Do monkeys compare themselves to others?

Abstract

Social comparisons are a fundamental characteristic of human behaviour, yet relatively little is known about their evolutionary foundations. Adapting the co-acting paradigm from human research (Seta in J Pers Soc Psychol 42:281–291, 1982. doi:10.1037//0022-3514.42.2.281), we examined how the performance of a partner influenced subjects’ performance in long-tailed macaques (Macaca fascicularis). Using parallel testing in touch screen setups in which subjects had to discriminate familiar and novel photographs of men and women, we investigated whether accuracy and reaction time were influenced by partner performance and relationship quality (affiliate vs. non-affiliate). Auditory feedback about the alleged performance of the co-actor was provided via playback; partner performance was either moderately or extremely better or worse than subject performance. We predicted that subjects would assimilate to moderately different comparison standards as well as to affiliates and contrast away from extreme standards and non-affiliates. Subjects instantly generalized to novel pictures. While accuracy was not affected by any of the factors, long reaction times occurred more frequently when subjects were tested with a non-affiliate who was performing worse, compared to one who was doing better than them (80 % quantile worse: 5.1, better: 4.3 s). For affiliate co-actors, there was no marked effect (worse: 4.4, better: 4.6 s). In a control condition with no auditory feedback, subjects performed somewhat better in the presence of affiliates (M = 77.8 % correct) compared to non-affiliates (M = 71.1 %), while reaction time was not affected. Apparently, subjects were sensitive to partner identity and performance, yet variation in motivation rather than assimilation and contrast effects may account for the observed effects.Electronic supplementary materialThe online version of this article (doi:10.1007/s10071-015-0943-4) contains supplementary material, which is available to authorized users.

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

“…At first sight, our results seem to contradict two previous studies reporting social comparisons in non-human primates [11,12] and previous findings on social facilitation effects in macaques (for an overview, see [18]). However, such differences might rely on methodological details, including task type, trial duration, partner orientation and distance, choice of comparison standards and response measure.…”

“…Social comparisons with group members might also be useful to decide how to choose good or fair interaction partners in future encounters (see [10]). This said, the systematic study of human-like social comparison effects is a relatively new topic in animal cognition research [11,12].…”

“…a performance that was within the capability of the participant, participants' performance increased compared with when working alone. Previous findings from a study that applied the co-action paradigm to long-tailed macaques (Macaca fascicularis) indicated that a certain level of competition might be necessary to draw subjects' attention to relevant aspects of the partner's behaviour and that simply working in parallel on two touchscreens is not sufficiently relevant for catching the monkeys' attention [12,14].…”

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

“…At first sight, our results seem to contradict two previous studies reporting social comparisons in nonhuman primates (11,12) and previous findings on social facilitation effects in macaques (for an overview, see (17). However, such differences might rely on methodological details, including task type, trial duration, partner orientation and distance, choice of comparison standards, and response measure.…”

Are monkeys intuitive Aristotelians? Associations between target size and vertical target position in long-tailed macaques

“…One female stopped participating due to giving birth and her data were only used for the analysis of Training Stage 1. Some subjects had participated in previous touchscreen tasks unrelated to the present study [ 37 ]. Water was always available ad libitum, and subjects were not food deprived for testing.…”