title: Familiar and unfamiliar face recognition in crested macaques (Macaca nigra).
abstract: Many species use facial features to identify conspecifics, which is necessary to navigate a complex social environment. The fundamental mechanisms underlying face processing are starting to be well understood in a variety of primate species. However, most studies focus on a limited subset of species tested with unfamiliar faces. As well as limiting our understanding of how widely distributed across species these skills are, this also limits our understanding of how primates process faces of individuals they know, and whether social factors (e.g. dominance and social bonds) influence how readily they recognize others. In this study, socially housed crested macaques voluntarily participated in a series of computerized matching-to-sample tasks investigating their ability to discriminate (i) unfamiliar individuals and (ii) members of their own social group. The macaques performed above chance on all tasks. Familiar faces were not easier to discriminate than unfamiliar faces. However, the subjects were better at discriminating higher ranking familiar individuals, but not unfamiliar ones. This suggests that our subjects applied their knowledge of their dominance hierarchies to the pictorial representation of their group mates. Faces of high-ranking individuals garner more social attention, and therefore might be more deeply encoded than other individuals. Our results extend the study of face recognition to a novel species, and consequently provide valuable data for future comparative studies.
authors.affiliation: Centre for Comparative and Evolutionary Psychology, Department of Psychology , University of Portsmouth , Portsmouth, UK.
authors.forename: Jérôme
authors.initials: J
authors.lastname: Micheletta
authors.affiliation: Centre for Comparative and Evolutionary Psychology, Department of Psychology , University of Portsmouth , Portsmouth, UK.
authors.forename: Jamie
authors.identifier: 0000-0002-4480-6781
authors.initials: J
authors.lastname: Whitehouse
authors.affiliation: Center for Translational Social Neuroscience, Silvio O. Conte Center for Oxytocin and Social Cognition, Department of Psychiatry and Behavioral Sciences , Emory University , Atlanta, GA, USA ; Yerkes National Primate Research Center , Emory University , Atlanta, GA, USA.
authors.forename: Lisa A
authors.initials: LA
authors.lastname: Parr
authors.affiliation: Centre for Comparative and Evolutionary Psychology, Department of Psychology , University of Portsmouth , Portsmouth, UK.
authors.forename: Paul
authors.initials: P
authors.lastname: Marshman
authors.affiliation: Junior Research Group for Primate Sexual Selection , German Primate Center , Göttingen, Germany ; Courant Research Centre for the Evolution of Social Behaviour , Georg-August University , Göttingen, Germany.
authors.forename: Antje
authors.identifier: 0000-0003-2704-7493
authors.initials: A
authors.lastname: Engelhardt
authors.affiliation: Centre for Comparative and Evolutionary Psychology, Department of Psychology , University of Portsmouth , Portsmouth, UK.
authors.forename: Bridget M
authors.initials: BM
authors.lastname: Waller
keywords: crested macaques; dominance; familiarity; individual recognition; matching-to-sample; social bond