21

THE ROTE AND CONCEPT LEARNING OF IMBECILES

BY BEATE H E R M E L I N AND N. O'CONNOR

Medical Research Council, Social Psychiatry Research Unit,

Maudsley Hospital, London

INTRODUCTION

Previous work has demonstrated the capacity of defectives, of feeblemindedas well as of imbecile grade, to learn simple tasks to an unexpectedly high levelof performance. The deficit of their thought processes however, which effectivemotivation only partly overcomes, has received little attention.

Burt's (1946) specification of learning deficiency among the mentally handi-capped, in which he shows some functions to be more affected than others, isone of very few attempts in the last fifty years to study the way in whichdefectives differ from normals in their thinking. The original conception ofBinet in which specific deficiencies were described, has been lost sight of inthe embracing concept of the intelligence quotient. Thus until recently whenan I.Q. had been determined, classification was considered complete. Some-times, as in the work of Duncan (1942) among others, a verbal/performancedifference is recorded and tests like the Wechsler Bellevue scale can be used togive such a measure. Useful as a concept of different kinds of I.Q. may be itstill does not raise the question of deficiencies of specific function in detail.

Recently a number of workers have begun to examine the functionalshortcomings of problem solving carried out by defectives and some of thiswork has been reviewed by O'Connor (1958). Annett (1957) showed how taskscontaining stimulus information of one and two bits could be solved withrelative efficiency by defectives but that an increase in information load led toa sharp differentiation between groups of above and below I.Q. 50. Thompson& Magaret (1947) demonstrated that hand-eye co-ordination was little affectedby mental handicap when compared with other subtests of the Binet in whichmanipulation of symbolic processes or span of attention was involved.Researches carried out by McCulloch et al. (1955) and Sloan & Berg (1957)show that symbolic, in this case word, learning is correlated with I.Q. so faras starting level is concerned, although gain over starting level may not be.

Although some studies show learning deficiencies to be associated with lowI.Q., others show improvements associated with long training independent ofintelligence level. The ways in which training techniques can be devised to

22 LEARNING IN IMBECILES

help the mentally handicapped to transcend deficiencies in a particular fieldof learning remains to be decided by further investigations. Barnett & Cantor(1957), for example, show ed that a transfer of set could take place in imbeciles.

In such studies the development of concepts is of primary importance, butconcept growth and the use of concepts by defectives of imbecile grade is littleunderstood. McPherson (1948) in her review of the literature showed thatexperiments in this area up to that date had been methodologically inadequate..The study reported here attempts to establish whether or not defectives ofimbecile grade can use simple concepts in problem solving. In addition thepossibility of the development of "learning sets" as used by Harlow (1949) foran improvement between tasks, as distinct from an improvement between trialson the same task, is considered.

METHOD AND MATERIAL

Procedure was based on an experiment by Gentry, Kaplan & Iscoe (1956)who compared monkeys and children on different learning tasks. While onetask could be solved by rote memory only, the other could be dealt with by thatmethod, or by the recognition of a common element in certain presenteddesigns. It was found that all human subjects, in contrast to the monkeys inGentry's study were able to employ the "principle of solution" and thuseffectively facilitate the rate of learning.

In the present experiment 20 institutionalised male imbecile children, dividedinto two groups of 10, with mean CA 12.9 years, range 10.3—16.4, and meanI.Q. 40.7, range 28—50, acted as subjects. Of these 20, 9 had no recognisedclinical anomalies. Of the remaining 11, 5 showed physiological or biochemicalabnormalities, 2 were mongols and 4 were diagnosed epileptics with braindamage.*

The material consisted of 6 series of pictures, each series containing 12different simple black outline drawings. The pictures were presented in pairs,on a sliding tray, each pair containing one "correct" and one "incorrect"picture. A sweet was hidden in a small well under the correct picture so thatits choice was rewarded. Instructions to the children were to try to find thepicture under which the sweet was hidden. Each child was tested individually,and each of the 6 series containing 6 pairs of pictures each, was presented for20 trials. Before the tests started, each child was asked to name each picturedobject in order to assure his familiarity with the represented items. All subjectscould do this without difficulty.

