Brain-to-brain coupling forecasts future joint action outcomes

In this study, we investigated whether brain-to-brain coupling patterns could predict performance in a time-estimation task that requires two players to cooperate. The participant pairs were tasked with synchronizing button presses after converging on a shared representation of "short," "medium," and "long" time intervals while utilizing feedback to adjust responses. We employed electroencephalogram (EEG)-hyperscanning and focused on post-feedback brain activity. We found that negative feedback led to increased frontal mid-line theta activity across individuals. Moreover, a correlation in post-feedback theta power between players forecasted failed joint action, while an anti-correlation forecasted success. These findings suggest that temporally coupled feedback-related brain activity between two individuals serves as an indicator of redundancy in adjustment of a common goal representation. Additionally, the anti-correlation of this activity reflects cognitive strategic mechanisms that ensure optimal joint action outcomes. Rather than a paired overcompensation, successful cooperation requires flexible strategic agility from both partners.