Finding Agreement: fMRI-hyperscanning reveals that dyads explore in mental state space to align opinions

Many prize synchrony as the ingredient that turns a conversation from a debate into a delightful duet. Yet, learning from other people’s diverging opinions can also foster understanding and agreement, satisfy curiosity, and spur imagination. Using fMRI hyperscanning and natural language processing we tested how two debaters navigate conflictual conversations to find agreement. Dyads (N=60) discussed pressing societal problems while being instructed to either persuade their partner or compromise with each other. Our analysis uncovered three key insights: First, individuals instructed to compromise rather than persuade tended to agree more at the end of the session. Second, hyperscanning and linguistic analyses revealed that encouraging compromise resulted in increased exploration during conversations; dyads given compromise instructions traversed more diverse mental states and topics. Third, heightened exploration was linked to greater eventual agreement. Notably, the effect of the compromise instruction on agreement was entirely mediated by the degree of exploration. Together, these results suggest that trying to find agreement may be spurred by exploration, something that happens when people are motivated to compromise but not persuade.