title: 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.
authors.affiliation: Social Cognition Center Cologne, University of Cologne, Richard-Strauss-Str. 2, 50931, Cologne, Germany.|Cognitive Ethology Laboratory, German Primate Center, Kellnerweg 4, 37077, Göttingen, Germany.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Schmitt
authors.affiliation: Department of Cognitive Biology, University of Vienna, Althanstrasse 14, 1090, Vienna, Austria.
authors.forename: Ira
authors.initials: I
authors.lastname: Federspiel
authors.affiliation: Cognitive Ethology Laboratory, German Primate Center, Kellnerweg 4, 37077, Göttingen, Germany.
authors.forename: Johanna
authors.initials: J
authors.lastname: Eckert
authors.affiliation: Cognitive Ethology Laboratory, German Primate Center, Kellnerweg 4, 37077, Göttingen, Germany.|Leibniz ScienceCampus Primate Cognition, Kellnerweg 4, 37077, Göttingen, Germany.
authors.forename: Stefanie
authors.initials: S
authors.lastname: Keupp
authors.affiliation: Cognitive Ethology Laboratory, German Primate Center, Kellnerweg 4, 37077, Göttingen, Germany.
authors.forename: Laura
authors.initials: L
authors.lastname: Tschernek
authors.affiliation: Cognitive Ethology Laboratory, German Primate Center, Kellnerweg 4, 37077, Göttingen, Germany.
authors.forename: Lauriane
authors.initials: L
authors.lastname: Faraut
authors.affiliation: Department of Forest and Conservation Sciences, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada.
authors.forename: Richard
authors.initials: R
authors.lastname: Schuster
authors.affiliation: Social Cognition Center Cologne, University of Cologne, Richard-Strauss-Str. 2, 50931, Cologne, Germany.
authors.forename: Corinna
authors.initials: C
authors.lastname: Michels
authors.affiliation: Leibniz ScienceCampus Primate Cognition, Kellnerweg 4, 37077, Göttingen, Germany.
authors.forename: Holger
authors.initials: H
authors.lastname: Sennhenn-Reulen
authors.affiliation: Department of Cognitive Biology, University of Vienna, Althanstrasse 14, 1090, Vienna, Austria.
authors.forename: Thomas
authors.initials: T
authors.lastname: Bugnyar
authors.affiliation: Social Cognition Center Cologne, University of Cologne, Richard-Strauss-Str. 2, 50931, Cologne, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Mussweiler
authors.affiliation: Cognitive Ethology Laboratory, German Primate Center, Kellnerweg 4, 37077, Göttingen, Germany. jfischer@dpz.eu.|Leibniz ScienceCampus Primate Cognition, Kellnerweg 4, 37077, Göttingen, Germany. jfischer@dpz.eu.
authors.forename: Julia
authors.initials: J
authors.lastname: Fischer
mesh_terms: D000818:Animals; D003071:Cognition; D003299:Cooperative Behavior; D004192:Discrimination, Psychological; D005260:Female; D008252:Macaca fascicularis / Q000523:psychology*; D008297:Male; D011930:Reaction Time; D012919:Social Behavior
keywords: Co-acting paradigm; Evolution; Inequity aversion; Meta-cognition; Monkeys; Non-human primates; Social comparison processes; Social relationships