Verbally mediated cooperation is consistently associated with inter-brain synchrony in frontal and temporoparietal areas: A mini-review and meta-analysis

Cooperation, often supported through verbal communication, is vital to the survival of our species. Recent research has suggested that cooperative behavior is associated with synchronized neural activity between dyads in the frontal and temporo-parietal regions, consistent with findings from single-brain laboratory studies. However, these studies use a variety of cooperation tasks, raising the question whether the reported results can be reliably linked to truly dynamic, verbally supported cooperation. To establish which of these regions, if any, consistently track naturalistic cooperative behavior, we conducted a brief review and meta-analysis of published functional near-infrared spectroscopy (fNIRS) hyperscanning studies examining the occurrence of inter-brain synchrony during cooperative interactions as participants engaged in verbal communication. Nine articles (n=737 participants) met selection criteria and provided evidence of inter-brain synchrony during spoken communication while cooperating, with significantly large overall effect sizes for the full set of experimental conditions in both frontal and temporoparietal areas, suggesting that inter-brain neural synchronization in these regions underlies cooperative behavior in humans. Together, our findings underscore the importance of meta-analyses as a tool to help discern patterns across studies, in this case shedding light on the neural basis of semi-naturalistic cooperative behavior.