Behaviour of tufted capuchin monkeys in a snowdrift game: is there a role for self-control?

Social dilemmas play an important role in the study of cooperative behaviours. In this experiment we tested the strategies adopted by tufted capuchin monkeys, Sapajus spp., when faced with a cooperative situation involving a conflict of interest, simulating a Snowdrift game. We tested 12 capuchin monkeys (six dyads) in two experimental conditions: Snowdrift (cooperation) and Competition. Monkeys had the opportunity to pull a string to move a rotating bar and obtain a reward while delivering a different reward to their partner. Pulling in the Snowdrift condition delivered a smaller reward to the individual pulling the string and a larger reward to the partner, while the opposite happened in the Competition condition. If neither monkey pulled within 30 s, neither received a reward. Monkeys were also individually tested in a battery of self-control tasks. Capuchin monkeys successfully coordinated (i.e. obtained a reward) in 100% of trials and flexibly adapted their behaviour to the different experimental conditions, by pulling earlier in the Competition and later in the Snowdrift condition. Dominance rank and self-control had no effect on the latencies to pull in either experimental condition. No evidence of any alternation strategy was observed. Our results suggest that capuchin monkeys can solve a conflict of interest without engaging in complex calculations. (c) 2022 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.