Functional assessment and treatment of perseverative speech about restricted topics in an adolescent with Asperger syndrome.

A functional analysis showed that a 14-year-old boy with Asperger syndrome displayed perseverative speech (or "restricted interests") reinforced by attention. To promote appropriate speech in a turn-taking format, we implemented differential reinforcement (DR) of nonperseverative speech and DR of on-topic speech within a multiple schedule with stimuli that signaled the contingencies in effect and who was to select the topic. Both treatments reduced perseverative speech, but only DR of on-topic speech increased appropriate turn taking during conversation. Treatment effects were maintained when implemented by family members and novel therapists.