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Date of Award


Document Type

Thesis - Pacific Access Restricted

Degree Name

Master of Arts (M.A.)



First Advisor

John C. Borrero

First Committee Member

Kenneth Beauchamp

Second Committee Member

Carolynn Kohn

Third Committee Member

Roseann Hannon


We evaluated behavior exhibited by individuals with developmental disabilities using progressive ratio schedules. High- and low-preferred stimuli were determined based on the results of a paired-stimulus preference assessment and were evaluated in subsequent reinforcer and progressive ratio assessments using concurrent- and single-operant schedules of presentation in a modified reversal design. Results showed that for two participants, stimuli determined to be low-preferred via a preference assessment functioned as reinforcers when evaluated independently of high-preferred stimuli and under gradually increasing response requirements. The results suggest that for cases in which a high-preferred stimulus is unavailable or unfeasible, the contingent delivery of relatively less-preferred stimuli may maintain appropriate behavior, even as response effort is increased. In addition, results of the progressive ratio evaluation are suggestive of stimulus value.



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