has not been controlled in the m ajority of studies comparing normals and mental defectives*

Aside from mo­

tiv a tio n a l differences which possibly e x is t between in s titu tio n a liz e d and non-in s t n a tio n a liz e d subjects, i t has been shown th a t in s t itu ­ tio n alized children have vocabularies in fe rio r to those of normal subjects w ith whom they have been matched fo r chronological age, mental age, or in te llig en ce quotient (22)*

In s titu tio n a liz a tio n i s

9

a v ariab le which i t i s therefore perhaps p a rtic u la rly ijaportant to control in attempts to evaluate difference® in performance o f nor­ mals and defectives on task s involving v erb ally mediated behavior.

10

Chapter I I SOtkWOSSt Of THE PROBLEM

The present experiment was designed to in v estig ate the performance of children in a discrim ination problem a a a function of symbolic guidance, delay o f reward, and mental a b i lity . Three groups of in s t itu tio n a liz e d children were used. groups consisted of orphans equated for Stanford-Bimet I.Q.

Two

One

group was composed of older orphans whose mean chronological ag© was ten years.

A second group, composed of younger orphans, had a mean

chronological age of six years and five months.

A comparison of

these two groups allowed an evaluation of changes in discrim ination performance under the experimental conditions as a function of the mental development facto rs which are measured by mental and chrono­ lo g ic al age in in te lle c tu a lly normal subjects.

A th ird group, con­

sis tin g of in s titu tio n a lis e d mentally defective children without obvious physical anomalies or obvious sensory d efects, was equated with the younger orphans fo r mental age.

A comparison of the mental

defectives and the younger orphans allowed an ©valuation of d if fe r ­ ences in discrim ination performance under the experimental conditions as a function of I.Q . differences in subjects of the same mental age* Two conditions of symbolic guidance were used.

Under Con­

d itio n I (no symbolic guidance) h a lf of each group was not given

11

names to designate th e stim uli to be discriminated*

The experiment­

e r gave members of the other h a lf of the group a name to designate each stimulus to be discrim inated (Condition I I , symbolic guidance) » and allowed these l a t t e r subjects to p ractice using these verbal responses to the stim uli before the introduction of the discrim ina­ tio n problem*

I t w ill be noted, th erefo re, th a t the f i r s t of these

groups had no assistance from the experimenter e ith e r in attaching verbal responses to th© experimental stim uli or In attach in g other responses to verbal cues*

The second group however was supplied

with a verbal response fo r each experimental stimulus, although I t was not given any aid in attaching other responses to th is cue* Half of the subjects in each subgroup received an immedi­ a te reward each time they associated a co rrect button-pressing response w ith one of th ree v isu a l stim uli to be discriminated*

This

w ill be referre d to as immediate reward* The other h a lf was reward­ ed 23 seconds a f te r th® occurrence of a co rrect response*

This

condition w ill be referre d to as delayed reward* The d esi^ i of the experiment was a f a c to ria l one involving three v ariab les, and m y be schematised as shown in Figure 1*

The

abbreviations used to designate subgroups in subsequent ta b le s w ill be found in the appropriate c e lls of the drawing*

12

to

Symbolic Guidance

SG-Q

SG-23

No Symbolic Guidance

NSG-0

NSG-23

ra

&

Immediate Reward

Figure 1.

so$'

Delayed Reward

Schematic presentation of the design of the experi­ ment. (Ten subjects were used in each c e ll.)

18

This design perm itted an analysis of the e ffe c ts of the following th ree v aria b les and th e ir in te ra c tio n s in a discrim ination problem? (l) Differences in

extent of

mental development*

(&) Differences in

extent of

symbolicguidance*

(s)

extent of

delay of reward*

Differences in

She following hypotheses were tested? HI*

On the assumption th a t r a te of learning i s in v ersely

re la te d to extent of delay of reward, i t m s predicted th a t subjects experiencing immediate reward would give a g reater number o f co rrect responses on the discrim ination problems than those experiencing delayed reward* Hg.

