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”.