Comparison of reinforcement schedules in the reduction of stereotypy with supported routines

The rates and durations of stereotypic behaviors in four adolescents with severe mental retardation were measured during two daily vocational training sessions and during contiguous periods of leisure in their special education classrooms. Vocational training was conducted in two different tasks, alternating across days. The task requirements for each participant were matched to each participant's learning and performance characteristics. The participants were exposed to a fixed ratio schedule of tokens exchangeable for food items on one task and to a variable interval schedule for the same consequences on the second task. The schedules were chosen as an initial test of a matching-law based prediction by Myerson and Hale (1984): Variable interval reinforcement for adaptive behavior will produce less allocation of responding to maladaptive behavior than will a ratio-based intervention. When work performances stabilized, the schedules of token delivery were reversed across the tasks and performances again stabilized. Results are reported for periods when work performances met stability criteria. Stereotypy occurred more during leisure than during vocational training under either schedule. The major differences in stereotypy between leisure and vocational training were differences in episode length rather than rate of onset. Onset of stereotypy in vocational training, however, occurred at higher rates under the interval schedule than under the ratio schedule in both tasks. The results are discussed in terms of Myerson and Hale's prediction and implications for further research and application.