On the assumption th a t the amount of symbolic guid­

ance supplied i s p o sitiv e ly re la te d to learning a b ility In children, i t was predicted th a t subjects experiencing the pre-discrim ination verbal tra in in g would give a g reater number o f co rrect responses fo r the discrim ination problem® than those not experiencing such training* H3.

On the assunption th a t M*&*, X»Q*, and C.A. are r e la t­

ed to the capacity to use symbolic behavior and th a t th is capacity i s d ire c tly re la te d to learning a b ility in children, i t was predicted th a t the older normals would give a greater number of correct

14

responses fo r the discrim ination problem than the younger normals, and th e younger normals a g reater number than th© mental defectives* H4* I t was predicted, with regard to in te ra c tio n s, th a t the older normals would shew a b e tte r performance when reward was delayed re la tiv e to when reward was issaediate than the younger nor­ mals, and the younger normals would show a b e tte r performance than the mental defectives* H5.

I t was predicted th a t the older normal® should p r o f it

more from symbolic guidance than the younger normals and the younger normals more than the mental defectives* H6* I t was predicted th a t the eaqperience o f symbolic guidance should lead to g reater increase® in th e number of co rrect responses under conditions of delayed reward than under immediate reward* H7*

I t was predicted th a t older normals would p r o f it more

than younger normal® by symbolic guidance, under delay of reward, and younger normals more than mental defectives*

15

C hapter I I I EXPERIMENTAL PROCEDURE

Subjects Three groups of in s titu tio n a liz e d children were used*

a

group of 40 mental defectives; a group of 40 young orphans equated Tilth the mental defectives fo r mental age; and a group of 40 older orphans who were approximately go months younger than the mental defectives in chronological age.

A ll subjects with obvious physi­

c a l anomalies or sensory d efects were excluded from the study* Mental Defectives These subjects consisted of 2? males and 13 females who were resid in g a t the Woodward S tate H ospital and School a t Woodward, Iowa, a t the time o f the study.

These p a tie n ts were free from ob­

vious physical stigm ata such as those c h a ra c te ristic of mongolism, cretinism , or the various c ra n ia l anomalies.

No attempt was made to

d iffe re n tia te between so -called "endogenous1’ and "exogenous" d efect. The p a tie n ts selected had a mean chronological age of 11 y ears, 9 months, w ith a range of 9 years, 11 months to 14 years; a mean mental age of 6 y ears, 2 months, with a range of 4 y ears, 6 months to 8 y ears, 1 month; a mean I.Q. of 53, with a range of 41 to 70, and a mean duration of h o sp italizatio n o f 5 years, 3 months, w ith a range of 1 month to 9 years, 3 months.

Equal numbers of p a tie n ts w ithin th is

IB

group were assigned a t random to each of four experimental conditions. lounger Normals

These subjects consisted of 24 males and 16 females resid ­ ing a t one s ta te orphanage and th ree denominational orphanages in Iowa a t the time of the study.

Fourteen subjects were secured from

a s ta te orphanage, the Annie Wittonmyer Home in Davenport; th irte e n subjects from the Lutheran C hildren's Home in Waverly; fiv e were from the Lutheran Homes in Muscatine; and eig h t were from S t. Vin­ c e n t's Home in Davenport. The mean chronological age of the younger orphans was 6 years, 5 months, with a range o f 4 year$ 8 months to 7 years, 11 months; th© mean mental age was 6 years, w ith a range of 4 years, 1 month to 7 y ears, 8 months; the mean I.Q . was 94, with a range of 78 to 115; and the mean duration o f in s titu tio n a liz a tio n was 1 year, S months, w ith a range o f 1 month to 3 years, 6 months.

Ten sub­

je c ts were randomly assigned to each o f four experimental conditions w ithin th is group. Older Normals These subjects consisted of $3 males and 7 females re s id ­ ing a t the Annie Wittenmyer Home a t Davenport a t the time of the study.

