Narrative alignment: how ways of sharing personal stories modulate brain-to-brain synchronization

Sharing personal life stories fosters close relationships and enhances mental wellbeing. When recalling negative experiences, individuals often engage in counterfactual reconstruction-imagining how events could have unfolded differently (eg "If only…"). This study used fNIRS hyperscanning to examine how different storytelling modes influence interpersonal neural synchronization (INS). Dyads (n = 114) took turns speaking and listening while recounting negative experiences either factually (Real-Memory retelling, RM) or counterfactually (Counterfactual Reconstruction, CF). Participants were assigned to a no-feedback (monologue) or feedback (interactive dialogue) condition. In the no-feedback group, RM elicited stronger INS than CF between the speaker's right dlPFC (dorsal lateral prefrontal cortex) and the listener's left dlPFC/FPC (frontopolar cortex)-regions involved in executive control-whereas CF elicited stronger INS than RM from the speaker's left temporal parietal junction (TPJ) (mentalizing) to the listener's left dlPFC. In the feedback group, CF elicited weaker INS than RM from the speaker's left TPJ to the listener's left dlPFC. Additionally, INS during CF was positively correlated with the emotional empathy scores of the more empathic partner in each dyad. These results suggest that INS patterns reflect distinct cognitive and social demands of factual vs. counterfactual storytelling and are modulated by empathy. We propose that such neural alignment underpins a shared workspace supporting interpersonal communication.