Respiratory Synchrony and Individual Differences Causally Influence Dyadic Interpersonal Coordination

Human interpersonal coordination can yield synchronization at multiple timescales, including behavioral (auditory-motor) and physiological (respiratory and cardiac) levels; yet the causal relationship among these levels is poorly understood. We examine dyadic synchronization at behavioral (tone onsets) and physiological (respiratory and cardiac) levels in music performance, a rhythmic task that requires fine temporal coordination among performers. By perturbing dyads' auditory-motor synchrony or their respiration during joint melody perception and production, we demonstrate the directional influence from dyadic respiration synchrony to behavioral synchrony. Respiratory perturbations impaired both dyadic respiratory and behavioral synchrony, whereas auditory-motor perturbations disrupted only dyadic behavioral synchrony. Furthermore, individual differences influenced dyadic synchrony: partners with similar spontaneous production rates achieved better behavioral synchrony in joint production, and partners with similar resting heart rates exhibited stronger cardiac synchrony in joint production. These findings reveal directional entrainment processes between respiratory and behavioral synchrony, and highlight the pivotal role of individual differences in interpersonal coordination.