A systematic review of hyperscanning in clinical encounters

Therapeutic alliance is defined as the collaborative relationship between patient and therapist. Strong therapeutic alliances have been associated with positive clinical outcomes, but much remains unknown about alliance and its physiological basis. Interpersonal neural synchrony (INS) - the synchronization of neural signals between interacting individuals - is emerging as a novel lens for studying interactions with relatively objective and time-sensitive neuroimaging techniques. We searched four databases to identify studies of INS in clinical encounters. Our search yielded 161 articles, 46 met criteria for full-text review and 11 were included. The included articles reported INS across a total of 160 dyads, all published since 2018. Despite diverse methodologies, INS was observed in all studies and was often related to therapeutic outcomes. However, results were mixed regarding associations between INS and therapeutic alliance. These results highlight that, while promising, additional research is needed to elucidate the relationship between INS, therapeutic alliance and clinical outcomes. Future studies should aim to standardize methodologies, explore temporal dynamics (e.g., through longitudinal assessments), and include larger sample sizes.