The social, decoupled self: interpersonal synchronization of breathing alters intrapersonal cardiorespiratory coupling

People synchronize their behavioural and physiological rhythms with each other during social interaction. While interpersonal synchronization has largely been associated with positive effects such as social bonding, some evidence suggests that it may also impair self-regulation and disrupt intrapersonal coordination. Because respiration and heart rhythms are weakly coupled within individuals, we investigated whether synchronizing breathing with another person alters intra-personal cardiorespiratory coupling. Across two experiments, participants synchronized their breathing reciprocally (bidirectional interaction), unidirectionally with a confederate, or with pre-recorded breathing signals, while respiration and electrocardiography (ECG) were continuously measured. Relative phase analyses revealed that bidirectional breathing synchronization induced in-phase synchronization of heart rhythms between individuals. Critically, interpersonal synchronization coincided with cardiorespiratory decoupling: respiration and heart rhythms became more out-of-phase during interaction compared to resting baselines and the unidirectional condition. Moreover, stronger interpersonal respiratory synchronization predicted greater intra-personal cardiorespiratory decoupling, particularly when participants adapted their own breathing to another persons. These findings provide evidence that interpersonal physiological synchronization entails a trade-off with intra-personal physiological coupling, perturbing the phase relationship within ones own physiological system. We propose that aligning ones physiological rhythms with others strengthens self-other coupling but weakens intrapersonal coupling, pointing to a physiological mechanism of self-decoupling during social interaction. Graphical abstractWhen two people synchronize their breathing together, their heart rhythms also synchronize, while their intrapersonal cardiorespiratory rhythms become decoupled, with a perturbed phase-relationship between respiration and cardiac rhythms. Across two experiments, stronger interpersonal respiratory synchronization was associated with more pronounced intrapersonal cardiorespiratory decoupling. These findings suggest a physiological trade-off: aligning bodily rhythms with others strengthens self-other coupling, but may coincide with a phase shift in ones intrinsic cardiorespiratory rhythm. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=96 SRC="FIGDIR/small/679159v2_ufig1.gif" ALT="Figure 1"> View larger version (16K): org.highwire.dtl.DTLVardef@17e4675org.highwire.dtl.DTLVardef@143bf94org.highwire.dtl.DTLVardef@d6b841org.highwire.dtl.DTLVardef@dab5e2_HPS_FORMAT_FIGEXP M_FIG C_FIG