Improving profoundly mentally retarded adults' performance on a position discrimination.

The relative importance of stimulus manipulations antecedent to or consequent on the response was investigated in three experiments related to position discrimination. In the first experiment, two different stimuli (either a piece of candy or a toy cat) were hidden under one of three boxes in full view of 2 profoundly mentally retarded adults. The behavior of uncovering the hidden object was measured using a combined multiple baseline and reversal design. In Experiment II, an entire unit of profoundly retarded adults was screened to determine the prevalence of the effects observed in Experiment I. In Experiment III, an attempt was made to determine whether the difference in antecedents (candy vs. kitty) or consequences accounted for the superior performance when the candy was hidden. In this experiment, using a reversal design with four profoundly retarded adults, we found that the antecedent manipulation (hiding the candy vs. hiding the toy cat) resulted in better performance than did the manipulation of the consequence (handing subjects the candy or allowing them to uncover and consume it).