Author ORCID Identifier

Date of Award


Degree Type


Degree Name

Master of Arts (MA)



First Advisor

Sarah F. Brosnan

Second Advisor

Michael Beran

Third Advisor

Kevin Swartout


Succeeding under high pressure is highly beneficial not only for humans, but also for

non-human animals. I studied a captive colony of socially-living tufted capuchin monkeys as a model species to examine performance failure (or “choking”) under pressure and to see if endogenous levels of hormones correlated with likelihood to fail under high pressure. I also explored if cortisol and testosterone interacted under non-competitive paradigms of stress. I found that capuchin monkeys differed significantly in reactions to acute pressure when performing a cognitive task, with some individuals performing better and some performing worse under pressure. Cortisol interacted with testosterone – high cortisol was negatively correlated with performance under pressure, but high testosterone ameliorated this adverse effect. This work provides evidence that high pressure affects cognitive performance in non- humans and that physiological markers like hormones are important to understanding why and how some individuals “choke”.

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Available for download on Monday, November 29, 2021