Group decision-making behavior in social dilemmas: Inter-brain synchrony and the predictive role of personality traits

There are currently many studies available on individual decision-making (hereafter IDM) behavior; however, there are fewer that investigate how inter-brain social influences are substantiated in group decision-making behavior (hereafter GDM). This study examines the neural substrate of GDM and how an individual's personality affects the inter-brain synchrony of GDM in an economic social interaction situation. We used a functional near-infrared spectroscopy (fNIRS) hyperscanning system to simultaneously measure pairs of participants' inter-brain synchrony in a GDM game. The fNIRS results showed significant differences in inter-brain synchrony between IDM and GDM. Furthermore, agreeableness as a personality trait seems to be a predictive factor of inter-brain synchrony in GDM, and GDM is also influenced by the combination effect of personality and situation context. This investigation of inter-brain synchrony during group decision-making behavior improves not only our understanding of the neural substrate of group decision-making behavior and the association between personality traits and the neural network underlying GDM, but more generally contributes knowledge to the growing field of social neuroscience and neuroeconomics. •We study group decision-making behavior (GDM) in naturalistic social contexts.•GDM evoked higher inter-brain synchrony in the right inferior frontal gyrus.•Agreeableness seems to be a predictive factor of inter-brain synchrony in GDM.•GDM is influenced by the combination effect of personality and situation context.