Extended Data Fig. 7: Within-group Neural Synchronization after Winning or Losing.

We compared the GNS after the group won or lost the last round. We conducted Bonding (in-group bonding vs. no-bonding control) × Outcome of last-round T-1 (win_(T-1) vs. lose_(T-1)) mixed-model ANOVAs on GNS of round T. For both attacker (a) and defender (b) groups, the main effect of Outcome was not significant (a, Attacker: channel 8: F_1,82 = 3.357, p = 0.071, η² = 0.039; channel 11: F_1,82 = 1.164, p = 0.284, η² = 0.014; channel 4: F_1,82 = 2.893, p = 0.093, η² = 0.034; channel 13: F_1,82 = 0.824, p = 0.367, η² = 0.010; b, Defender: channel 8: F_1,82 = 1.321, p = 0.254, η² = 0.016; channel 11: F_1,82 = 2.100, p = 0.151, η² = 0.025; channel 4: F_1,82 = 0.008, p = 0.930, η² = 9.39 × 10⁻⁵; channel 13: F_1,82 = 0.183, p = 0.670, η² = 0.002). The Outcome effect was not modulated by in-group bonding (a, Attacker: channel 8: F_1,82 = 0.019, p = 0.890, η² = 2.35 × 10⁻⁴; channel 11: F_1,82 = 1.122, p = 0.293, η² = 0.014; channel 4: F_1,82 = 0.244, p = 0.622, η² = 0.003; channel 13: F_1,82 = 0.888, p = 0.349, η² = 0.011; b, Defender: channel 8: F_1,82 = 0.189, p = 0.665, η² = 0.002; channel 11: F_1,82 = 1.988, p = 0.162, η² = 0.024; channel 4: F_1,82 = 0.124, p = 0.725, η² = 0.002; channel 13: F_1,82 = 3.39 × 10⁻⁴, p = 0.985, η² = 4.14 × 10⁻⁶). Data from two sessions were excluded as attackers in these two sessions did not win any of the 24 rounds. Outcome-by-Bonding mixed-model ANOVAs (n = 84, 42 three-person groups under no-bonding control and 42 three-person groups under in-group bonding) separately for attacker groups and defender groups. Data are plotted as boxplots for each condition in which horizontal lines indicate median values, boxes indicate 25/75% quartiles, and whiskers indicate the 2.5-97.5% percentile range. Data points outside the range are shown separately as circles. Solid lines start from the mean and reflect the intervals for the Mean ± S.E. n.s. not significant.