William J. McIlvane

Teaching coin equivalences via matching to sample.

A moderately mentally retarded woman learned coin equivalences (with 5-, 10-, and 15-cent values) via matching to sample. When taught to match two different coin stimuli to a printed price of equal value, she could then match the coin stimuli to each other and state their values without further training. Additional coin-matching and naming performances emerged after establishing the equivalence between a new coin stimulus and one member of an existing class of equivalent stimuli. The study extends research on stimulus class formation by examining its usefulness in a new application, in teaching a skill repertoire that requires mastery of large numbers of individual performances-monetary equivalences. Further, the study suggests efficient strategies for teaching functional money skills to developmentally limited populations.

Stimulus class formation and functional equivalence in moderately retarded individuals' conditional discrimination

Three mentally retarded humans first acquired a simple discrimination: Simultaneously displayed visual stimuli A1 and A2 functioned as S+ and S-, respectively. The subjects also acquired a conditional discrimination, learning to select visual stimuli B1 and B2 conditionally upon A1 and A2, respectively. Then, B1 and B2 were displayed without A1 or A2. Subjects selected B1, an emergent discrimination that showed that B1 and B2 had become functionally equivalent to A1 and A2, respectively. Two subjects next learned to select C1 and C2 conditionally upon B1 and B2, respectively. They also learned to select B1 and B2 conditionally upon D1 and D2, respectively. Subsequent simple discrimination probe trials displayed (a) C1 and C2 and (b) D1 and D2. On the former, the subjects nearly always selected C1. On the latter, they initially selected D1 and D2 about equally often. Thus, the emergence of simple discrimination appears to depend on a specific experimental history.

An analysis of generalized identity matching-to-sample test procedures

This paper examines issues that must be considered when evaluating generalized identity matching to sample. We suggest that (a) stimuli displayed together on tests of generalized identity matching should have comparable experimental histories, and (b) identity matching procedures should be differentiated as either “conditional” or “nonconditional,” depending upon whether or not conditional discrimination is required. Although either type of procedure might be adequate for demonstrating a “matching concept,” we suggest that only generalized conditional identity matching provides an adequate test for the reflexive property of conditional relations.

Positive and Negative Stimulus Relations in Severely Retarded Individuals' Conditional Discrimination.

Abstract Four low-functioning mentally retarded subjects learned conditional discrimination performances in two-comparison auditory-visual and visual-visual identity matching-to-sample paradigms. Auditory stimuli were spoken food names and visual stimuli were food items. The subjects were also taught, by means of a stimulus shaping program, to perform a variant of the auditory-visual task in which only one comparison was displayed on each trial: if the correct one was displayed, to select it; if an incorrect one, to select a blank alternative. Following the program, subjects performed auditory-visual conditional discriminations on the basis of relations between either the sample and the correct comparison (positive relations) or the sample and the incorrect comparison (negative relations). Additional tests, conducted in the single comparison positive and negative relations (1) in auditory-visual performances with foods that had a two-comparison history, but had not been used in stimulus shaping, and (2) in visual-visual identity performances. All subjects proved capable of such performances. The results suggested that acquisition of both postive and negative conditional relations may occur when developmentally-limited individuals are trained with matching-to-sample procedures. This outcome may be relevant to designing remedial communication programs for this population—especially those concerning generalized “Yes”-“No” concepts.

Assessing same/different judgments in individuals with severe intellectual disabilities: A status report☆

This report summarizes state-of-the-art approaches for assessing visual stimulus same/different judgments in individuals with severe intellectual disabilities. Methods are described that permit one to conduct assessments on a population-wide basis, excluding few if any participants due to failure to acquire necessary baseline performances. Methodological investigations summarized here indicate that one can obtain reliable same/different judgments with a variety of stimuli in virtually anyone for whom a basal score on the Peabody Picture Vocabulary Test can be obtained. This approach includes judgments involving not only familiar, readily nameable stimuli, but also abstract two-dimensional forms of the type commonly used to minimize extraexperimental influences on performance. Taken together, recent findings lead to the conclusion that past studies have significantly under-estimated the capacity of participants with low MA scores to make same/different judgments. They also suggest a more general methodological approach that can potentially lead to more sensitive assessment of other behavioral capacities in this difficult-to-test population.

