Dyadic emotional and cognitive shifts in moral decision-making: EEG and autonomic similarity

This study examined how interpersonal neural and autonomic similarity varies when dyads shift their decision-making (DM) orientation (between cognitive and emotional orientations) while evaluating moral dilemmas with a first- and third-person perspective. Thirteen dyads participated in two interactive conditions in which they jointly negotiated moral decisions (first vs third perspective), while their electrophysiological (EEG) and autonomic activity were continuously recorded. Before each interaction, participants' DM orientations were assessed, and dyads' orientation shift was classified according to whether one or both members changed orientation between the dilemmas (single-shift vs. dual-shift dyads). Interpersonal dissimilarity was quantified through Euclidean Distance (EuDist) across EEG frequency bands and Skin Conductance Level (SCL), Heart Rate (HR), HR Variability (HRV). Delta and gamma bands showed greater inter-brain dissimilarity in frontal than temporo-central and parieto-occipital regions, indicating region-specific recruitment for moral negotiation. Regarding orientation shift, dual-shift dyads displayed significantly higher gamma-band similarity compared to single-shift dyads, regardless of moral perspective. About perspective, autonomic results revealed greater inter-individual dissimilarity during first- than third-person perspective across SCL, HR, and HRV. Current findings suggest that DM orientation shift impacts neural coherence in dyads negotiating moral dilemmas (especially gamma band), while moral dilemmas perspective influences individual autonomic engagement in dyads.