Effects of the Acquisition of Prerequisite Behavior on the Learning of Nonvocal Verbal Behavior and Vocal Imitation in Children With Severe Retardation

The effects of acquisition and maintenance of prerequisite interactions, such as attending behavior, nonverbal imitative behavior, and disruptive behavior, on the learning of nonvocal verbal behavior and vocal imitation were evaluated. Four severely retarded children were selected on the basis of low level or absence of the target behaviors (nonvocal verbal behavior and vocal imitation) and failure to reach the acquisition criterion on prerequisite behavior. The results were evaluated visually and by time series analysis. Findings indicated that the acquisition of prerequisite interactions led to superior performance and fewer trials to reach criteria in this language intervention.