Social Touch is associated with Neural but not Physiological Synchrony in Naturalistic Mother-Infant Interactions

Abstract

Caregiver touch plays a vital role in infants growth and development, but its role as a communicative signal in human parent-infant interactions is surprisingly poorly understood. Here, we assessed whether touch and proximity in caregiver-infant dyads are related to neural and physiological synchrony. We simultaneously measured brain activity and respiratory sinus arrhythmia of 4- to 6-month-old infants and their mothers (N=69 dyads) in distal and proximal joint watching conditions as well as in an interactive face-to-face condition. Neural synchrony was higher during the proximal than during the distal joint watching conditions, and even higher during the face-to-face interaction. Physiological synchrony was highest during the face-to-face interaction and lower in both joint watching conditions, irrespective of proximity. Maternal affectionate touch during the face-to-face interaction was positively related to neural but not physiological synchrony. This is the first evidence that touch mediates mutual attunement of brain activities, but not cardio-respiratory rhythms in caregiver-infant dyads during naturalistic interactions. Our results also suggest that neural synchrony serves as a biological pathway of how social touch plays into infant development and how this pathway could be utilized to support infant learning and social bonding. HighlightsO_LIMother-infant neural and physiological synchrony arise during mutual engagement. C_LIO_LIBehavioral correlates of neural and physiological synchrony diverge. C_LIO_LIInterpersonal neural synchrony is related to proximity and affective touch. C_LIO_LIInterpersonal physiological synchrony is related to infant negative affect. C_LI