Competition is crucial for social comparison processes in long-tailed macaques

Humans modulate their self-evaluations and behaviour as a function of conspecific presence and performance. In this study we tested for the presence of human-like social comparison effects in long-tailed macaques (Macaca fascicularis). The monkeys’ task was to extract food from an apparatus by pulling drawers within reach and we measured latency between drawer-pulls. Subjects either worked on the task with a partner who could access the apparatus from an adjacent cage or worked with a partner present who was denied apparatus access. Alternatively, they worked in the absence of a conspecific present but with food moving towards the partner’s side. We further manipulated partner performance and competitiveness of the setup. We found no indication that long-tailed macaques compare their performance to the performance of conspecifics. They were not affected by the mere presence of the partner but they paid close attention to the partner’s actions when they were consequential for food availability. If social comparison processes are present in long-tailed macaques, the present study suggests they may only manifest in situations involving direct competition and would thus be different from social comparisons in humans, which manifest also in the absence of direct competition, for example in evaluative contexts.