Physiological synchrony is defined as reciprocal and coordinated physiological activity between partners during social interaction (Feldman, Magori-Cohen, Galili, Singer, & Louzoun, 2011). From infancy, parent and child begin to show coordinated physiological states through timely adaptation to each other's signals (e.g., vocalization, touch). Parent-child synchrony provides children with the opportunity to match their biological rhythm and physiological states with parents in a coordinated manner, which facilitates shared-timing and coregulation among parents and children. In turn, physiological synchrony has been proposed to serve as a foundation for children's emerging abilities for attachment, social bonding, and emotion regulation, which shape the lifelong development of socioemotional competence (e.g., empathy; Feldman, 2007). Toward this, empirical research on parent-child synchrony has examined physiological synchrony in different age groups (e.g., young children, Lunkenheimer et al.