Face and eye scanning in gorillas (Gorilla gorilla), orangutans (Pongo pygmaeus), and humans (Homo sapiens): Unique eye-viewing patterns in humans among hominids

Publication Type:
 Journal Article
Year of Publication:
 2012
Authors:
 Fumihiro Kano, Josep Call, Masaki Tomonaga
Publication/Journal:
 Jounal of Comparative Physchology
Keywords:
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Abstract:

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 chimpanzees (Pan troglodytes) with humans (Homo sapiens), this study used the eye-tracking method to directly compare the patterns of face and eye scanning by humans, gorillas (Gorilla gorilla), and orangutans (Pongo pygmaeus). Human and ape participants freely viewed pictures of whole bodies and full faces of conspecifics and allospecifics under the same experimental conditions. All species were strikingly similar in that they viewed predominantly faces and eyes. No particular differencewas identified between gorillas and orangutans, and they also did not differ from the chimpanzees tested in previous studies. However, humans were somewhat different fromapes, especiallywith respect toprolonged eye viewing.We also examinedhowspecies-specific facial morphologies, such as themale flange of orangutans and the black–white contrast of human eyes, affected viewing patterns.Whereas themale flange of orangutans affected viewing patterns, the color contrast of human eyes did not. Humans showed prolonged eye viewing independently of the eye color of presented faces, indicating that this
pattern is internally driven rather than stimulus dependent. Overall, the results show general similarities among the species and also identify unique eye-viewing patterns in humans.

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