Cognitive and emotional engagement in negotiation: insights from EEG and fNIRS Hyperscanning.

In negotiation, individuals collaborate to achieve a shared goal and reach a mutual agreement by understanding their partner's intentions and adapting to them. Unlike most social cognition studies that investigate brain activity in individuals separately, this study employed an innovative hyperscanning approach, which is able to explore the inter-brain synchronization during negotiation. 26 students, divided into 13 dyads, participated in a negotiation decision-making task, requiring convergence on a shared course of action. The interaction was segmented offline into three phases: opener (sharing of individual opinions), central (negotiation), and final phase (shared decision). Electrophysiological (EEG delta, theta, alpha, beta and gamma bands) and hemodynamic (oxygenated-OHb and deoxygenated-HHb hemoglobin) data were collected. Higher HHb levels were observed during the central phase compared to the final phase, suggesting a relative decrease in frontal activation, potentially due to a shift in cognitive processing toward temporoparietal regions, as indicated by EEG findings. Increased delta, theta, and alpha activity was reported in the frontal area, suggesting the engagement of emotional and motivational systems as well as cortical resources for information processing. Finally, beta and gamma bands showed higher activity in the temporo-central and parieto-occipital areas, indicating the activation of perspective-taking. This study highlights how hyperscanning reveals the neural mechanisms of negotiation, where emotional, cognitive, and perspective-taking processes converge.