Dyad sex composition effect on inter-brain synchronization in face-to-face cooperation

Brain Imaging Behav. 2021 Jun;15(3):1667-1675. doi: 10.1007/s11682-020-00361-z.


Human cooperation behavior based on reciprocal altruism has been a hallmark of ancient and modern societies. Prior studies have indicated that inter-brain synchronization (IBS) between partners could exist during cooperation. However, how the sex composition of dyads influences the neural synchronization is still poorly understood. Here, we adopted functional near-infrared spectroscopy (fNIRS) based hyperscanning and a task of building blocks to investigate the sex composition effect on IBS in face-to-face cooperation in a natural situation, by evaluating brain-to-brain interactions of forty-five same-sex and mixed-sex dyads. Results showed significantly stronger inter-brain synchronization in Brodmann area 10 (BA10) in cooperation. In addition, variance analysis indicated that only male-male dyads showed increased inter-brain synchronization in left inferior frontal region (i.e., BA10) specific to cooperation. More importantly, the inter-brain synchronization in male-male dyads was significantly greater than that in male-female and female-female dyads. These findings provide support for the impact of sex composition on social cooperation in a naturalistic interactive setting and extend our knowledge on the neural basis of face-to-face cooperation.

Keywords: Inter-brain synchronization; Sex composition effect; Social cooperation; fNIRS hyperscanning.

MeSH terms

  • Brain
  • Brain Mapping*
  • Cooperative Behavior
  • Female
  • Humans
  • Interpersonal Relations*
  • Magnetic Resonance Imaging
  • Male