Intra- and inter-brain synchrony oscillations underlying social adjustment

Humans naturally synchronize their behaviour to other people. However, although it happens almost automatically, the adjustment of behaviour and the conformity to others is a complex phenomenon whose neural mechanisms are still yet to be completely understood. The goal of the present experiment was to study the oscillatory synchronization mechanisms underlying the automatic dyadic convergence in an EEG hyperscanning experiment. 36 people performed a purely cooperative decision-making task in dyads in which they had to guess the correct position of a point in a line. A reinforcement learning algorithm was used to model the expectancy of convergence among peers. Intra- and inter-connectivity among electrodes was assessed using inter-site phase clustering (ISPC) in three main frequency bands (theta, alpha, beta) using a two-level Bayesian Mixed Modelling approach. Results showed two different oscillatory synchronization dynamics related to attention and executive functions in alpha and reinforcement learning tracked by theta. In addition, inter-brain synchrony was mainly driven by beta oscillations. These results provide initial evidence about the role of inter- and intra- oscillatory synchrony in behavioural adaptation induced by social conformity.