* Information concerning these conditions was kindly supplied by Dr. J. M. Crawfordand Dr. G. Dutton of Botleys Park Hospital.

BEATE HERMELIN AND N. O'CONNOR 23

The material fell into three categories, each represented by two series (Ia,Ib, Ila, l ib. Il ia, Illb). In Ia and Ib the correct pictures were arbitrarilychosen and could consequently only be learned and remembered by a processof rote memory. In Ila and l ib the concept to be generalised was that of anobject belonging to a certain class, the rewarded picture of a pair always show-ing "a piece of furniture" in Ila, and "an animal" in l ib. In the last categorya more abstract concept of quantity had to be evolved, and "three objects of akind" in series l l l a and "more than one object" in I l lb were pictured on thereward card.* The position of the rewarded card in a pair was varied randomlyfrom trial to trial. While one group of 10 subjects was presented with thematerial in order :

1. Rote material (Ia, Ib)2. "Concrete concept" ( I Ia= "furniture", IIb = "animals")3. "Abstract concept" (IIIa = "three of a kind", IIIb="more than one")

The other group was given1. Abstract concepts (Ilia, Illb)2. Concrete concepts (Ila, lib)3. Rote material (Ia, I b)

Thus, while the order of presenting two instances of related concepts "a" and"b" within each kind of material was maintained, order of presentation betweendifferent kinds of material was reversed for the second group. It seemedjustified to expect that this simple experimental design would give us an indi-cation of whether or not imbeciles could learn to use principles of classificationunder the stated stimulus conditions.

RESULTS

The results indicate that the subjects employed simple principles of classi-fication effectively enough to facilitate rates of discrimination learning. Meanscores for the number of trials at which the subjects reached and maintainedthe maximum score of 6 are given in Table 1. If a series had not been learnedafter 20 trials a score of 21 was assumed.

* The hypothesis that concepts of quantity and number represent a more abstract levelof concept attainment than concepts of concrete objects was based on experiments byHeidbreder (1946). She found that concepts evolve in a regular, consistent order, conceptsfor concrete objects evolving first and those relating to quantity and number last.Recognition for the former required a greater number of presentations than for thelatter. For the attainment of the latter, according to Heidbreder the subject has to importsymbols from outside the direct stimulus-situation which are not contained in the percept.In this sense such concepts are "abstract", as they require a departure from the givenpercept.

24 LEARNING IN IMBECILES

Significant differences in the rate of learning exist between concept and roteseries in both groups. The difference between concepts and following or pre-ceding rote material is significant at the 0.01 level for group 1 and the 0.02level for group 2. The learning curves of the mean number of correct responseson any trial for the different types of material show different characteristics—curves for rote material rise gradually, and straight lines can be fitted to them.For concept material on the other hand all curves but one show a sharp initialrise, the exception being one with an unusually high starting point in thisparticular series. Thus it seems justified to conclude that the quality of thelearning process has been different in the two instances.

Table 1

Number of trials needed to reach and maintain maximum correct scores

Material Rote Concrete Concepts Abstract Concepts(Ia) [Ib) (Ila) (lib) (Ilia) [Illb)

GROUP 1

Order of presentation . 1 2 3 4 5 6Mean 18.8 17.1 12.5 11.1 9.5 6.3S.D 2.64 4.23 4.80 5.99 5.79 4.63

GROUP 2

Order of presentation . 5 6 3 4 1 2Mean 17.8 16.9 10.3 11.0 12.9 5.4S.D 2.14 2.12 4.91 5.74 5.56 5.83

The position of any one task in the series does not significantly alter thespeed with which it is learned, while, as can be seen from Table 2, irrespectiveof its position, concept material is always learned in fewer trials than rote.Therefore, it seemed justified to treat the two groups as one in investigatingpossible transfer effects. Transfer is not apparent between different types ofmaterial. Also, if we compare the tasks within each group, i.e. Ia with Ib,Ila with l ib and I l ia with Il lb, there is no significant difference between thetwo rote series (Ia and Ib), nor between the two series representing "concrete"concepts (Ila and lib). There is, however, a difference between the two abstractconcept series (Ilia and Illb). The scores in the second abstract concept series(Illb) are the lowest for any material, which seems to indicate that the subjectshad the least difficulty with a task which, in Heidbreder's experiments, repre-sents the most abstract and difficult kind of concept. Significant transfer effects,as measured by correct number of responses on second trials in series I l ia andI l lb are evident between those two series.