The mean chronological age of the older orphans was 10 years,

w ith a range of 8 years, 2 months to 11 years, 6 months; the mean

17

mental age was 9 years, 1 month, with a range of 7 years, 3 months to 13 y ears, 1 month} the mean I.Q. was 91, w ith a range of 78 to 116} and the mean duration of in s titu tio n a lis a tio n was 3 y ears, with a range of 1 month to 11 years, 1 month*

Ten subjects were randomly

assigned to each of four experimental conditions w ithin t h i s group. Of the 120 subjects, 109 had been administered the Stanford-Binet by psychologists employed by the p riv ate in s titu tio n s or by the S tate of Iowa.

The remaining 11 were given abbreviated

Stanford-Binet b a tte rie s by the experimenter one day previous to the su b jects1 p a rtic ip a tio n in the experiment*

Ninety-seven of the

Stanford-Binets had been administered w ithin the year preceding the experiment*

Of the remaining 23, none had been administered over

four years previous to the experiment*

None of the Stanford-Binets

administered to th e younger orphans was older than two years.

Men­

t a l ages a t the time of the experiment were computed by m ultiplying the age of th e subject a t the time o f th e experiment by the I.Q* reported on the most recen t t e s t . The means and standard deviations of C.A., M.A., and I.Q . fo r each o f the three types of subjects, and fo r each of the four experimental subgroups w ithin each of these groups are presented in Appendix A.

I t may be observed th a t, as expected on the b asis of the

random assignment to subgroups, the four subgroup means fo r the same type of subject are highly sim ilar when compared fo r any on© of the

18

measures of mental development.

I t appears c le a r from inspection

th a t the v a r ia b ilitie s among these groups of four means are minor in comparison to the v a r ia b ilitie s -within the groups of subjects. I t should be noted* however* th a t the symbolic guidance - immediate reward subgroup tends to have the highest M.A* and the symbolic guidance - delayed reward subgroup to have th e lowest M.A. fo r a H types o f groups of subjects.

The groups under immediate reward

conditions appear to have s lig h tly higher I.Q. 's and M.A. *s than those under delayed reward conditions. Apparatus The experiment was performed in rooms provided a t the various In s titu tio n s .

Subjects were seated a t a table* with B

seated opposite behind a wall-board screen two fe e t high and three fe e t long. Two types of v isu a l stim uli were used*

A l Mx lJ H p ic tu re

of a man* and a sim ilarly sised p ic tu re of a woman were mounted to be exposed through an aperture in the screen as a demonstration dur­ ing the in stru c tio n s.

In addition* two se ts o f the v isu a l stim uli

presented in Figure Z were prepared fo r use in th e experiment#*

Qm

*The stim uli used in the present in v estig atio n are m odifications of stim uli devised by Miss Hita Serif, Psychologist a t the U niversity of Iowa Psychopathic H ospital.

19

Figure 2*

S tim u li Used in the Experiment

20

s e t m s mounted on 3nx5H cards to be used in a pre-experiiaental tra in in g se rie s , and an id e n tic a l se t was mounted to be exposed through th e aperture in the screen* A photograph o f the apparatus as seen from the subjects* view i s presented in fig u re 3, and as seen from th e experim enter*s view In Figure 4*

b e tte rs in th e follow ing te x t re fe r to le tte re d

u n its of the apparatus as shown on a schematic rep resen tatio n o f the apparatus In fig u re 5* Stim uli were exposed singly through a rectan gular opening (a) 5wx3w which was lo cated 8* from the top o f the screen and equi­ d ista n t from the sides*

Stimulus cards were fastened to a wooden

door (j) and were exposed by swinging the door upwards and latch in g i t manually. When a stim ulus was completely exposed* a m etal tab on the door activ ated a m icro-sw itch (h) which sta rte d a standard .e le c tric tim er ( t) used to measure the laten cy of the subjects* re ­ sponses to the stimulus*

E withdrew th e stim ulus by ro ta tin g th e

la tc h (g) 45 degrees by means of a strin g passed through a pu lley and allow ing the door to f a l l back by gravity* A response choice device consisted o f th re e push buttons (b) mounted 1*« ag art immediately beXcm th e e n s u r e aperture on the fro n t of th e screen*

From l e f t to rig h t the buttons were colored

red , yellow , and green*

Three p re -se le c to r toggle sw itches (r)

operated by E determined which one o f th e th ree b uttons would be

Figure

3.

