Identifying stimuli in the natural environment that control verbal responses.

When a learner is taught a new response, the stimuli that influence its display often are unknown. These stimuli alter the probability of occurrence of the response. That is, when they are present, the response occurs; when they are absent, it does not occur. By identifying the stimuli that influence the probability of newly acquired responses, interventionists may program for their generalization more effectively and efficiently. In the present study, 2 students who were moderately retarded were taught to label a coin. Eight environmental stimuli that were present during training were identified. The effect of each stimulus on the occurrence of the response was assessed prior to and after training by presenting the remaining seven stimuli and altering only the target stimulus. The results demonstrated that by altering one stimulus at a time, responding continued uninterrupted. For 1 of the 2 learners, however, responding was disrupted by altering two stimuli simultaneously. The implications of these findings are discussed in terms of stimulus control and generalization.