Social inhibition and behavioural flexibility when the context changes: a comparison across six primate species

Abstract

The ability to inhibit previously employed strategies and flexibly adjust behavioural responses to external conditions may be critical for individual survival. However, it is unclear which factors predict their distribution across species. Here, we investigated social inhibition and behavioural flexibility in six primate species (chimpanzees, bonobos, orangutans, gorillas, capuchin monkeys and spider monkeys) differing in terms of phylogenetic relatedness, foraging ecology and social organization. Depending on the social context, individuals could maximize their food intake by inhibiting the selection of a larger food reward in one condition (i.e. inhibition), but not in others, which required them to flexibly switching strategies across conditions (i.e. behavioural flexibility). Overall, our study revealed inter-specific differences in social inhibition and behavioural flexibility, which partially reflected differences in fission-fusion dynamics. In particular, orangutans and chimpanzees showed the highest level of inhibitory skills, while gorillas and capuchin monkeys showed the lowest one. In terms of behavioural flexibility, orangutans and spider monkeys were the best performers, while bonobos and capuchin monkeys were the worst ones. These results contribute to our understanding that inhibition and behavioural flexibility may be linked in more complex ways than usually thought, although both abilities play a crucial role in efficient problem solving.

Figure 1

(A) Pictorial representation of the apparatus. (B) Setup for the trial types in the Experimental and Control condition. Due to differences in the species’ housing, for capuchin monkeys in the Control trials the partner was in a room adjacent to the back (rather than the side) of the other testing rooms.

Figure 2

Mean (±SE) probability of making the correct choice (SR) in all ExpSR sessions for each species. Results are averaged over the levels of subject’s sex and age, and partner’s position (Model 1). The dotted line illustrates the probability of making a correct choice by chance.

Figure 3

Mean (±SE) probability of making the correct choice (LR) in all ContSR sessions for each species. Results are averaged over the levels of subject’s sex and age, and partner’s position (Model 3). The dotted line illustrates the probability of making a correct choice by chance. Mean probabilities in ExpLR sessions are not reported, as there were no inter-specific differences in these sessions.