The Self and Its Intersubjective Synchrony in Psychotherapy: A Systematic Review

The self is pivotal in psychotherapy, integrating internal (interoexteroceptive) and external exteroproprioceptive) layers of experience necessary to create an intersubjective space in psychotherapeutic relationship to foster self-reorganization. Patient–therapist intersubjective experience of synchrony seems to be core in better alliance and connectedness, favouring therapeutic progresses. However, the biobehavioural aspects of intersubjective synchrony are often disconnected from the self, leaving gaps in understanding its role in shaping therapy processes and outcomes. Following PRISMA guidelines, 32 studies measuring intersubjective synchrony during psychotherapy sessions were identified, covering interoexteroceptive (n = 11), exteroproprioceptive (n = 18) and interbrain (n = 4) synchrony. Exteroproprioceptive synchrony, particularly nonverbal, was primarily associated with the therapeutic alliance: This was further supported by interbrain studies, whereas interoexteroceptive synchrony was mainly linked to moment-to-moment emotional experience. On the other hand, we found mixed findings on the associations of exteroproprioceptive synchrony with overall therapy outcomes, whereas interoexteroceptive synchrony seemed to be positively associated with session-level outcomes. Moreover, pre-session intra-subjective traits (e.g., patients' well-being and psychopathology, therapists' attachment and expertise) influenced intersubjective synchrony patterns. Finally, we found that degrees of synchrony varied across patients suggesting different experiences of optimal psychotherapeutic relationship. Findings highlighted the layered dynamics of synchrony in psychotherapy. Achieving effective therapeutic engagement involves balancing context-sensitive synchrony at different layers through intersubjective interaction for a self-reorganization of the patients' dynamics. Future research should further explore how distinct layers and dynamics interact both at intrasubjective and intersubjective levels. A spatiotemporally informed emphasis on self-related dynamics can illuminate common therapeutic factors and clarify their role in short- and long-term outcomes