Date Approved
2021
Degree Type
Open Access Thesis
Degree Name
Master of Science (MS)
Department or School
Psychology
Committee Member
James Todd, Ph.D.
Committee Member
Rusty McIntyre, Ph.D.
Committee Member
Kenneth Rusiniak, Ph.D.
Abstract
The overjustification effect posits that rewards undermine intrinsic motivation, such that an individual’s engagement in previously intrinsically motivating tasks will decrease when a previously reliable reward is withdrawn. This study aimed to determine if this overjustification effect can be demonstrated in rats, with typical confounds related to social and verbal aspects of reward delivery controlled for. Baseline “intrinsic” wheel-running rates of seven SpragueDawley rats were compared to rates that followed administration and withdrawal of a contingent sucrose reward, and to rates of rats in control conditions (n = 7). Consistent with the author’s hypothesis, the reward group’s wheel-running did not decrease below the initial baseline following this procedure, as would be predicted by the overjustification hypothesis. This suggests that the overjustification effect demonstrated in humans may be better conceptualized as being related to social and verbal aspects of rewards rather than as an inherent feature of reward administration and withdrawal.
Recommended Citation
Sunde, Eleah, "An experimental analysis of the classic overjustification effect in rats: Does the removal of “expected” rewards alter behavior in rats as it does in humans?" (2021). Master's Theses and Doctoral Dissertations. 1086.
https://commons.emich.edu/theses/1086