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.

Capuchins recognize familiar faces

“…Secondorder configuration refers to the relative arrangement of facial features and surfacebased cues such as pigmentation and shading that provide the information necessary to individually discriminate faces (Diamond & Carey, 1986). Considering the studies that have employed methodologies that require direct responses from subjects, several nonhuman primate species have demonstrated the ability to individually discriminate conspecific faces, including chimpanzees (Parr et al, 2000(Parr et al, , 2011, orang-utans (Hanazuka, Shimahara, Tokuda, & Midorikawa, 2013;Talbot, Mayo, Stoinski, & Brosnan, 2015;Vonk & Hamilton, 2014), rhesus macaques (Rosenfeld & van Hoesen, 1979;Parr et al, 2000; see also Bruce, 1982;Heywood, Cowey, & Rolls, 1992), crested macaques, Macaca nigra (Micheletta et al, 2015), and capuchin monkeys (Pokorny & de Waal, 2009a). Yet the mechanism by which these species make these discriminations remains unclear.…”

“…Recently, two species of great apes have also demonstrated the familiarity effect when matching the same individual across viewpoints: chimpanzees (Parr, Siebert, & Taubert, 2011) and orang-utans (Talbot et al, 2015). In contrast, no effect of familiarity was found in crested macaques (Micheletta et al, 2015). Thus, the ability to combine second-order information and real-life experience to individually discriminate faces may reflect one facet of face processing that is unique to humans and apes.…”

Attention toward emotions is modulated by familiarity with the expressor: A comparison between bonobos and humans.

“…Other research indeed suggests that the social characteristics of the observer in relation to the observed individual(s) may play a role in how emotions are processed. For instance, attention can be modulated by sex (Schino et al, 2020), the social bond (Kutsukake, 2006; Whitehouse et al, 2016), rank (Lewis et al, 2021; Micheletta et al, 2015; Schino & Sciarretta, 2016), and kinship (Schino & Sciarretta, 2016). The current study sample did not allow us to disentangle the potential effects of social characteristics on an attentional bias toward emotions, but doing so in a new study would be a useful next step.…”

Male long‐tailed macaques (Macaca fascicularis) understand the target of facial threat

“…We employed a new paradigm to investigate whether macaques understand the target of attention, using the well assessed facts that monkeys know the dominance hierarchy in their social group [long‐tailed macaques: Cheney and Seyfarth, ], that they can recognize group members from pictures [rhesus macaques, Macaca mulatta : Parr et al, ; Silwa et al, ; Barbary macaques, Macaca sylvanus : Schell et al, ; grey‐cheeked mangabeys, Lophocebus albigena : Bovet and Deputte, ; brown capuchin monkeys: Pokorny and De Waal, ], that they recognize facial expressions from pictures [crested macaques, Macaca nigra : Micheletta et al, ] and that agonistic facial expressions in long‐tailed macaques are typically unidirectional [van Hooff, ], providing information about the target of attention. In this new paradigm, monkeys were shown pictures of social scenes involving three of their group members that were either congruent or incongruent concerning their group's dominance hierarchy.…”