Moral Decision-Making Style, Moral Persuasion, and Interpersonal Neurophysiological Synchronization: Insights from an EEG-BIO Hyperscanning Study

Purpose: Moral decision-making often involves interpersonal interactions in which individuals seek to influence others’ moral judgments. The present hyperscanning study aimed to examine whether the alignment of moral decision-making style (emotional vs. cognitive) between two individuals modulates neural and autonomic synchronization during a moral persuasion task. Methods: Fourteen pairs of individuals were categorized as either homologous (same style) or heterologous (different styles) based on their responses to a real-life moral dilemma. During the task, one individual (Pder) attempted to persuade the other (Pdee) of the superiority of their own moral justification, while EEG activity across five frequency band (delta, theta, alpha, gamma and beta) and autonomic signals (SCL, HR, HRV) were simultaneously recorded. Neural and physiological synchrony was analyzed using a dissimilarity index based on Euclidean distance. Results: EEG results revealed no significant differences between homologous and heterologous pairs, although dissimilarity in the delta band was significantly higher in frontal regions than in temporo-central and parieto-occipital areas. In contrast, autonomic results revealed greater SCL dissimilarity in heterologous pairs, indicating reduced emotional synchrony when moral styles diverge. Conclusion: These findings suggest that, while cortical synchrony may be more strongly shaped by the task demands and structure, shared moral orientations may promote greater peripheral affective alignment.