From the lab to the real world: emotions serving morality in dyadic negotiation.

Introduction: Confronting moral choices in contexts of limited resources requires individuals to integrate reasoning, emotions, and interpersonal dynamics. However, most research on moral decision-making relies on laboratory paradigms that limit ecological validity, restricting natural emotional expression. To address this limitation, this study examined how dyads converge on moral choices through real-time negotiation, focusing on the interplay between cognitive and emotional processing. Methods: Fifteen same-sex adult dyads participated in a moral evaluation task, deciding which of two patients to prioritise for treatment. During the negotiation, conducted in direct social interaction rather than in isolated lab-based evaluation, prefrontal cortex activity was simultaneously recorded in both participants using fNIRS hyperscanning, a paradigm suited to naturalistic interpersonal contexts. Results: Results revealed a significant increase in the dissimilarity in the deoxygenated haemoglobin (HHb) activity between channel 6 (F6-F4, right hemisphere) and channel 3 (F5-F3, left hemisphere);no significant effects were observed for oxygenated haemoglobin (O Discussion: These findings support the view that moral negotiation is a dynamic, affectively grounded process, shaped not only by cognitive deliberation but also by emotional information expressed through bodily and facial cues. By integrating hyperscanning with a naturalistic interpersonal setting, this study can contribute to bridging the gap between lab-based and real-world moral decision-making, offering insights into the neural underpinnings of shared evaluation.