BEATE HERMELIN AND N. O'CONNOR 25

Table 2

Differences within groups in number of trials needed to learn concept and rotematerial

Material Test No. t pGROUP 1

Rote 2 4.27 0.01Concrete Concept . 3

GROUP 2

Concrete Concept . 4 2.96 0.02Rote 5

Of the 20 children 15 spontaneously named the illustrated objects in any oneseries as soon as they had memorised the correct discrimination response. Oncenaming in this manner had commenced correct responses were maintained by13 out of the 15 subjects. Only 2 of the 20 children could, however, accountverbally for the principle according to which they made their choices. Theother 18 were quite unable, even on insistent questioning, to'fonnulate theprinciple, according to which correct responses had occurred.

The reported results deal \yith the difference between rote and conceptmaterial. However, both types of learning are affected by the differences inI.Q. between the subjects, as might have been expected. The rank correlationis 0.545 between the Terman-Merrill I.Q. and the mean number of trialsrequired to reach the criterion for all tasks combined.

As a result of dividing the subjects by diagnosis an interesting relationshipbetween intelligence level and detectable pathological condition becomesapparent. Those with physiological or biochemical anomalies had I.Q.s below40 in 8 of the 11 cases and those without had I.Q.s above 40 in 7 of the 9 cases.Fisher's exact probability measure gives a 0.006 level of significance for thisrelationship.

No significant relationship, however, was found between diagnosis and learn-ing ability, as measured by the number of trials needed by the subjects tolearn any one task.

DISCUSSION

In this experiment findings fall into two parts, those concerning the use ofconcepts and those concerning the transfer of learning sets. Regarding the first,it seems clearly indicated by the present experiment that imbecile children areable to use simple concepts as principles of solution, yet their ability to classifyand take note of essential similarities is relatively divorced from their abilityto formulate such principles verbally.

26 LEARNING IN IMBECILES

Hull (1920) reports that "mentally abnormals" show an almost completeinability to define a concept and that even with normals the ability to defineis not necessarily a true index of a concept's functional value. Verplanck(personal communication) obtained a similar indication from card-sortingexperiments with normal adults and children. On the other hand, investigationsreported by Luria (1956) and experiments such as the one by Spiker, Gerynoy& Shepard (1956) seem to suggest that verbal definition assists the attainmentof a concept. The extent and limit of the "conceptualising ability" of imbeciles,as well as the role which language could play to assist and further it, wouldhave to be determined by further experiments.

The appearance of a "learning set" in the "concrete concept" series was noteffectively different from practice effect with rote material. However, in thecase of I l ia and I l lb material, some transfer is apparent. Although "learningto learn", to use Harlow's term, was not demonstrated in all instances it didappear in this one set of material. Further experiments are, therefore, neededto determine those conditions under which transfer does occur as distinct fromthose under which it does not. .\

The individual differences shown in the results need fuller treatment andfurther investigation. They show the tendency of the presence of physiologicaland biochemical anomalies to affect I.Q. level but they also seem to show thatsuch anomalies do not affect learning significantly in this experiment.

SUMMARY

Twenty imbecile children were presented with 6 different discriminationtasks. While some of these could be learned by the use of rote memory only,others could be solved more effectively by the application of a generalisingprinciple. It was found that the subjects learned the concept series in signifi-cantly fewer trials than the rote series, thus indicating that they made effectiveuse of simple classifying concepts. "Learning sets" seemed to be operative inone of the two related concept categories.

ACKNOWLEDGMENT

The authors are indebted to Dr. J. M. Crawford, Physician Superintendentof Botleys Park, and his staff who kindly provided facilities for the researchreported here.

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