Behavioural Psychotherapy, 1990, 18, 207-219

Teaching Age and Gender Discriminationby the Enhancement of Criterion-relatedCues

Jon C. Reading* Department of Psychology,Central Hospital,

Hatton, South Warwickshireand Alastair K. Agerf Department of Psychology,

University of Leicester,Leicester

Teaching procedures encouraging the "errorless" acquisition of discriminationsthrough the enhancement of criterion-related cues have proved popular andeffective in work with individuals with severe learning difficulties. To date,however, their application has primarily been restricted to the learning ofrelatively simple discriminations, such as size and colour. The present studydescribes the successful implementation using two adults with severe learningdifficulties of a teaching programme adopting this approach with respect to theskills of age and gender discrimination. Along with encouraging generalizationand maintenance data, this success suggests that procedures involving theenhancement of criterion-related cues may have utility with a far broader range oftasks than previously considered.

Introduction

Recent years have seen continued interest in the use of errorless learning procedures inwork with individuals with severe learning difficulties (e.g. Schilmoeller and Etzel,1977; Jones and Culien, 1980; Lambert, 1980; Tennant etal., 1981; Richmond andBell, 1983; Ager, 1986; Strand and Morris, 1988). Whilst the exact form ofprocedure which is adopted varies considerably between studies, "errorless"approaches are characterized by an incremental adjustment of task features, generallymade in line with an individul learner's performance (Ager, 1986). A discriminationwithin the repertoire of an individual is initially presented, and this task is thentransformed in a step-wise fashion to that of the task to be taught.

* All correspondence should be directed to the first author. Preparation of this paper wassupported in part by a grant from the North Warwickshire Health Authority.

t Currently Senior Lecturer in Psychology, Chancellor College, University of Malawi, Box280, Zomba, Malawi.

0141-3473/90/030207 + 13 $03.00/0 © 1990 British Association for Behavioural Psychotherapy

208 Clinical section

The benefit of such procedures has been related to the manner in which theyencourage gradual shifts in the stimuli controlling response (Terrace, 1966; Ray andSidman, 1970). With teaching involving the manipulation of those stimuli known topresently control a response ("following the contours of existing control", Ray andSidman, 1970), the progress of learning may—in principle—be both measured andcontrolled rather more reliably than with traditional teaching approaches (Lambert,1980).

Given this rationale it is perhaps not surprising that more recent studies haveemphasized the value of building upon an existing discrimination related in sometangible fashion to the targeted discrimination. The earliest studies generally soughtto establish appropriate discriminative responses by gradually superimposing targetstimuli on a well-established—but totally unrelated—discriminative response (forexample, superimposing words onto cards of distinct colour). Breakdown ofresponding during the fading of stimuli associated within the existing discriminationwas, however, a common failing of such procedures (Etzel and Leblanc, 1979; Jonesand Cullen, 1980). In part, at least, this seems a consequence of such proceduresdemanding that a learner simultaneously attend to two stimulus dimensions, whenlimited breadth of attention is known to be a major factor associated with severelearning difficulty (Zeaman and House, 1963).

The literature now clearly supports the efficacy of building upon a topographicallyrelated discrimination, and certainly one involving the same stimulus modality (seeAger, 1983^; Strand and Morris, 1988). Further, there is mounting evidence that themost effective means of establishing errorless learning of a discrimination is to notrequire any transfer of control from one set of stimuli to another. Rather thanestablishing correct responding by building upon a discrimination already within therepertoire of an individual, the discriminability of the target stimuli themselves isenhanced to the point where correct responding is swiftly acquired. Teaching theninvolves the step-wise return of these stimuli to target conditions. A number of studiesnow suggest that the use of criterion-related cues (Schilmoeller and Etzel, 1977) inthis fashion can circumvent may of the difficulties previously associated with errorlessprocedures.

Despite this promising literature, the impact of errorless procedures whichmanipulate the discriminability of criterion-related stimuli has been somewhatlimited. The technology is well advanced for simple discrimination tasks involvingone-dimensional stimuli (such as colour, size and shape). To date, however, it hasseldom been applied to the teaching of more complex discriminations. Therefore,there must remain the suspicion that its utility may prove to be restricted to a smallrange of tasks peculiar in lending themselves to the identification (and enhancement)of criterion-related cues.

