Abstract
Empathy is a core human capacity that underpins social life. Utilizing hyperscanning electroencephalography (EEG), we tested how empathy to others' distress synchronizes brains without social cues. Mothers and adolescents (study 1, n = 100) underwent empathy-to-distress paradigm in separate rooms. Event-related interbrain connectivity was computed in four 500 ms time-windows following exposure to empathy-to-distress and control stimuli. Interbrain synchrony of fronto-temporal regions emerged throughout (0-2,000 ms) in alpha and beta bands following empathy-to-distress relative to control. Beta interbrain synchrony increased at 1,000-1,500 post-stimuli, indicating neural coupling of higher-order cognitive empathy. Oxytocin and behavioral synchrony correlated with enhanced interbrain synchrony. Study 2 replicated the paradigm with unacquainted adults (n = 44) and found interbrain beta synchrony for empathy stimuli at 1,000-1,500 ms post-stimulus. Exposure to others' distress aligns brains in synchrony. Such alignment may have supported the consolidation of humans into social groups, increased affiliation and trust, and improved joint action to threats, enhancing survival and thriving.