Mental integration and emotional resonance: The relationship between self-other overlap and intimate relationship...

Self-other overlap (SOO), as a core cognitive representation in intimate relationships, significantly influences relationship satisfaction. Grounded in Self-Expansion Theory and the Interpersonal Process Model, this research systematically examines the behavioral and neural pathways through which SOO affects intimate relationship satisfaction via three studies. Study 1 (67 couples) investigated the relationship between SOO, emotional synchrony, and intimate relationship satisfaction through an emotional synchrony experiment. Studies 2 (51 couples) and 3 (36 couples) employed EEG hyperscanning technology to measure prefrontal interpersonal neural synchronization (INS) during independent and interactive emotional synchrony tasks, respectively. These studies further explored the mediating role of INS between SOO and relationship satisfaction. Results revealed that: At the behavioral level, SOO significantly and positively predicted intimate relationship satisfaction, with emotional synchrony acting as a partial mediator. At the neural level, prefrontal INS was significantly negatively correlated with intimate relationship satisfaction. INS partially mediated the relationship between SOO and relationship satisfaction. These findings suggest that partners with high SOO rely on mature, coordinated interaction patterns, thereby reducing the need for real-time neural synchronization and optimizing neural resource allocation. In contrast, partners with low SOO compensate for weaker emotional bonds by enhancing INS; however, this high-energy neural coupling is associated with lower relationship satisfaction. This research provides novel perspectives and empirical evidence for understanding the intrinsic mechanisms of intimate relationships.