Interbrain Coupling during Interpersonal Conflict: an fNIRS hyperscanning study

Interpersonal conflict constitutes a ubiquitous social interaction phenomenon, yet prior research has predominantly emphasized conflict-eliciting contexts while leaving the construct underspecified and minimally investigated through cognitive-neuroscientific frameworks. Guided by the disagreement–interference–negative affect triad, we re-engineered the classic Greedy Snake game to establish two real-time interactive paradigms (Conflict vs. Non-Conflict), thereby operationalizing conflict. Using functional near-infrared spectroscopy hyperscanning (fNIRS-hyperscanning), we recorded hemodynamic responses from 52 university student dyads (N = 104) during task execution. After excluding data that did not meet quality standards, 44 dyads were included for neural analysis. Behaviorally, the Conflict paradigm significantly amplified subjective perceptions of goal incongruence, mutual interference and negative affect, validating experimental manipulation. Neurally, compared with the Non-Conflict group, the Conflict group elicited stronger oxygenated hemoglobin (HbO) responses in the left inferior frontal gyrus (lIFG), dorsolateral prefrontal cortex (dlPFC), and right temporoparietal junction (rTPJ), with higher inter-brain synchrony (IBS) in these regions. These results delineate three integrated neural modules: (i) a sensory-language-attentional network (lIFG/dlPFC) supporting conflict monitoring; (ii) a mentalizing-reward network (rTPJ) mediating social intention inference; and (iii) a mirror-motor network governing antagonistic behavioral output, collectively providing novel evidence for multi-brain coordination mechanisms during interpersonal conflict within social neuroscience frameworks.