How chimpanzees look at pictures: a comparative eye-tracking study
Surprisingly little is known about the eye movements of chimpanzees, despite the potential contribution of such knowledge to comparative cognition studies. Here, we present the first examination of eye tracking in chimpanzees. We recorded the eye movements of chimpanzees as they viewed naturalistic pictures containing a full-body image of a chimpanzee, a human or another […]
Face scanning in chimpanzees and humans: continuity and discontinuity
How do chimpanzees, Pan troglodytes, the species with the closest evolutionary connection to humans, view faces? This study is the first to use the eye-tracking method to perform direct comparisons between humans and chimpanzees with regard to face scanning. Members of both species viewed the same sets of photographs representing conspecific and nonconspecific faces under […]
The use of nasal skin temperature measurements in studying emotion in macaque monkeys
Using an infrared thermographic system, we have demonstrated, as previously reported, that temperatures in the nasal region of macaque monkeys decrease during negative emotional states, such as when facing a threatening person. In this study, we explored the usefulness of measuring nasal skin temperatures in studies of monkey emotions as manifested by conspecific emotional behaviors […]
Visual kin recognition in nonhuman primates: (Pan troglodytes and Macaca mulatta): Inbreeding avoidance or male distinctiveness?
Faces provide important information about identity, age, and even kinship. A previous study in chimpanzees reported greater similarity between the faces of mothers and sons compared with mothers and daughters, or unrelated individuals. This was interpreted as an inbreeding avoidance mechanism where females, the dispersing gender, should avoid mating with any male that resembles their […]
Face and eye scanning in gorillas (Gorilla gorilla), orangutans (Pongo pygmaeus), and humans (Homo sapiens): Unique eye-viewing patterns in humans among hominids
Because the faces and eyes of primates convey a rich array of social information, the way in which primates view faces and eyes reflects species-specific strategies for facial communication. How are humans and closely related species such as great apes similar and different in their viewing patterns for faces and eyes? Following previous studies comparing […]
Face-based perception of emotions in dairy goats
Faces of conspecifics convey information about identity, but also gaze, and attentional or emotional state. As a cognitive process, face-based emotion recognition can be subject to judgement bias. In this study we investigated whether dairy goats (n = 32) would show different responses to 2-D images of faces of familiar conspecifics displaying positive or negative […]