Affiliative bonding between teachers and students through interpersonal synchronization in brain activity

Human beings organize socially. Theories have posited that interpersonal neural synchronization might underlie the creation of affiliative bonds. Previous studies tested this hypothesis mainly during a social interaction, making it difficult to determine whether the identified synchronization is associated with affiliative bonding or with social interaction. This study addressed this issue by focusing on the teacher-student relationship in the resting state both before and after a teaching period. Brain activity was simultaneously measured in both individuals using functional near-infrared spectroscopy (fNIRS). The results showed a significant increase in brain synchronization at the right sensorimotor cortex between the teacher and student in the resting state after, but not before, the teaching period. Moreover, the synchronization increased only after a turn-taking mode of teaching but not after a lecturing or video mode of teaching. A chain mediation analysis showed that brain synchronization during teaching partially mediated the relationship between the brain synchronization increase in the resting state and strength of the affiliative bond. Finally, both role assignment and social interaction were found to be required for affiliative bonding. Together, these results support the hypothesis that interpersonal synchronization in brain activity underlies affiliative bonding and that social interaction mechanically mediates the bonding process.