Abstract
A mentally retarded subject was taught use of grammatically correct sentences, all of which included subjects, predicates, and objects. The particular sentence form 'which was used in training consisted of combining labels that had already been present in his repertorie. A systematic sequence of prompt and probe trials was used to teach a particular sentence form. During prompt trials the experimenter presented a picture and modeled the particular sentence form for the subiect to imitate, on probe trials the experimenter did not model. Correct responses to prompts were reinforced on the FR6 schedule and correct responses to probes were reinforced on a continuous reinforcement (CRF) schedule by chiming followed by a green 0 signal. Incorrect responses were punished by buzzing followed by a red X signal. A follow-up study was conducted for 3-18 weeks after the training ended. During Baseline 1, the subject could hardly use the correct sentence form. At Baseline 2 which came after the training ended, the subiect demonstrated a significant increase in percent correct during use of the sentence form. The increased percentage was maintained throughout the follow-up period and the response generalized to untrained and novel stimuli. The results of this study demonstrated that a complex verbal response could be trained in a mentally retarded child. The acquisition and retention of the use of grammatically correct sentences demonstrated that the training procedures, imitative prompting, and differential reinforcement were the crucial factors in the development of the response.