S u b je c t’s view

of the ap p aratu s

21

Figure

u.

E xperim enter’s side

of the apparatu s

22

2a

n

F r o n t View

L

j-

=□ rj

pa

n

re**

H

x iy

‘ v v:

\9 F r

Fear Figure 5 .

Vie w

Schem atized drawing o f f r o n t and back of th e a p p a ra tu s. (Not drawn to s c a l e .) L e tte rs r e f e r to p a rts o f ap p aratu s l i s t e d below: a screen a p e rtu re b push b u tto n s c wrong sig n a l d rew ard box e sto rag e tube f marble r e tu r n s l o t g la tc h h m icro-sw itch i sig n a l l i g h t s exposure door 3

k 1 m n 0 P

q

r s t

reward chute wrong sig n a l b u tto n r e s e t sw itches marble re tu rn b e l l s ig n a l b e ll time delay device tran sfo rm er p r e - s e le c to r sw itches re la y s e l e c t r i c tim er

24

co rre c t on a given tr ia l* Each tim e a response occurred, th ree rela y s (s) operated to stop the e le c tric tim er and to illu m inate on© of th ree s ix v o lt bulbs ( i) which in d icated to £ which button had been pushed* v o lt house b e ll (e) rang i f a co rrect response occurred*

A s ix

th e tim e

in te rv a l between th e button pushing response and th e rin g in g of the beH was s e t a t e ith e r 0 or £8 seconds by means of an e le c tro n ic tim e delay device (p)*

The sound of th e b e ll was term inated manually

by means o f a re s e t sw itch Cut)* k second sw itch (m) was used to break the c irc u it in order to re s e t the e le c tric tim er and th e pre­ se le c to r switches* A fter th e term ination o f the b e ll follow ing a co rrect re ­ sponse, a reward, co n sistin g of a blue or brown marble was ro lle d through a brass tube (k) in to a reward box (d) a t th e base o f th e screen*

The fro n t of the reward box consisted o f a th in s tr ip of

tran sp aren t p la s tic E’M iigh and Sfl long, and the sid es were con­ stru cted of th in s tr ip s of wood of the same dimensions.

The box

had no top and i t was attached to the screen a t the p o in t where an aperture l | ,f in diam eter served a s an e x it fo r th e reward d eliv ery tube* The marbles acquired by making co rrect responses were stored in a cardboard tube (a) £-3/4 tt high and 1Mla diam eter, which had a -|w s tr ip cut out down th e length o f the tube and

25

replaced by cellophane.

This tube held fiv e marbles o f the siz e

used in the experiment# A fter subjects had acquired fiv e m arbles, they deposited th e marbles in a c irc u la r aperture (f) so th a t they ro lle d in to the in v erted reson ator of a house b e ll (n ).

A fter a l l fiv e marbles had

been deposited, E dropped a Hershey ^chocolate k is s 11 in to the reward box# When the subject pushed a wrong button, a six v o lt bulb (e) mounted |® below th e middle push button wag illum inated by I fo r one second by means o f a manually operated push button (1) e ith e r imme­ d ia te ly or Z$ seconds la te r as measured by a stqp watch. A ll c irc u its were operated by cu rrent supplied through a s ix v o lt transform er (q) except th e clock c irc u it which used 110 v o lt lin e cu rren t. Procedure Demonstration Subjects were informed by 38 th a t they were going to play a guessing game in which they could win some candy.

A dem onstration,

which was designed to fa m ilia rise su b jects w ith the procedure and the in stru c tio n s was then p resen ted .2 The p ic tu re of the man or th e woman was exposed in the screen, and E demonstrated th a t the b e ll

^Verbatim in stru c tio n s and order of procedure are presented in Appen­ dix B

26

would rin g i f th© •correct* button was pushed*

A marble was then

delivered which th© su b jects were perm itted to exchange fo r a piece o f candy*

The a lte rn a te dem onstration stim ulus was then ©aposed

t© shew th a t an "in c o rre c t0 response caused th e "wrong response sig ­ n al" to become illum inated in stead of producing rewards#

The sig­

n als and rewards were presented Immediately a f te r the button pushing responses were demonstrated fo r subjects to be used In the immedi­ ate reward conditions* and a f te r a delay of £3 seconds fo r su bjects to be used in th© delayed reward groups# Symbolic Guidance tra in in g The neat tra in in g period was designed to give two le v e ls of symbolic guidance.

