Face processing in humans and new world monkeys: the influence of experiential and ecological factors

Abstract

This study tests whether the face-processing system of humans and a nonhuman primate species share characteristics that would allow for early and quick processing of socially salient stimuli: a sensitivity toward conspecific faces, a sensitivity toward highly practiced face stimuli, and an ability to generalize changes in the face that do not suggest a new identity, such as a face differently oriented. The look rates by adult tamarins and humans toward conspecific and other primate faces were examined to determine if these characteristics are shared. A visual paired comparison (VPC) task presented subjects with either a human face, chimpanzee face, tamarin face, or an object as a sample, and then a pair containing the previous stimulus and a novel stimulus was presented. The stimuli were either presented all in an upright orientation, or all in an inverted orientation. The novel stimulus in the pair was either an orientation change of the same face/object or a new example of the same type of face/object, and the stimuli were shown either in an upright orientation or in an inverted orientation. Preference to novelty scores revealed that humans attended most to novel individual human faces, and this effect decreased significantly if the stimuli were inverted. Tamarins showed preferential looking toward novel orientations of previously seen tamarin faces in the upright orientation, but not in an inverted orientation. Similarly, their preference to look longer at novel tamarin and human faces within the pair was reduced significantly with inverted stimuli. The results confirmed prior findings in humans that novel human faces generate more attention in the upright than in the inverted orientation. The monkeys also attended more to faces of conspecifics, but showed an inversion effect to orientation change in tamarin faces and to identity changes in tamarin and human faces. The results indicate configural processing restricted to particular kinds of primate faces by a New World monkey species, with configural processing influenced by life experience (human faces and tamarin faces) and specialized to process orientation changes specific to conspecific faces.

The evolution of face processing in primates

“…Human subjects with no chimpanzee expertise have recently been shown to use holistic processing (composite effect) for chimpanzee faces, compared with the faces of more phylogenetically distant species including gorillas [70]. However, there is little evidence beyond these data for any type of configural superiority for human or chimpanzee faces and the basic first-order configuration is similar in all primate faces [32,36,39].…”

“…In addition, similar to previous studies, the majority of the fixations were directed towards the eyes. These free viewing tasks are often used to demonstrate individual recognition, as defined above; however, because the test pair contained one previously viewed photograph and one novel photograph, subjects could simply have responded with increased attention to the novel photograph, not selective attention to the novel individual (see also [36]). …”

Geometric distortions affect face recognition in chimpanzees (Pan troglodytes) and monkeys (Macaca mulatta)

“…Face recognition in nonhuman primates is also characterized by the inversion effect, providing evidence of holistic processing for upright faces ( cotton-top tamarins , Neiworth, Hassett and Sylvester 2007: chimpanzees , Parr et al 1998; Parr and Heintz 2008; Tomonaga 2007; Tomonaga et al 1993: Japanese monkeys , Tomonaga 1994: rhesus monkeys , Dahl et al 2007; Gothard et al 2009; Parr et al 2008; Vermeire and Hamilton 1998). An outstanding question, however, is whether all primates use the same second-order information to recognize faces.…”

A Capuchin Monkey (Cebus apella) Uses Video to Find Food

“…cats, snakes), but no such reactions to the videos of non-predator mammals. Using a preference to novelty paradigm, Neworth et al [2004] found categorical representation of pictures by cotton-top tamarins at a level similar to human infants, and Neworth et al [2007] report that tamarins show an experientially driven configural picture processing strategy toward the faces of species with which they have vast experience (tamarins and humans) and a conspecific configural processing toward subtle changes in tamarin faces. Anderson et al [2009] tested video self-recognition in tufted capuchins.…”