EXPRESS: Facial attractiveness influenced cooperative behavior in the Stag Hunt game: evidence from neural electrophysiology

Facial attractiveness plays a significant role in interpersonal interactions, influencing various aspects of life. This study is the first to explore, from a neurological perspective, the impact of facial attractiveness on individual cooperative behavior in the context of the Stag Hunt game. 26 participants took part in a two-person Stag Hunt experimental task while their electroencephalogram (EEG) data was recorded. Participants had to decide whether to cooperate with or to defect from a virtual partner in the game, with photos of these partners (high or low attractiveness) shown before the decision. Analysis of the behavioral data indicates that faces with high attractiveness can promote individual cooperative behavior. EEG data analysis revealed that during the facial stimulus presentation phase, low attractiveness faces elicited more negative N2 amplitudes, smaller LPP amplitudes, and larger alpha oscillations compared to high attractiveness faces. During the outcome feedback phase, high attractiveness faces elicited smaller FRN amplitudes, larger P300 amplitudes, and stronger theta oscillations than low attractiveness faces, while loss feedback elicited more negative FRN amplitudes, smaller P300 amplitudes, and larger theta oscillations than gain feedback. These findings indicate that the processing of facial attractiveness occurs early and automatically, and it also influences individuals' evaluation of behavioral outcomes.