How emotional disclosure enhances interpersonal closeness from a speaker-listener perspective: An fNIRS hyperscanning...

Conversation plays a vital role in daily social interactions, serving as a key channel for transmitting information and emotions. According to the interpersonal process model of intimacy, emotional self-disclosure predicts interpersonal closeness. However, the specific effects of emotional self-disclosure during conversation on interpersonal closeness and its underlying neural mechanisms remain unknown. This study employed functional near-infrared spectroscopy (fNIRS) hyperscanning to examine speaker-listener dyads during positive and negative emotional self-disclosure and non-disclosure conditions. It measured both individual-level brain activation and group-level interpersonal neural synchronization (INS), as well as functional mechanisms underlying INS. At the behavioral level, we revealed that the self-disclosure group reported significantly higher ratings of interpersonal closeness compared to the non-disclosure group. Furthermore, interpersonal closeness was influenced by gender, with females reporting greater closeness than males. Interpersonal closeness also showed positive correlations with both affective and cognitive empathy. At the individual brain activation level, speakers exhibited greater activation in the inferior frontal gyrus (IFG) and right dorsolateral prefrontal cortex (rDLPFC) during positive relative to negative emotional expression. Additionally, both speakers and listeners showed enhanced activation in the IFG during self-disclosure compared to non-disclosure. At the interpersonal neural synchronization level, increased INS was found in the rDLPFC during self-disclosure relative to non-disclosure. Furthermore, females exhibited greater INS than males under both positive self-disclosure and negative non-disclosure conditions, and we found that INS mediates the effect of empathy on interpersonal closeness, with gender moderating this mediation pathway. In summary, our study reveals that both cognitive and affective empathy jointly enhance interpersonal closeness during emotional self-disclosure. The INS generated in this process significantly predicted closeness, with gender moderating the effect, highlighting distinct neural pathways for intimacy formation, particularly in negative emotional contexts. These findings advance our understanding of the mechanisms underlying interpersonal intimacy and offer new directions for exploring the neural basis of complex social interactions.