Producing generative sentence usage by imitation and reinforcement procedures.

Three retarded subjects and two developmentally normal toddlers were trained using imitation and reinforcement procedures to use correct sentences. The experimental task was to use sentences with correct subject-verb agreement to describe pictures that were presented to the subjects. Two classes of sentences were taught: those involving a plural subject that required the use of the verb "are" (for example, "the boys are running") and those involving a singular subject that required the use of the verb "is" (for example, "the boy is running"). The basic design of the study involved multiple baselines for each class of sentences. Four of the subjects began to produce novel, untrained sentences of a particular type to generalization probe pictures when that particular class of sentence was currently being trained. Thus, the imitation and reinforcement procedures appeared to be functional in producing generative sentence usage for both types of sentences. One subject produced correct sentences to both singular and plural probe pictures when only "is" sentences had been taught. A reversal procedure and retraining phase indicated that for this subject, imitation and reinforcement procedures for training one class of sentence behavior seemed functional in producing generative responses of the other class of sentences.