In th® condition ch aracterised as no symbolic

guidance, th e stim u li which were to be used In the discrim ination were presented sin g ly on 3°3c5fl cards fo r fiv e seconds each* and the subjects were informed th a t these were the p ic tu re s to be used in the game# As each stim ulus was presented, su b jects w ere in stru c te d th a t only one button was co rrect fo r each p ic tu re , and th a t i f th e co rrect button was pressed when the stim ulus appeared, the b e ll would rin g and a marble would be delivered, whereas i f an in c o rrec t button was pressed, the lig h t would fla sh on and no marble would be delivered# In the condition characterized as symbolic guidance, dur­ ing th e fiv e seconds th a t each stim ulus was exposed on the 3f,x5n

27

card, su bjects were informed what i t represented, i . e . , a b ird , a dog, or a car*

She cards were then presented sin g ly in random

order to each subject under the symbolic guidance condition, and he was requ ired to r e c a ll the name® by which th e stim u li had been designated* & When a subject had named each stim ulus c o rre c tly on th ree consecutive p resen tatio n s, he was considered to have reached th e symbolic tra in in g criterio n * Experimental Procedure The experiment proper was in itia te d immediately a f te r the completion of th e symbolic training*

Th© procedure was designed to

give two conditions o f delay of reward w hile keeping the in te rv a l between p resen tatio n o f successive stim u li the same fo r both condi­ tio n s .

For a l l su b jects, m in te rv a l o f between 85 and 30 seconds

elapsed between p resen tatio n of successive stim uli* exposed fo r fiv e seconds*

A stim ulus was

I f no response was e lic ite d w ithin fiv e

seconds, th e stim ulus was withdrawn and an in c o rre c t response was recorded fo r the t r i a l .

Since, fo r a l l su b je cts, the next stim ulus

was always presented 85 seconds a f te r th e occurrence o f th e preced­ ing response, i t can be noted th a t the in te rv a l between successive Stim uli would be c lo se r to 30 seconds when the response latency was la rg e , and clo ser to 85 seconds when the response latency was small* ^Orders of p resen tatio n of stim u li are presented in Appendix C*

28

fo r the immediate reward group, when a c o rrect response occurred w ithin th e fiv e second stim ulus p resen tatio n p erio d , the h e ll rang iim oediately, and was term inated by E, who then d elivered a marble through the reward chute and removed the stim ulus card* When an in c o rrec t response occurred, E illum inated th e "wrong re ­ sponse sig n al" fo r one second and then removed the stim ulus card* Twenty-five seconds la te r E said "read y /1 and exposed the next stimulus* fo r the delayed reward group, when a co rrect response oc­ curred w ithin th e stim ulus p resen tatio n period, the b e ll was auto­ m atically sounded 25 seconds a f te r the occurrence of the response, and 1 delivered a marble*

I f an in c o rrec t response occurred, E

sta rte d a stop watch and, a f te r 25 seconds, turned on th e lig h t sig n a llin g wrong fo r one second*

The stim ulus card was always re ­

moved one second a f te r the occurrence of a response.

Two seconds

a f te r the s i © id fo r th e co rrect or in c o rrec t response, I said "ready" and presented th e next stimulus*

A fter th e su b ject had ac­

quired fiv e marbles he was reminded by E th a t he could exchange these fo r a piece of candy, and was perm itted to make the exchange before the p resen tatio n of th e next stimulus* The discrim ination problem was divided in to th ree parts* For the f i r s t ta sk , the stim ulus resem bling the b ird was exposed on each t r i a l u n til the su b ject reached a c rite rio n o f th ree consecutive

29

c o rrect responses o r u n til he had responded 30 tim es w ithout reach­ ing the

c rite rio n .