The purpose of the present study was thus to investigate the utility ofa procedure manipulating the discriminability of criterion-related cues with discrim-ination tasks of somewhat greater complexity than commonly examined previously.The skills of age and gender discrimination, as investigated here, may beconsidered to extend the complexity of discriminations investigated in at least twotespects.

Clinical section 209

Firstly, selecting which of two individuals depicted is "older", for instance, is arelative, rather than absolute, judgement. An individual may be older than the childwith which they are paired on one trial, but younger than the person with which theyare paired subsequently. The discrimination required by the student is thus aconditional one, depending on the context of that particular trial. Most previousresearch into procedures manipulating the discriminability of stimuli has involved theteaching of absolute discriminations (e.g. Rincover, 1978; Jones and Cullen, 1980).

Secondly, the cues underlying discrimination of age and gender are subtle,interactive and inconsistent in their occurrence (see Katcher, 1955). The existence ofmultiple cues may initially appear to make learning a discrimination easier (Zeamanand House, 1963). However, this holds only when an individual may respond reliablyby focusing arbitrarily on any one of the available cues. Where a judgement needs to bemade in relation to the aggregate of a number of cues (such as body shape, skin tone,hair colour/style, clothing etc. etc.) the multiplicity of cues may prove a difficultyrather than a benefit. Previous research in this area has focused almost exclusively ontasks where there is a single clearly-specifiable criterion-related cue which is consist-ently present across trials (e.g. Ager, 1986; Strand and Morris, 1988).

The present study therefore aimed to extend the generality of errorless learningprocedures based on the manipulation of the discriminability of criterion-related cuesby examining their application in teaching age and gender discrimination. The studythereby sought to clarify whether the principle of enhancing the discriminability oftarget stimuli would lead to the effective acquisition of a discrimination when (i) therequired discrimination involved a relative rather than absolute judgement and (ii) thecues underlying the discrimination were subtle, interactive and inconsistent in theiroccurrence.

Method

Subjects

The subjects for the study were two women with severe learning difficulties (MN andMY) who attended a state-run Social Education Centre full-time for occupation andtraining. Demographic and basic data regarding the subjects is given in Table 1.

TABLE 1. Demographic and basic psychometric data regarding the two subjectsparticipating in the study

Subject Age Sex Diagnosis Social age I.Q.

MN 40-9 yrs Female Down's Syndrome 3'7 yrs < 30 (below norms)(Vineland) (Stanford-Binet)

MY 19"0 yrs Female Hydrocephalus 5-5 yrs <30 (below norms)(Vineland) (Stanford-Binet)

210 Clinical section

Individual programme plans had identified receptive understanding of language asa focus for training with both women. Both subjects could follow instructionsregarding simple, concrete concepts (e.g. "give me the book", "show me the bigspoon" etc.), but experienced difficulty with more abstract or conditional concepts,MN had expressive speech at the level of two- and three-word utterances. SubjectMY's expression included full sentences, but these were often echolalic in nature andsituationally inappropriate.

Materials and design

Materials for the study consisted of sets of cards, each measuring approximately 20 cmby 15 cm. Each card had mounted upon it a colour photograph of a person, with theage and gender of the person depicted varying across cards.

Age discrimination materials consisted of two sets often cards. Each set depicted arange of ages—from infancy to old age. The gender of people depicted by thesematerials was balanced across the age range. Within each set, cards were numberedfrom 1 to 10 in order of ascending age.

Gender discrimination materials were prepared in a broadly similar fashion. Tworaters independently ranked a series of colour photographs of men and women formale:female cue dominance. Omitting all photographs where raters were not in 100%agreement, two sets often cards were produced, each comprising five photographs ofmen and five of women. Within each set, cards were numbered from 1 to 10 inascending order of malerfemale cue dominance (with card 1 thus representing thephotograph including the most female gender cues and card 10 that including themost male gender cues).

