Identifying stimuli that alter immediate and subsequent levels of vocal stereotypy: a further analysis of functionally matched stimulation.

We used a three-component multiple-schedule with a brief reversal design to evaluate the effects of structurally unmatched and matched stimuli on immediate and subsequent vocal stereotypy that was displayed by three children with autism spectrum disorders. For 2 of the 3 participants, access to matched stimuli, unmatched stimuli, and music decreased immediate levels of vocal stereotypy; however, with the exception of matched stimuli for one participant, none of the stimuli produced a clear abolishing operation for subsequent vocal stereotypy. That is, vocal stereotypy typically increased to baseline levels shortly after alternative stimulation was removed. Detection of motivating operations for each participant's vocal stereotypy was aided by the analysis of component distributions. The results are discussed in terms of immediate and subsequent effects of preferred stimuli on automatically reinforced problem behavior.