Brain-to-brain synchronization of the expectation of cooperation behavior: A fNIRS hyperscanning study.

Expectation of cooperation (hereafter EOC) plays an important role in social dilemmas. In the present study, participant dyads performed an improved prisoner's dilemma game, with their prefrontal cortex and inferior frontal gyrus recorded via the functional near-infrared spectroscopy (fNIRS) hyperscanning technique. Inter brain results indicated significant inter-brain neural synchronization (INS) across participant pairs' inferior frontal gyrus (IFG) in high-powered incentives and defective expectation. Furthermore, the agreeableness proved to be a predictor of cooperative expectation in the inter brain frame. These results may revealed the inter-brain underlying substrate of EOC in social dilemmas and indicated the involvement of the mentalizing network and human mirror neuron system network in social dilemmas.