In total, therefore, four sets often cards were prepared; two depicting a continuumof age and two depicting a continuum of gender cue dominance (or perhaps moreproperly in this latter case, two adjacent continua of female gender cue strength andmale gender cue strength respectively). One set of age discrimination cards and one setof gender discrimination cards were set aside for generalization testing. The remainingsets were used as the materials for baseline assessment and training.

The numerical separation of two cards provided an approximate index of theirdiscriminability with regard to age or gender cues. Sub-sets of these cards could thusbe compiled in a manner which defined a series of "levels" of discriminability, thisbeing the variable that was manipulated during the course of training.

With regard to age discrimination training, nine levels of discriminability weredefined. Level 9 consisted of the presentation of only the two extremes of the agecontinuum—that is, the maximally discriminable cards 1 and 10. Level 8 involved thehalving of this minimum numerical separation with the presentation of cards from thesub-set, 1, 6 and 10. In a step-wise manner, subsequent levels involved thepresentation of cards from an increasingly large sub-set, until at level 1 the whole set ofcards was used for training. With the growth of the sub-set from which cards wereselected for training, the discriminability of presented stimuli was thus graduallydecreased. Table 2 shows the sub-set of cards used at each level of age discriminationtraining.

Clinical section 2 1 1

TABLE 2. Cards used at each discriminabilitylevel of age discrimination training

Level

987654321

Cards

1, 101, 6,1, 4,1, 3,1, 2,1, 2,1, 2,1, 3,1, 2,

107,6,4,3343,

108,6,

4,

108,77

65,

10987

6,

109, 108, 9, 107, 8, 9, 10

For gender discrimination training there were just five distinct levels of stimulusdiscriminability. Level 5 now involved the presentation of the maximally discrimin-able stimuli of cards 1 and 10. At level 4, cards 2 and 9 were introduced, andpresentation was of either card 1 or 2 with either card 9 or 10. In a step-wise manner,subsequent levels involved the introduction of an increasingly broad range of cards,and a resultant decrease in the discriminability of presented stimuli (see Table 3).

TABLE 3. Cards used at each discriminabilitylevel of gender discrimination training

Level Cards

5 1 vs. 104 1 or 2 vs. 9 or 103 1, 2 or 3 vs. 8, 9 or 102 1, 2, 3 or 4 vs. 7, 8, 9, or 101 1, 2, 3 ,4 , or 5 vs. 6, 7, 8, 9 or 10

The structuring of materials in this manner allowed an examination of the benefits ofenhancing the discriminability of criterion-related cues on the acquisition of thetargeted discriminations. The simultaneous teaching of two discriminations per-mitted the staggered introduction of such enhanced discriminability, providing ameans of controlling for the influence of extra-experimental effects on performance(Hersen and Barlow, 1976). Thus whilst an enhanced discriminability (ED) procedurewas adopted from the start of gender discrimination training, for the first five sessionsof age discrimination training a control procedure involving no enhancement ofstimulus discriminability was adopted.

212 Clinical section

Procedure

The basic procedure for presenting materials to subjects was the same across baselineassessment, training and generalization testing sessions. Cards were presented inpairs, being placed side-by-side on the table directly in front of the subject. Attentionto the materials was prompted, if necessary, by saying the subject's name—and thediscriminative command was then given. In the case of age discrimination trials thecommand was "show me who's older" \ for gender discrimination trials the command"show me the man" was given. The first card subsequently touched by the subject wasrecorded as the response for that trial. If no such response was made withinapproximately 10 s the command was repeated, a cycle which was continued—asnecessary—until a response was made.

Baseline

Baseline assessment comprised a total of 10 trials with both age and genderdiscrimination materials. The full range of discriminability of stimuli was sampled bypresenting together cards 1 and 10, 2 and 9, 3 and 8, 4 and 7, and 5 and 6. The orderof such presentations was randomized, as was the left—right positioning of presentedcards. As befits a baseline assessment of discriminative control (Ray and Sidman,1970) responding was maintained using a schedule of non-contingent reinforcement(i.e. subjects received verbal praise and/or physical encouragement irrespective of theirresponse).

