Personality and EEG correlates of reactive social behavior.

Reactive, as opposed to proactive, behavior during social interactions has been investigated in the study of aggression, but it is virtually unexplored in relation to other kinds of social behavior. Little is known about brain underpinning of these processes. In this study, we used a virtual interaction model to manipulate the emotional display of the interaction partner and to register actor's responses to these manipulations. EEG was recorded throughout the experiment. After the experiment, participants filled in the IPIP Big-Five Factor Markers. Multilevel mediation analysis using emotional stimulus category as the predictor, behavioral response as the outcome, and source-level oscillatory power as the mediator showed that event-related theta activity in the right temporo-parietal junction mediated the association between the predictor and the outcome. The strength of mediation was associated with agreeableness, suggesting that brain mechanism underlying reactive social behavior is more active in agreeable individuals.