Macaques can predict social outcomes from facial expressions

Area of Science:

• Primate behavior
• Social cognition
• Animal communication

Background:

• Facial expressions are crucial for social interactions, but their adaptive function in predicting future events is not well understood.
• Previous research has primarily viewed facial expressions as indicators of an individual's current emotional state.

Purpose of the Study:

• To investigate if macaques can utilize the facial expressions of others to anticipate the outcomes of social interactions.
• To determine the predictive value of specific facial displays, such as the bared-teeth expression, in social contexts.

Main Methods:

• Crested macaques (Macaca nigra) were presented with videos of two unknown individuals approaching each other on a touchscreen.
• Facial expressions of the individuals in the videos were manipulated in the final frame.
• Subjects had to choose between two potential social outcomes based on the displayed facial expressions.

Main Results:

• Macaques accurately predicted different social outcomes based on the facial expressions shown.
• The bared-teeth display was strongly associated with the prediction of friendly outcomes.
• Any facial expression, compared to a neutral face, led to a higher likelihood of choosing friendly outcomes, indicating a reduced probability of social conflict.

Conclusions:

• Facial expressions in macaques serve a predictive function in social interactions, enabling individuals to anticipate future events.
• These findings challenge traditional views by suggesting that facial expressions are part of complex social cognition, involving foresight rather than solely reflecting present emotions.
• The study highlights the adaptive role of facial communication in mediating social relationships and avoiding conflict.