The effects of stimulation on the operant responses of children with attention/deficit hyperactivity disorder

A derivation of the optimal stimulation theory proposes that individuals with attention deficit/hyperactivity disorder require more or habituate more rapidly to stimulation than normal individuals. When given materials that are stimulating (e.g., colorful), individuals with AD/HD do not need to generate alternative sources of stimulation though, for example, body movement, which could interfere with performance on some assigned tasks. Previous researchers have presented stimulation antecedent to responses on tasks and could only speculate about the mechanism governing enhanced performance and reduced activity. The general purpose of these two studies was to determine the mechanism governing enhanced performance and decreased activity by (a) evaluating stimulation as a potential reinforcer, and (b) determining whether the effects of stimulation as a reinforcer are dependent upon the saliency of alternative sources of stimulation in the environment (i.e., competing stimulation). The purpose of the first study was to assess the effects of high and low within-task stimulation on performance and behavior using a simple addition task. Seventeen students with AD/HD were exposed to high within-task stimulation that was presented according to a variable-interval 15s schedule contingent upon task completion and consisted of a visually stimulating computer screen as background for the addition problems. Results showed that participants completed more problems and were less active in the high within-task stimulation condition. The purpose of the second study was to assess the effects of noncontingent competing stimulation on the performance and behavior of children with AD/HD using the same addition task with high within-task stimulation that resulted in enhanced performance and reduced activity levels in the first study. Seventeen students with AD/HD were exposed to high and low levels of competing stimulation. Competing stimulation consisted of cartoons presented on a second monitor located adjacent to the task monitor. Results showed that the participants completed fewer problems in the high competing stimulation condition. Overall, these studies demonstrated that within-task stimulation (a) can be used as a reinforcer, and (b) is effective only to the extent that it can complete with alternative sources of stimulation in the environment. The results provide additional support for a more contextual view of AD/HD