Training

Training sessions comprised 15 trials of gender discrimination training, followed by15 trials of age discrimination training. For both subjects gender discriminationtraining began at level 9, that is with maximally discriminable stimuli. If correctresponding was at 80% or above over the first session, the subsequent session involvedpresentation of stimuli at level 8. In this manner the criterion of 80% success was usedto control the progress of the Enhanced Discriminability (ED) procedure through thevarious levels of stimulus presentation. When successfully attaining each criterion,the discriminability of stimuli was incrementally decreased; when failing to reachcriterion, the discriminability of stimuli was incrementally /Vzcreased.

Across the 15 trials of an age or gender discrimination training session the numberof presentations of each card within the relevant sub-set was balanced, as was theleft-right positioning of cards. Correct responses were praised verbally, a reinforcerwhich was "backed-up" periodically with applause and physical affection. Incorrectresponses were consequated with a stern "no" and modelling of the appropriateresponse.

Training took place over a period of 6 weeks, with sessions being conducted (onaverage) on four of the five working days of each week. Training continued for bothsubjects until in each case the ED procedure had led to subjects being exposed to thefull card sets (i.e. material at discriminability level 1) for at least two sessions.

Clinical section 213

Generalization

On the completion of training, subjects received a generalization test. Having beenexposed to numerous training sessions with the same two sets of cards, it wasimportant to consider whether the discriminations regarding age and/or gender whichappeared appropriate were, in fact, being maintained by task irrelevant features whichhappened to co-vary with relevant features (e.g. colour of clothes, marks on the cards'backgrounds). The two sets of cards which had been prepared in a like manner to thematerial used for training, but had not previously been seen by subjects, were thusused to test generalization of discriminative responding to novel age and gendercontinua. Presentation was identical to that used during training sessions save the factthat a schedule of non-contingent reinforcement was adopted (as at baseline) as befitsthe requirements of a generalization test (Ray and Sidman, 1970). The complete rangeof cards was used, with discriminative difficulty thus equivalent to a level 1 trainingtrial.

In order to determine the durability of training effects 6 months after thetermination of training, follow-up data was collected with regard to both the originalage and gender card sets and those used in the initial generalization test. Fifteen trialswere presented to each subject with each set of cards. The complete range of cards wereagain used, with discriminative difficulty thus equivalent to a level 1 training trial.

Results

The general progress of training is depicted in Figures 1 and 2 for subject MN, and inFigures 3 and 4 for subject MY. These figures allow detailed consideration of theestablishment and maintenance of control, not only by criterion-related cues, but also

• — • Correct responses• — • Position bias

B I 2 3 4 5 6 7 8 9 10 II 12 13 14 15 16 17 18 19 20 21 22 GSession

FIGURE 1. Progress of gender discrimination training for subject MN.

214 Clinical section

• — • Correct responses• — • Position biasA — • Gender bias

B I 2 3 4 5 6 7 8 9 10 II 12 13 14 15 16 17 18 19 20 21 22 GSession

FIGURE 2. Progress of age discrimination training for subject MN.

by certain task irrelevant cues which have been found to disrupt learning in two-choicediscrimination tasks (see Sidman and Stoddard, 1966; Ager, 1983a).

Overall trends

At baseline, subjects scored only marginally above the "chance" level on both age andgender discrimination, denoting no statistically significant control by age and gender

I — • Correct responses• — • Position bias

« 2

76

I 5

tn ^

I 3

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\^ \

^-4-9 \ / \ / \ / .

B I 2 3 4 5 6 7 8 9 10 II 12 13 14 15 16 17 18 19 20 21 22 G

Session

FIGURE 3. Progress of gender discrimination training for subject MY.

100 Ti

80 °

60 |

40 §

20 °-

0

Clinical section 215

12 13 14 15 16 17 18 19 20 21 22 G

• — B = correct response• — • = position bias and• — A - gender bias

FIGURE 4. Progress of age discrimination training for subject MY.

cues (60%, NS, Proportional Significance Test (PST), Bruning and Kintz, 1968).Following the introduction of the ED procedure, progress to level 1 of discrimi-

native difficulty was in every case made within 15 sessions, and in three cases out offour (excepting age discrimination training with MN) led to the significant control bytask appropriate stimuli with such minimally discriminable material (80% + , P <0-05, PST).

