Empathy in psychotherapy: subjective ratings versus remote biosensing of interpersonal heart rate synchrony as outcome predictors

In addition to understanding empathy in an affective and cognitive dimension, the physiological domain plays a crucial role, especially in the emotional dynamics of interpersonal interactions during psychotherapy. Within the complex bio-psycho-social system of cognitive behavioural therapy language, cognition, emotion and physiological states of both, client and therapist, intertwine through interaction dynamics. The current study aimed to explore interpersonal physiological dynamics during psychotherapy sessions as an objective biomarker for predicting therapy outcome. In a follow-up assessment design, involving 25 client-psychotherapist dyads, wearable sensors monitored individual’s heart rate, while video cameras recorded movement behaviour during regular cognitive behavioural therapy sessions. Post-session reports and symptom questionnaires were collected from both, clients and therapists, after each session. Results showed that synchrony in head movement and heart rate emerged during psychotherapy sessions. Notably, heart rate synchrony from the initial session predicted changes in patients’ self-rated global severity index over time. The objective predictor, heart rate synchrony, emerged as particularly robust, surpassing patients’ subjective ratings of affiliation in explaining a higher variance of the therapy outcome variable. These findings highlight the potential shown by remote biomarker sensing of interpersonal dynamics for the prediction of psychotherapeutic effectiveness.