The authors evaluated the effects of matched and unmatched stimuli on immediate and subsequent engagement in targeted vocal stereotypy (Experiment 1) and untargeted motor stereotypy (Experiment 2). Results of Experiment 1 showed that (a) matched stimulation decreased immediate engagement in vocal stereotypy for 8 of 11 participants and increased subsequent engagement in vocal stereotypy for only 1 of the 8 participants and (b) unmatched stimulation decreased immediate engagement in vocal stereotypy for only 1 of 10 participants and did not increase subsequent engagement in vocal stereotypy for this participant. Results of Experiment 2 showed that for 8 of 14 participants, untargeted stereotypy increased when the matched or unmatched stimulus was present, after it was removed, or both. The authors briefly discuss the potential clinical implications of using matched stimulation to decrease vocal stereotypy and limitations of the findings.

We conducted five experiments to evaluate the predictive validity of a free-operant competing stimulus assessment (FOCSA). In Experiment 1, we showed that each participant's repetitive behavior persisted without social consequences. In Experiment 2, we used the FOCSA to identify high-preference, low-stereotypy (HP-LS) items for 11 participants and high-preference, high-stereotypy (HP-HS) items for nine participants. To validate the results of the FOCSAs (Experiment 3), we used a three-component multiple schedule to evaluate the immediate and subsequent effects of an HP-LS stimulus, an HP-HS stimulus, or both (in separate test sequences) on each participant's stereotypy. Results of Experiment 3 showed that the FOCSA correctly predicted the immediate effect of the HP-LS stimulus for 10 of 11 participants; however, the FOCSA predictions were less accurate for the HP-HS stimulus. Results of Experiment 4 showed that a differential reinforcement of other behavior procedure in which participants earned access to the HP-LS for omitting vocal stereotypy increased all five participants' latency to engaging in stereotypy; however, clinically significant omission durations were only achieved for one participant. Experiment 5 showed that differential reinforcement of alternative behavior in which participants earned access to the HP-LS stimulus contingent upon correct responses during discrete-trial training reduced targeted and nontargeted stereotypy and increased correct academic responding for all four participants. The potential utility of the FOCSA is discussed.