Attributing this progress to the use of enhanced discriminability of criterion-related cues—rather than non-specific training effects—is supported by the discon-tinuity in subjects' performance on the introduction of the ED procedure in session 6 ofage discrimination training. Whilst in session 3 subject MN had performed at a levelindicative of control by criterion-related stimuli (80%, P < 0-05, PST), indicatingthat some learning had taken place during SD sessions, neither subject displayedconsistent progress during this phase of training. On the introduction of the EDprocedure, however, significant appropriate control was immediately established forboth MN and MY (100% and 93% respectively, P < 0-01, PST).

Generalization testing following the termination of ED training indicated signi-ficant control by criterion-related cues for both subjects on both tasks (87%, P < 0-01and 80%, P < 0*05 for gender and age discrimination respectively, for each subject,PST).

With the exception of age discrimination by subject MY using generalizationmaterials (where responding narrowly failed to reach a level statistically above"chance"), in all cases, significant control by criterion-related cues was indicated at 6month follow-up (see Table 4).

216 Clinical section

TABLE 4. Percentage correct responding at 6 month follow-up. (Statistical analysis: Propor-tional Significance Test (PST), Bruning and Kintz, 1968)

Subject

MN

MY

Original

Gender

100%P < 0-01

86%P < 0-01

card set

Age

86%P < 0-01

93%P < 0-01

Generali

Gender

93%P < 0-01

80%P < 0-05

zation card set

Age

80%P < 0-05

73%NS

Overall, therefore, the data supports the utility of the ED procedure as a means ofestablishing appropriate stimulus control of relatively complex discriminations. Thegeneralization data are particularly encouraging, as they suggest that the EDprocedure served to establish control by genuine age and gender related cues ratherthan incidental, task irrelevant stimuli covarying with such cues. The results atfollow-up are also encouraging because, in general, they imply that the ED proceduremay produce lasting and robust effects.

Analysis of shifts in control

Examining the figures individually allows insight into the shifts in discriminativecontrol which occurred during training, and suggests how such shifts may be relatedto the manipulation of stimulus discriminability. Each figure plots the degree ofposition response bias evident within each session, and Figures 2 and 4 also plot genderresponse bias. Response bias data are calculated by considering the excess of responsesconsistent with choice of a particular stimulus position (or gender) compared with theresponse profile which would result if choices had been made in direct proportion tothe number of times that choice was available. A measure of the discriminative controlexerted by position (or gender) cues is thus provided. (Age bias data during genderdiscrimination training is not plotted, as there was considerable homogeneity of ageacross gender discrimination material).

In this manner Figure 1 shows how for gender discrimination training withsubject MN, the lack of appropriate control by gender cues at baseline was accom-panied by a considerable position bias in her responding. On the introduction of theED procedure, however, control by appropriate cues was immediately established andthe position bias eliminated. As the ED procedure continued in subsequent sessionsstimulus discriminability was steadily reduced. This led, however, to a gfadualweakening of appropriate control and eventual reestablishment of the position bias. Bysession 6 this had reached its baseline level, but with significant appropriate controlstill just indicated (80% correct) the level of discriminability of stimuli (now at level 1)was not increased. Rather than a further decline in performance, however, the nextsession produced 100% success for the first time and a total elimination of the positionresponse bias. Subsequently, performance remained at a high level, though small

Clinical section 217

decrements were usually associated with some degree of position bias. Here then is apicture of the successful establishment of discriminative control, where nonethelesssuch control may be seen as being a somewhat unstable phenomenon—with compet-ing sources of control periodically reemerging when criterion-related cues are noteasily discriminable.

The course of gender discrimination training for MY (depicted in Figure 3)followed a similar pattern. There is a general synchrony of the weakening ofappropriate control and the strengthening of position bias, though the direction of anycausal link can only be surmised. For both MN and MY, however, it is clear that theED procedure—in responding to the loss of appropriate control by increasing thediscriminability of stimuli—was in such circumstances effective in reestablishingcontrol by criterion-related cues.

