Frontal Delta Dissimilarity During Moral Persuasion: Insight from an EEG Hyperscanning Study

Background/Objectives: Persuasive communication in moral decision-making contexts involves complex emotional and cognitive processes. This study aimed to investigate electrophysiological (EEG) dissimilarity between individuals during a persuasive interaction on a moral dilemma. Methods: Participants were paired into 14 dyads in which a member assumed the role of Persuasive Agent (PA) and the other of Persuasion Target (PT), discussing a moral decision-making scenario while their neural activity was recorded through an EEG hyperscanning paradigm. Dyads were later categorized based on perceived viewpoint change (high, mixed, low), and dissimilarity within dyads in EEG bands was analyzed across frontal, temporo-central, and parieto-occipital regions in left and right hemispheres. Results: Results showed a significant increase in frontal delta-band dissimilarity in mixed dyads, compared to temporo-central and parieto-occipital areas. The greater frontal delta dissimilarity in mixed dyads likely reflects divergent emotional and motivational engagement during persuasion. Specifically, individuals who changed their viewpoint may have exhibited stronger emotional resonance and attentional engagement compared to their partner. Conclusions: The study advances understanding of the neural mechanisms underlying persuasion in morally charged contexts and offers new insights into dyadic brain dynamics during complex social exchanges.