Brain Oscillations and Autonomic Synthonization via Comodulation in Collaborative Negotiation

Abstract

This study investigates the relationship between neural and physiological synthonization via comodulation (Synth) in dyadic exchanges centered on negotiation processes. In total, 13 dyads participated in a negotiation task with three phases: Initiation (IP), Negotiation Core (NCP), and Resolution (RP). Electroencephalographic (EEG) frequency bands (i.e., delta, theta, alpha) and autonomic responses (heart rate variability, HRV) were recorded. Synth was analyzed using Euclidean distance (EuDist) for EEG and autonomic indices. Significant Synth in delta, theta, and alpha bands in temporo-central and parieto-occipital regions was observed, indicating social cognitive alignment. HRV Synth was higher during the NCP than IP, suggesting better coordination. Based on this result, a cluster analysis was performed on HRV EuDist to identify distinct groups based on HRV, and eventually personality patterns, that revealed one cluster with higher Synth and reward sensitivity, and another with lower Synth and reward sensitivity. These findings show how neural and autonomic Synth enhances social cognition and emotional regulation.

Keywords: autonomic responses; decision-making; emotion regulation; inter-brain connectivity; negotiation; neural synthonization.

Figure 1

(a) Experimental procedure and (b) EEG electrode placement.

Figure 2

Cluster analysis results for HRV parameters. (a) A dendrogram representing the hierarchical clustering of the dataset. (b) Mean values of HRV parameters (IPHRV, NCPHRV, RPHRV) for the identified clusters. (c) A gap statistic plot indicating the optimal number of clusters. (d) A Principal Component Analysis (PCA) biplot showing the distribution of subjects in two-dimensional space (Dim1 and Dim2), with clusters represented by different symbols and convex hulls. Cluster 1 is depicted with circles, while Cluster 2 is represented with triangles.

Figure 3

The EuDist index across different regions of interest (ROIs). Each panel represents a different frequency band: (a) delta, (b) theta, (c) alpha. The y-axis indicates the EuDist index, while the x-axis represents three brain regions: frontal (ROI-F), temporo-central (ROI-TC), and parieto-occipital (ROI-PO). Error bars represent Standard Error (SE). Asterisks (*) indicate statistically significant differences between ROIs.

Figure 4

The EuDist index across task phases in the beta (a) and gamma (b) frequency bands, plotted separately for each region of interest (F = frontal; TC = temporo-central; PO = parieto-occipital). While descriptive trends suggest modest phase-related variations, no statistically significant effects or interactions were observed for either frequency band (all p > 0.05). Error bars represent standard deviations.

Figure 5

EuDist HRV index across phases (Initiation Phase IP, Negotiation Core Phase NCP, and Resolution Phase RP). Asterisks (*) indicate the statistically significant difference between the NCP and IP.

Figure 6

BAS Reward Responsiveness results. Asterisks (*) indicate the statistically significant difference between Cluster 1 and Cluster 2.