Extended Data Fig. 5: Illustration of Group-averaged Neural Activity and rDLPFC-rTPJ Connectivity Analyses.

a, Group-averaged Neural Activity. We first assessed the neural responses of a single brain (i.e., individual neural activity) by performing pre-processing on the fNIRS denoised Oxy-Hb data, including discrete cosine transforms with cut-off period of 128 s and pre-coloring based on hemodynamic response function (HRF). The preprocessed Oxy-Hb time series of each channel were segmented into 3 conditions, i.e., the decision-making phase (illustrated in the figure), the waiting screen, and the outcome screen. The pre-processed Oxy-Hb during decision-making (outcome) phase was z-score transformed using the mean value and standard deviation of the waiting period (as baseline) and indicated decision-making (outcome) related activity⁷⁴. For each intergroup contest, we averaged across 3 participants sharing the same role to indicate the round-level neural responses of each 3-person group. b, Group-averaged rDLPFC-rTPJ connectivity. Similar to previous studies³⁷, we performed coherence analysis between each of the 7 channels in the rDLPFC with each of the 7 channels in the rTPJ (i.e., 49 channel pairs) for each participant. The calculation of functional connectivity between channel 8 in the rDLPFC and channel 9 in the rTPJ was illustrated in the figure. We then averaged the coherence values of the 3 participants within the same group to indicate the group-averaged functional connectivity (GFC) of rDLPFC–rTPJ.