Facial and Vocal Individual Recognition in the Common Chimpanzee

Nonhuman primates posses a highly developed capacity for face recognition, which resembles the human capacity both cognitively and neurologically. Face recognition is typically tested by having subjects compare facial images, whereas there has been virtually no attention to how they connect these images to reality. Can nonhuman primates recognize familiar individuals in photographs? Such facial identification was examined in brown or tufted capuchin monkeys (Cebus apella), a New World primate, by letting subjects categorize facial images of conspecifics as either belonging to the in-group or out-group. After training on an oddity task with four images on a touch screen, subjects correctly identified one in-group member as odd among three out-group members, and vice versa. They generalized this knowledge to both new images of the same individuals and images of juveniles never presented before, thus suggesting facial identification based on real-life experience with the depicted individuals. This ability was unexplained by potential color cues because the same results were obtained with grayscale images. These tests demonstrate that capuchin monkeys, like humans, recognize whom they see in a picture.face recognition ͉ individual discrimination ͉ oddity ͉ primate ͉ visual discrimination

Section: Discussionsupporting

confidence: 52%

mentioning

confidence: 61%

Monkeys recognize the faces of group mates in photographs

Pokorny

Waal

2009

“…Nonhuman primates can process audiovisual information cross-modally to match indexical cues (20) and number of vocalizers (21), to match and tally quantity across senses (22) and associate the sound of different call types with images of conspecifics and heterospecifics producing these calls (23)(24)(25). Research aimed specifically at investigating the categorization of individuals has shown that hamsters (Mesocricetus auratus) are capable of matching multiple scent cues to the same individual (26) and that certain highly enculturated chimps (Pan troglodytes) can, through intensive training, learn to associate calls from known individuals with images of those individuals (27)(28)(29). Some species have also been shown to spontaneously integrate auditory and visual identity cues from their one highly familiar human caretaker during interspecific, lab-based trials (30,31).…”

Section: Discussionmentioning

confidence: 99%

Cross-modal individual recognition in domestic horses ( Equus caballus )

Proops

McComb²,

Reby³

2009

213

199

Individual recognition is considered a complex process and, although it is believed to be widespread across animal taxa, the cognitive mechanisms underlying this ability are poorly understood. An essential feature of individual recognition in humans is that it is cross-modal, allowing the matching of current sensory cues to identity with stored information about that specific individual from other modalities. Here, we use a cross-modal expectancy violation paradigm to provide a clear and systematic demonstration of cross-modal individual recognition in a nonhuman animal: the domestic horse. Subjects watched a herd member being led past them before the individual went of view, and a call from that or a different associate was played from a loudspeaker positioned close to the point of disappearance. When horses were shown one associate and then the call of a different associate was played, they responded more quickly and looked significantly longer in the direction of the call than when the call matched the herd member just seen, an indication that the incongruent combination violated their expectations. Thus, horses appear to possess a cross-modal representation of known individuals containing unique auditory and visual/olfactory information. Our paradigm could provide a powerful way to study individual recognition across a wide range of species.animal cognition ͉ vocal communication ͉ social behavior ͉ playback experiment ͉ expectancy violation H ow animals classify conspecifics provides insights into the social structure of a species and how they perceive their social world (1). Discrimination of kin from nonkin, and of individuals within both of these categories, is proposed to be of major significance in the evolution of social behavior (2, 3). Individual recognition can be seen as the most fine-grained categorization of conspecifics, and there is considerable interest in discovering the prevalence and complexity of this ability across species. While individual recognition is generally believed to be widespread (4), there is much debate as to what constitutes sound evidence of this ability (5). To demonstrate individual recognition, a paradigm must show that (i) discrimination operates at the level of the individual rather than at a broader level, and (ii) there is a matching of current sensory cues to identity with information stored in memory about that specific individual. Numerous studies to date have provided evidence for some form of social discrimination of auditory stimuli, but how this is achieved remains unclear. It is of considerable interest to establish whether any animal is capable of cross-modal integration of cues to identity, as this would suggest that in addition to the perception and recognition of stimuli in one domain, the brain could integrate such information into some form of higher-order representation that is independent of modality.A number of species have been shown to make very finegrained discriminations between different individuals (6-8). For example, in the habituation-dishabi...

“…The relative complexity of this process explains why individual recognition has long been thought to be a uniquely human capacity, which has been reported to develop ∼4 mo of age (35). However, it has recently been demonstrated in a few other species (16)(17)(18)(19) and might be more widespread in animals (36,37). Evidence for individual recognition by rhesus macaques raises the issue of the adaptive value of this very precise type of social recognition during interactions with conspecifics.…”

Section: Discussionmentioning

confidence: 99%

“…Only a few studies have applied this approach to investigate individual recognition in species other than humans and chimpanzees (16,17) and none of them focused on rhesus monkeys. Moreover, these studies explored individual recognition of peers (18,19), but did not examine whether this capacity extended to other species.…”

mentioning

confidence: 99%

Spontaneous voice–face identity matching by rhesus monkeys for familiar conspecifics and humans

Sliwa

Duhamel

Pascalis

et al. 2011

117

102

Recognition of a particular individual occurs when we reactivate links between current perceptual inputs and the previously formed representation of that person. This recognition can be achieved by identifying, separately or simultaneously, distinct elements such as the face, silhouette, or voice as belonging to one individual. In humans, those different cues are linked into one complex conceptual representation of individual identity. Here we tested whether rhesus macaques (Macaca mulatta) also have a cognitive representation of identity by evaluating whether they exhibit cross-modal individual recognition. Further, we assessed individual recognition of familiar conspecifics and familiar humans. In a free preferential looking time paradigm, we found that, for both species, monkeys spontaneously matched the faces of known individuals to their voices. This finding demonstrates that rhesus macaques possess a cross-modal cognitive representation of individuals that extends from conspecifics to humans, revealing the adaptive potential of identity recognition for individuals of socioecological relevance.cross-species | vocal communication | nonhuman primates | picture recognition I n humans, both faces and voices convey information about identity, providing some of the many cues we use to recognize individuals we know (1). The multifaceted nature of identity code suggests that a complex cognitive representation binds semantic information with information of different sensory modalities. In rhesus monkeys, however, it has typically been assessed only via single-modality information. For instance, rhesus monkeys can discriminate between calls of two conspecifics in a playback experiment using a spontaneous habituation-discrimination paradigm (2). They are also able to discriminate faces of two conspecifics in a match-to-sample task (3) and monkey faces or human faces in visual paired comparison tasks (4-6). These observations demonstrate that monkeys can discriminate idiosyncratic characteristics ("individual A is different from B") for their own or other species. However, they do not provide evidence of individual recognition ("this is individual A, this is B"). In comparison with discrimination, individual recognition requires an additional associative level that allows retrieval of information belonging to a specific individual. In rhesus monkeys, coarse recognition processes such as of their own species, kin, gender, reproductive status, or hierarchy are well documented (2, 7-12). However, these rudimentary recognition abilities fail to account for some sophisticated behaviors that are observed in rhesus macaques' societies. In particular, rhesus macaques live in large groups and maintain elaborate social relations involving, e.g., nonkin alliances during aggressive interactions, fight interference, reciprocal support, friendly grooming, and reconciliation (13-15). Such an organization would benefit well from the finest-grain individual recognition based on a cognitive multimodal representation of identity.Individu...