Date of Award


Degree Name

Master of Science


Behavior Analysis and Therapy

First Advisor

Heal, Nicole


The overjustification effect is commonly used as evidence in arguments made against using rewards with children. The purpose of this study was to extend the literature on the overjustification effect by using single-subject methodology and to assess the effects of relative preference between the instrumental task and the reward in the prediction of the overjustification effect. Two conditions were alternated in an alternating treatments design in which either a relatively higher or lower preferred reward was presented contingent on task engagement. Three patterns of responding were observed: the high preferred reward did not function as a reinforcer for any of the participants, a punishment effect was observed when a lower preferred reward was presented for one participant, and a reinforcement effect was observed when a lower preferred reward was provided for 2 of 3 participants. Evidence for the overjustification effect was only present following the punishment effect. Results are discussed in terms of potential explanations for the observed effects and suggestions for future research are provided.




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