Training Interbrain Synchrony through Dyadic Neurofeedback Modulates Empathy-for-Pain

Dyadic neurofeedback offers a socially grounded approach for modulating neural processes that unfold between interacting individuals. While recent work demonstrates that dyadic neurofeedback can enhance inter-brain synchrony during interaction, whether its effects extend beyond the trained dyad remains unclear. Here, we examined whether dyadic neurofeedback targeting inter-brain synchrony in the inferior frontal gyrus (IFG) is associated with changes in empathy-for-pain toward unfamiliar social targets. One hundred and eighty-six participants, randomly assigned to dyads, completed three neurofeedback training sessions within one week. Feedback was contingent on real-time IFG inter-brain synchrony in the neurofeedback group or on prerecorded signals in the sham-feedback control group. Empathy-for-pain was assessed before and after training. IFG inter-brain synchrony increased significantly across sessions in the neurofeedback group but not in the control group. Empathy-for-pain ratings showed different trajectories across conditions in the primary raw-data analysis, decreasing significantly in the sham-feedback group while remaining relatively stable in the neurofeedback group. A secondary analysis adjusting for a previously observed task-specific test-retest decline showed a significant increase in the neurofeedback group. Individuals with lower baseline trait empathy showed larger training-related increases in IFG inter-brain synchrony. Network analyses suggested broader changes involving IFG-IPL connectivity. Structural equation modeling further identified significant associations among training-related intra-brain synchrony, inter-brain synchrony, and empathy-for-pain change, consistent with the proposed relationship among these processes. Together, the findings indicate that dyadic neurofeedback can modulate IFG inter-brain synchrony across repeated training and may influence the trajectory of empathy-for-pain responding beyond the immediate training partner.