Interpersonal brain synchrony (IBS) during cooperation has not been systematically investigated. To address this research gap, this study assessed neural synchrony during a cooperative jigsaw puzzle solving task using functional near-infrared spectroscopy (fNIRS)-based hyperscanning. IBS was measured for successful and failed tasks in 31 dyads in which the partners were familiar or unknown to each other. No significant difference in IBS was observed between the different types of cooperative partnership; however, stronger IBS within regions of the pars triangularis Broca’s area, right frontopolar cortex, and right temporoparietal junction was observed during task success. These results highlight the effect of better task performance on cooperative IBS for the first time and further extend understanding of the neural basis of cooperation.

Children are at a critical stage of development for cultivating creativity and are highly sensitive to the influence of peers. This study investigated the impact of peer relationships on children's creativity during both cooperative and competitive interactions, using functional near-infrared spectroscopy (fNIRS)-based hyperscanning techniques. A total of 66 children, including 18 familiar dyads and 15 stranger dyads, were recruited to participate in the cooperative and competitive tangram puzzle tasks. The results showed that familiar dyads demonstrated higher originality and lower appropriateness in cooperative tasks compared to stranger dyads. fNIRS data revealed distinct task-specific neural coupling patterns in the inferior frontal gyrus (IFG) contingent upon peer relationship: familiar dyads exhibited enhanced inter-brain synchronization (IBS) during cooperative tasks, while stranger dyads demonstrated stronger neural alignment during competitive interactions. Additionally, positive feedback during cooperative interactions in familiar dyads was significantly correlated with increased IBS in the IFG. These findings underscore the advantages of familiar peer relationships in fostering cooperative creativity and the benefits of strange relationships in enhancing competitive performance. This study highlights the importance of considering relational and contextual factors in fostering children's creative potential.

Interpersonal conflict is a core yet complicated part of social interaction, involving complex mental and emotional processes. However, the neural mechanisms underlying interpersonal conflict are still not fully understood. This study employed functional near-infrared spectroscopy (fNIRS) hyperscanning to explore the brain activity related to interpersonal conflict through both passive video viewing and active role-playing paradigms. The results revealed an unexpected activation pattern – brain activity was highest at rest, lower during conflict, and lowest during neutral interactions (i.e., rest > conflict > neutral) in all ROIs except the rTPJ during active role-playing. This indicates a cortical deactivation effect when people engage in social processing. Additionally, the study found that inter-brain synchronization (IBS) between the two participants' brains decreased significantly during conflict compared to non-conflict conditions. These findings provide neurocognitive evidence for disrupted interpersonal alignment during conflict and highlight potential intervention targets—such as perspective-taking and interpersonal attunement—for enhancing social functioning in challenging interactions.