Author ORCID Identifier


Date of Award

Spring 5-1-2023

Degree Type


Degree Name

Doctor of Philosophy (PhD)



First Advisor

Michael J. Beran


A status quo bias is a tendency to resist change and keep things as they are. This bias is robust in humans and likely a byproduct of heuristic decision-making mechanisms, indicating that it may be an evolutionarily-conserved process that is phylogenetically widespread. However, few status quo bias studies have been conducted with nonhuman animals, and the evidence was mixed. Studying this question with animals could help inform welfare decisions for animals directly and it can shed light on the degree to which a status quo bias (as seen in humans) may be a result of human-unique experiences or the consequence of more fundamental decision-making mechanisms. The goal of this study was to explore whether other primates exhibit a preference for the status quo after controlling for reinforcement history, and to explore the relative influence of several different factors that may moderate the status quo bias effect. To test these questions, I conducted two experiments. In Experiment 1, capuchin monkeys and macaques made choices among computerized tasks, where one task was presented as the ‘default’ option (i.e., it could be played continuously without having to select it from a menu), after forced runs of trials that varied in length and which included trials of either a single task type or a mix of task types. I predicted that the monkeys would demonstrate a general preference for the default task over non- default alternatives, and that this preference would increase in magnitude after longer forced runs of the default task. In Experiment 2, lemurs and tamarins learned that boxes could be opened in two ways (lifting or sliding). I explored whether animals could be influenced to open the box by using one particular mechanism after recent exposure to that mechanism (i.e., establishing it as the ‘status quo’) while controlling overall reinforcement history for both mechanisms. The results indicated that the animals did not exhibit a status quo bias in these paradigms; other factors such as variety and task preference (E1) and approach angle (E2) had greater influence on animals’ choice behavior than the established status quo.


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