In plotting two sources of competing control, Figures 2 and 4 (depicting theprogress of age discrimination training for MN and MY respectively) allow a still moredetailed analysis. For both subjects, baseline and the first five sessions of training(involving no enhancement of discriminability) were characterized by fluctuationbetween various sources of control. The first ED session led however, in each case, tothe establishment of appropriate responding. This session used cards (1 and 10)maximally discriminable with regards to age cues, but by depicting arT elderly man anda baby girl such responding was also consistent with control by gender cues. With thesubsequent presentation of less discriminable material (where the cues of age andgender were not confounded) it is clear that it was, in fact, age cues that were exertingsignificant control of responding. For both subjects, though, the subsequent progressof training was marked—as with gender discrimination training—by the periodicweakening of appropriate control and the development of bias toward other sources ofcontrol. In such circumstances, however, the increased discriminability of stimulipresented due to the operation of the reactive ED procedure resulted in the re-establishment of appropriate control, and indeed the establishment of such controlwith increasingly less discriminable stimuli.

Examining the shifts in stimulus control during training in the above manner thusgives some indication of the means by which the ED procedure was effective inteaching age and gender discrimination to the two subjects of the study. It is clear thatdiscriminations were not acquired in a steady and incremental fashion, but ratherinvolved a complex interplay of competing sources of control. For subject MY, inparticular, responding to positional cues appeared to be a strong repertoire whichre-emerged frequently. However, the reactivity of the ED procedure meant that thesaliency of criterion-related cues was swiftly increased whenever such inappropriatecontrol was in evidence. Increasing the perceptual saliency of criterion-related cues byenhancing their discriminability consistently proved effective in establishing controlby such cues.

General discussion

In the terms considered earlier, the results of this study commend the potential utilityof a teaching procedure involving manipulation of the discriminability of criterion-

218 Clinical section

related cues in circumstances where (i) the required discrimination involves a relativerather than absolute judgement, and (ii) the cues underlying the discrimination aresubtle, interactive and inconsistent in their occurrence. This represents a significantextension of the use of this form of errorless teaching procedure, and suggests that itsapplicability may extend well beyond the teaching of simple discriminations—thefield to which it has generally been limited to date.

In the present study, the ED procedure consistently led to a rapid acquisition ofappropriate discriminative control, with discriminative performance both generaliz-ing across stimulus material and being maintained over time. These generalizationand maintenance data are encouraging, particularly given the general dearth of suchfindings in the literature on the durability of training effects (Ager, 1987).

Notwithstanding all this, the experimental design adopted here does not allow astraightforward comparison of the relative effectiveness of the enhanced discrimin-ability procedure and a teaching approach using a full range of stimuli throughouttraining [in terms of Lambert (1980), a "trial-and-error" procedure]. Whilst theefficacy of the former is clearly suggested, there is likely to be no substitute for directcomparative studies of such differing teaching approaches. The possibility of using cueenhancement as an adjunct, rather than alternative, to other teaching approaches alsomerits consideration.

The use of procedures enhancing the discriminability of criterion-related cues thusclearly warrants further investigation—especially in relation to the teaching of morecomplex discriminations. In this regard, data which allows the tracking of shifts instimulus control, as presented here, may prove particularly instructive. Such data mayclarify the manner in which such procedures prove effective, and thereby lead to boththeir refinement and extended application.

Finally, it is worth drawing attention to a feature of enhanced discriminabilityprocedures of the form described here which is potentially of major practicalsignificance. This is the manner in which such procedures provide a teachingprogramme which is subtle and individualized and yet, at the same time, readilygenerated with respect to a simple conceptual framework. In the study reported here,for instance, the enhanced discriminability procedure produced a responsiveindividually-tailored intervention which, nonetheless, followed a simple rule struc-ture and which therefore could have been implemented by a teacher or instructor withlittle specialized training. To the extent to that the procedures involve the a prioridefinition of the circumstances in which the goals of the task will be clarified and/or thedifficulty of the task reduced, they may be seen as a step in the direction where thesubtle analysis and adjustment of tasks made by good "intuitive" teachers (see Ager,1983^) may be operationalized for effective use by others.

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(Date received: 26 April 1989)