Capuchin monkeys: Cognitive performance was impaired by negative experiences; contrary to predictions, positive experiences did not have a facilitative effect on cognitive performance

Webster, M. F., & Brosnan, S. F. (2021). The effects of positive and negative experiences on subsequent behavior and cognitive performance in capuchin monkeys (Sapajus [Cebus] apella). Journal of Comparative Psychology, Aug 2021. https://doi.org/10.1037/com0000277

Abstract: Our understanding of animals’ affective processing is notably limited compared to the wealth of research on humans, largely due to difficulties in measurement. Moreover, despite a recent increase in the understanding of the interaction between affect and cognition in animals, most research has focused on negative affect, with the result that we continue to know little about the effects of positive affect. In this study, we tested 15 adult capuchin monkeys (Sapajus [Cebus] apella) using a novel methodology that took advantage of capuchins’ species-typical behavior to engineer both a positive and negative experience, using the same apparatus to minimize extraneous impacts. Following a positive or negative experience (that presumably induced positive and negative affect, respectively), or a control with no manipulation, we assessed subjects’ performance on a cognitive task, a computerized delayed match-to-sample. As predicted, behavior following the negative condition suggested a negative affective state, with increased rates of scratching (commonly used as an indicator of stress in nonhuman primates) compared to both the positive and control conditions. Cognitive performance was also impaired in the negative condition compared to the other two. Contrary to predictions, however, the positive condition did not have a facilitative effect on cognitive performance, but behavioral results indicate that we may not have induced a truly positive affective state. Although we add to evidence that a negative experience can influence subsequent behavior and cognitive performance in nonhuman primates, our work highlights our lack of knowledge about the impact of positive affect, if any, on behavior and cognition.