Effect of Familiarity and Viewpoint on Face Recognition in Chimpanzees

Abstract

Numerous studies have shown that familiarity strongly influences how well humans recognize faces. This is particularly true when faces are encountered across a change in viewpoint. In this situation, recognition may be accomplished by matching partial or incomplete information about a face to a stored representation of the known individual, whereas such representations are not available for unknown faces. Chimpanzees, our closest living relatives, share many of the same behavioral specializations for face processing as humans, but the influence of familiarity and viewpoint have never been compared in the same study. Here, we examined the ability of chimpanzees to match the faces of familiar and unfamiliar conspecifics in their frontal and 3/4 views using a computerized task. Results showed that, while chimpanzees were able to accurately match both familiar and unfamiliar faces in their frontal orientations, performance was significantly impaired only when unfamiliar faces were presented across a change in viewpoint. Therefore, like in humans, face processing in chimpanzees appears to be sensitive to individual familiarity. We propose that familiarization is a robust mechanism for strengthening the representation of faces and has been conserved in primates to achieve efficient individual recognition over a range of natural viewing conditions.

Face Discriminations by Orangutans (Pongo spp.) Vary as a Function of Familiarity

“…Likewise, chimpanzees tested on a face recognition task performed better when individuating highly familiar conspecifics across photographs displaying different viewpoints of the same individual compared to moderately familiar conspecifics (subjects had prior exposure to these individuals only as test or training stimuli), and worse when individuating unfamiliar conspecifics (Parr et al 2011). In contrast, one study found that a gorilla and four orangutans performed at similar levels when discriminating familiar conspecifics and unfamiliar heterospecifics across various ages (Vonk and Hamilton 2014).…”

“…Importantly, the individuals we tested came from established social groups at Zoo Atlanta, where they spend their entire day in the company of other orangutans, eliminating the possibility that any differences we might find would be due to different exposure of the individuals to other orangutans, as opposed to species differences. Because orangutans share many cognitive traits with chimpanzees (Herrmann et al 2007;Russon 1998;Shumaker et al 2001;Tomasello and Call 1994), which have demonstrated skills of individual discrimination (Parr et al 2000;Parr et al 2011), and a recent study indicated that orangutans discriminate full body images (Vonk and Hamilton 2014), it is reasonable to predict that orangutans will perform similarly well on a conspecific face discrimination task. However, as humans and chimpanzees are better able to discriminate familiar as opposed to unfamiliar conspecific faces across viewpoints (Hill and Bruce 1996;Parr et al 2011) and exposure may improve one's ability to identify individuals (Fujita 1990;Martin-Malivel and Okada 2007;Tanaka 2003), we expected orangutans to better discriminate familiar as opposed to unfamiliar faces.…”

Familiar and unfamiliar face recognition in crested macaques (Macaca nigra)

“…Capuchin monkeys tested in a similar task were even more successful with unfamiliar faces than familiar ones, possibly because of the novelty such stimuli provide [ 9 ]. So far, only chimpanzees displayed the same familiar face advantage as humans, possibly because of the fission–fusion nature of chimpanzees' social organization [ 62 ]. In Parr and co-workers' study, the subjects were not personally familiar with the individuals; rather, the same stimuli were used as in a number of prior studies and so the chimpanzees knew the faces but had never interacted with the individuals.…”

Peer Review #1 of "Neural representation of face familiarity in an awake chimpanzee (v0.1)"

“…Neuroimaging studies have further elucidated that facial familiarity modulates not only ventral visual areas, but also distributed networks, including affective and memory-related regions, including the amygdala and medial parietal areas (Gobbini & Haxby, 2007;Natu & O'Toole, 2011). Concerning chimpanzees, behavioral studies have revealed that familiarity with the target enhances identification of individuals (Parr, Siebert, & Taubert, 2011), but neural responses to PeerJ reviewing PDF | (v2013:10:871:1:0:NEW 16 Nov 2013)…”