Positive and negative stimulus relations in severely retarded individuals′ conditional discrimination

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.