Date of Award

Spring 5-10-2014

Degree Type


Degree Name

Master of Arts (MA)



First Advisor

Sarah F. Brosnan


Extensive evidence compiled over the past decade demonstrates that many species of animals respond negatively to inequity across several different contexts. One context that remains unexplored is whether inequity responses are influenced by the experimenter. Experimenter effects remain an enduring concern within animal research. I investigated whether the presence of the experimenter influences responses to inequity in a nonhuman primate species, the capuchin monkey (Cebus apella). In the presence or absence of an experimenter, monkeys worked in pairs to complete a computerized task, following which individuals received rewards that were either equal or unequal in comparison to the partner’s rewards. Monkeys had difficulty learning the task, but after learning, rates of refusals were influenced by the individual reward received rather than the social comparison or the actions of the experimenter. I consider reasons for their frustration with the task and their subsequent lack of an inequity response in this context.