Spoken and signed naming of foods after receptive exclusion training in severe retardation

Two low-functioning mentally retarded subjects learned to name food items after receptive exclusion training, conducted as follows: The subjects first learned to select a small number of foods in a two-choice matching-to-sample task. For one subject, the samples were dictated names; for the other, the samples were manual signs. They also learned to name these known foods, either orally or by signing. On exclusion trials, a known food was displayed with a new food whose corresponding name or sign had not yet been learned, and a novel sample (spoken or signed), corresponding to the new food, was presented. The subjects typically selected the new food immediately, apparently by excluding the food related to the known sample. If a known sample was presented, however, the subjects continued to select the known food correctly. Periodically during exclusion training with a number of new foods, the subjects were tested for production of food names or signs. With few exceptions, the subjects produced the food names without direct training, often after only a few receptive exclusion trials. The results suggest strategies for teaching simple receptive and expressive relations to severely mentally retarded individuals.

Fast Mapping and Exclusion (Emergent Matching) in Developmental Language, Behavior Analysis, and Animal Cognition Research

Researchers from behavior analytic, developmental, and comparative perspectives have all investigated the conditions under which new arbitrary (symbolic) stimulus-stimulus relations are acquired. For example, young children, people with severe mental retardation, and several species of nonhuman mammals all exhibit emergent matching (EM) in the context of a wellestablished matching-to-sample baseline: When presented with an undefined sample stimulus and a comparison array that includes one undefined comparison and one or more baseline comparisons, participants select the undefined comparison. Further, subsequent testing may show a learning outcome: Exposure to EM trials may result in a new defined relation involving the formerly undefined stimuli. Between 1974 and the late 1980s, emergent matching and learning outcomes were described independently by behavior analytic, child language, and animal cognition researchers. Cross-literature citations were virtually absent, however. More recently, crossdisciplinary citations have begun to appear. This article briefly reviews the history of EM research, emphasizing the independent development of research programs, methods, and terminology in the three disciplines. We then identify several research areas where a multidisciplinary approach may benefit all concerned.

Some Observations on Control by Spoken Words in Children's Conditional Discrimination and Matching by Exclusion.

This study examined matching-to-sample procedures that might result in the emergence of conditional behavior never explicitly taught. Subjects were preschool children. Two pictures were displayed as comparisons on every trial, and samples were spoken words. In baseline training preceding each of three experiments, children learned to select pictures of a dog, a table, and a banana in response to their spoken English names. Thereafter, probe trials displayed novel comparisons with baseline comparisons: one novel comparison was displayed with the dog and another with the table. The three experiments differed primarily in the nature of the samples presented on probe trials. In Experiment 1, probe samples were novel words, JAIJAI and BREEL. On the probes, each of seven subjects reliably selected the novel comparisons, apparently excluding the familiar ones. In Experiment 2, probe samples were from the subjects baseline. On one probe, for example, the sample was TABLE, and the subject had to choose either the dog or the novel picture. Exclusion was logically possible because the dog had always before been incorrect in the presence of TABLE. Under these conditions, however, only two of nine children excluded reliably. In Experiment 3, probe samples were words that had never been samples on any matching-to-sample trial, but that had controlled the childrens behavior in other settings. On one probe, for example, the sample was PENCIL, and the subject had to choose either the dog or a novel picture. Subjects virtually always excluded the former and selected the latter. Unreliable exclusion in Experiment 2, therefore, apparently resulted because the probe samples had previously served also as samples on baseline trials. Spontaneous verbalizations recorded during probing provided further data consistent with this interpretation. The study helps to define variables controlling exclusion performances by showing that such performances are more likely to occur if the sample has no prior experimental history.

Generalized Identity Matching to Sample of Two-Dimensional Forms in Individuals with Intellectual Disabilities.

An assessment of identity matching to sample with two-dimensional forms was conducted with 44 subjects with moderate and severe intellectual disabilities. Identity matching that did not require conditional discriminative functions was tested first; subjects who passed that test were then tested on a conditional identity matching task. Tests for generalized identity matching were passed by 30 of the 44 subjects. The 14 individuals who did not pass were given a further teaching assessment that sought to teach identity matching directly via standard teaching methods. Some subjects also received training on a series of simple discriminations taught by the same methods. Four additional subjects passed identity matching tests. Overall, generalized identity matching was demonstrated in 34 of 44 subjects, including 7 of 16 individuals with mental age (MA) scores of 3.0 years and below and 14 of 15 individuals with MA scores between 3.0 and 5.0 years. Results with these two groups are much superior to those typically reported for individuals with comparable MA scores. The capacity for generalized performances requiring same/different judgments appears to have been substantially underestimated in this population, perhaps especially when the stimuli are two-dimensional, relatively abstract forms.

Teaching money skills through stimulus class formation, exclusion, and component matching methods: Three case studies

This paper describes novel methodology for teaching monetary skills to mentally retarded individuals. The goal of the methodology is to generate such skills with relatively little explicit training. To do so, the procedures were designed to produce emergent new behavior through stimulus class formation, exclusion, and matching of stimulus components. Three case studies demonstrate the methods and provide illustrative supporting data.