^

su b jects who made SO consecutive responses to

the same wrong button were informed before the S lat t r i a l th a t they could push any button they wished* A® soon as the c rite rio n fo r the f i r s t ta sk was reached, th e sub ject was required to learn which o f the th ree response buttons was co rrect fo r the stim ulus resem bling th e b ird and which one was co rrect fo r the stim ulus resem bling the dog*

These two stim u li were

presented a lte rn a te ly except m t r i a l s 3, 11, 16, and ZZ9 where the stim ulus appearing on th e previous t r i a l was repeated*

This proced­

ure was intended to in su re th a t any learn in g which occurred would be based on d ifferen ces in th e form of th e two stim u li, ra th e r than on the form ation of a simple a lte rn a tio n habit* The c rite rio n fo r the second ta sk was th ree consecutive co rrect responses to the stim ulus resem bling th e dog, and two con­ secutive c o rrect responses to th e stim ulus resem bling the b ird , w ith no in c o rrec t responses interven ing .

Subjects who fa ile d to

reach the c rite rio n on e ith e r Task 1 or Task 2 w ithin th e a llo tte d ^Prelim inary in v e stig a tio n s revealed th a t i t was extrem ely d if f ic u lt fo r ch ildren in the age ranges studied to learn to make a d iffe re n t button-pressing response to each of th ree stim u li when the order of p resen tatio n was derived from a l i s t of a l l th ree stim u li arranged in random order. The th ree task s used in th e p resent study were th erefo re devised in order to provide th ree discrim inations of in ­ creasing com plexity, th e f i r s t of which would be re la tiv e ly easy fo r the types of subjects studied*

30

SO t r i a l s war® no t perm itted to continue w ith any subsequent task* A fter su b jects had reached the c rite rio n fo r Task 2, they were requ ired to discrim inate between a l l th ree stim u li presented in random order except fo r the q u a lific a tio n th a t no stim ulus occurred tw ice in succession.

Subjects were perm itted 50 t r i a l s in

which to make th ree consecutive co rrect responses to each of these th ree stim u li. The push button which was assigned to a subject as the co rrect response fo r a p a rtic u la r stim ulus remained the co rrect re ­ sponse to th a t subject during a l l th ree ta sk s.

There were s ix pos­

s ib le combinations in which each button could be associated w ith a d iffe re n t stim ulus.

One combination was randomly assigned to each

subject*5 At the conclusion o f the experiment* subjects who had ex­ perienced th e symbolic guidance condition were shown th e stim u li sin g ly and asked to r e c a ll th e name th a t had been assigned.

Sub*

je c ts who had been given no symbolic guidance were shown th e stim u li and asked i f they had independently assigned any names to th e stim ­ u li during the experiment*

®The assignment of button combinations fo r the various samples and subgroups i s presented in Appendix D.

31

Chapter HT RESULTS Learning: Curves & ■£»>■■uj.ULJBt ssssssssstisi Figures 6 through 8 in d icate th e number of co rrect re ­ sponses over the th ree task s fo r the th ree groups of su b jects. Tables showing the mean and median number o f co rrect responses fo r each of th e p o in ts represented on these fig u res are presented in Appendix £• Older Normals (Jfean M.A* as 9 years* 1 month) Figure 6 p resen ts the mean number of co rrect responses in each block of fiv e tr i a l s on each of the th ree task s fo r the four experim ental subgroups drawn from the group o f older normals.

Bach

curve i s based on te n su b jects, and su bjects who fa ile d to reach the c r ite r ia fo r any ta sk were cred ited w ith scores of aero in the computation of means fo r any subsequent tasks*

Subjects reaching

the c r ite r ia before the p resen tatio n of 30 t r i a l s were cred ited w ith co rrect responses between th e t r i a l on which the c rite rio n was reached and th e 30th tr ia l* I t w ill be noted th a t the curves rep resentin g the mean num­ ber of responses fo r delayed reward subgroups exceed one of the curves fo r th e immediate reward subgroups a t only two p o in ts and are below both immediate reward curves a t 11 points*

The curve fo r the

32 UJ

o

o

z < Q Z>

LU

O

z: