Teacher verbalizations and task performance with autistic children.

The purpose of this study was to investigate the effects of teacher verbalizations on the correct task performance of autistic children when positive reinforcement was presented in a noncontingent fixed-time schedule. Individual sessions were conducted using easy and difficult tasks with two autistic children. A within-subjects A-B-A-B withdrawal design was used. The results indicate that teacher verbalizations produced increases in the percentage of correct responding on difficult and easy tasks. This finding is discussed in terms of negative reinforcement and demand characteristics. The educational implications are also presented.