Perceived differences between chimpanzee (Pan troglodytes) and human (Homo sapiens) facial expressions are related to emotional interpretation

Citation

Waller BM, Bard KA, Vick S & Smith Pasqualini MC (2007) Perceived differences between chimpanzee (Pan troglodytes) and human (Homo sapiens) facial expressions are related to emotional interpretation. Journal of Comparative Psychology, 121 (4), pp. 398-404. https://doi.org/10.1037/0735-7036.121.4.398

Abstract
Human face perception is a finely tuned, specialized process. When comparing faces between species, therefore, it is essential to consider how people make these observational judgments. Comparing facial expressions may be particularly problematic, given that people tend to consider them categorically as emotional signals, which may affect how accurately specific details are processed. The bared-teeth display (BT), observed in most primates, has been proposed as a homologue of the human smile (J. A. R. A. M. van Hooff, 1972). In this study, judgments of similarity between BT displays of chimpanzees (Pan troglodytes) and human smiles varied in relation to perceived emotional valence. When a chimpanzee BT was interpreted as fearful, observers tended to underestimate the magnitude of the relationship between certain features (the extent of lip corner raise) and human smiles. These judgments may reflect the combined effects of categorical emotional perception, configural face processing, and perceptual organization in mental imagery and may demonstrate the advantages of using standardized observational methods in comparative facial expression research.

Keywords
advantage; Affect; chimpanzee; Chimpanzees; difference; expression; EXTENT; Face; FACE perception; Faces; FACIAL expression; Facial Expressions; Feature; features; HOMO-SAPIENS; Imagery; Judgment; Judgments; mental; method; methods; NOV; ORGANIZATION; Pan troglodytes; PAN-TROGLODYTES; PEOPLE; Perception; primate; Primates; relationship; Research; SIGNALS; similarity; Smiles; TROGLODYTES

Journal
Journal of Comparative Psychology: Volume 121, Issue 4