# Electrophysiological Hyperscanning of Negotiation During Group-Oriented Decision-Making
## 4 Discussion  
This study investigated the single-brain EEG correlates of group-oriented individuals during a decision-making process with an explicit negotiation goal, as well as the inter-brain neural activity of dyads converging on the decision. The findings contribute to the growing body of literature on social neuroscience by elucidating how negotiation processes in dyads shape individual and inter-brain neural dynamics. Specifically, negotiation was studied through a communicative ecologically valid scenario that involves synchrony and turn-taking. The modulation of different EEG frequency bands and inter-brain synchronization during negotiation allowed to explore the extent of shared cognitive and emotional states between interacting partners. Figure 3: The bar chart shows the Euclidean Distance between the power spectral density (PSD) values across the three ROIs (F = frontal, TC = temporo-central, PO = parieto-occipital). Bars represent \(\pm 1\) standard error and stars (*) mark statistically significant effects. The behavioral findings confirmed that participants demonstrated a clear preference for group-oriented decision-making over individualistic approaches. This behavioral predisposition is mirrored by the neurophysiological patterns observed during the negotiation task. The increase in frontal delta and theta power likely reflects the affective-motivational engagement and strategic regulation characteristic of cooperative social cognition, while the enhanced parieto-occipital beta and gamma activity suggests a reliance on integrative and monitoring processes necessary for converging toward a shared solution. Together, these findings support the notion that group-oriented decision-making is instantiated through a specific configuration of distributed cortical activity during negotiation. This aligns with prior research suggesting that individuals with a cooperative orientation tend to prioritize collective interests and shared perspectives in decision-making contexts [1]. Interestingly, participants reported that their partners influenced their decisions to a moderate extent, but their initial perceptions of group dynamics remained relatively stable. This suggests that, while negotiation fosters an exchange of ideas, individuals may integrate new perspectives without completely altering their initial viewpoints. Additionally, high ratings for cohesion and alliance, coupled with low scores for conflict and empathic failure, indicate that the negotiation process was largely cooperative and prosocial in nature. This interpersonal pattern may also highlight the observed inter-brain dissociation in delta power, which we interpret as reflecting individual regulatory engagement within a non-adversarial, co-constructed exchange. The EEG findings reveal distinct neural patterns associated with negotiation, providing insights into the cognitive and emotional mechanisms underlying group-oriented decision-making. Firstly, the single-brain analysis demonstrated increased delta and theta activity in the frontal region compared to the parieto-occipital region. This is consistent with previous studies linking frontal delta and theta oscillations to emotional engagement, motivation, and goal-directed control [20,29]. Moreover, former hyperscanning works demonstrated the key role of frontal areas in cooperation process [37] as well as the prefrontal cortex, implicated in joint action performance [39]. These findings suggest that negotiation involves heightened emotional and cognitive effort, particularly in this sample of individuals committed to group-oriented goals. Moreover, alpha activity was higher in the frontal region than in the temporo-central region during the negotiation task. The suppression of oscillations within the alpha frequency range is an index of cortical excitability [52] and enhances the efficiency of cognitive processing [53].