Distinct fNIRS Inter-Brain Coupling Patterns for Cooperation versus Competition in a Tennis Game

Cooperation and competition represent two fundamental modes of social interaction, yet their underlying neural mechanisms remain incompletely understood. Functional near-infrared spectroscopy hyperscanning, enabling simultaneous measurement of hemodynamic activity across individuals, offers unique insights into the neural substrates underlying naturalistic interactions. Using this technique, we investigated cross-channel inter-brain coupling (IBC) between interacting individuals during cooperative and competitive play in a motion-sensing tennis game. Compared to resting-state and solo gameplay with observation, both conditions elicit significantly enhanced not only IBC between the dyads' sensorimotor regions, but also cross-regional coupling between one participant's sensorimotor cortex and the other's dorsolateral prefrontal cortex (DLPFC) as well as temporoparietal junction, suggesting the contribution of high-order cognition networks to the observed IBC. Notably, competitive interactions produce stronger cross-regional IBC between DLPFC and sensorimotor regions than cooperative ones, implying an intensified demand for cognitive control during competition. Conversely, cooperation enhances neural coupling between team-mates within their prefrontal cortices, which could reflect shared goal representations. Behavioural cooperation performance is negatively correlated with the DLPFC-sensorimotor IBC. These spatially distinct patterns of condition-dependent neural coupling advance our understanding of the neural underpinnings of naturalistic social interactions.