The Emotional Expressions and Emotion Perception in Nonhuman Primates

Abstract

The expression of emotions and their recognition in conspecifics are pivotal to social life. As Darwin postulated in his pioneering book The expression of the emotions in man and animals, many morphological features and functions of emotional expressions characterized in humans are homologous to those of other animals. Intriguingly, despite this early work, scientists have been skeptical about the feasibility of studying emotions in nonhumans and, therefore, the study of their emotional expressions has been limited. However, recent technological advances in neuroscience, genetics, and fine-scale behavioral analyses enable researchers to investigate human emotions in direct comparison with other animals. Throughout this chapter, the authors provide convincing evidence that nonhuman primates produce and recognize conspecific emotional expressions. Some of them, especially the bared-teeth display, are used in multiple contexts, suggesting cognitively sophisticated functions. The flexible use of emotional expressions seems to be tightly linked to species sociality, such as level of tolerance.

Priming using Human and Chimpanzee Expressions of Emotion Biases Attention toward Positive Emotions

“…Zooming in on potential explanations for this contradictory observation, the selected chimpanzee stimuli need to be closer examined. For the stimulus sub-set communicating negative affective states in chimpanzees, we chose one of the most frequently observed facial expressions across non-human primates: the bared-teeth display (Kim & Kret, 2022). Although in chimpanzees the expression predominantly occurs in agonistic interactions (Waller & Dunbar, 2005), it can signal different affective states in other species.…”

“…The copyright holder for this preprint this version posted October 20, 2023. ; https://doi.org/10.1101/2023.10.20.562671 doi: bioRxiv preprint chimpanzees, we chose one of the most frequently observed facial expressions across nonhuman primates: the bared-teeth display (Kim & Kret, 2022). Although in chimpanzees the expression predominantly occurs in agonistic interactions (Waller & Dunbar, 2005), it can signal different affective states in other species.…”