Oxytocin moderates father-infant dynamics during triadic family interaction: A dynamic structural equation modeling...

Touch is a primary way parents communicate and bond with infants. Oxytocin, a neuropeptide that promotes bonding and regulates social responsiveness, may shape how parents touch their infants. However, most research has focused on maternal touch in dyadic interactions, leaving fathers and triadic family processes understudied. This study examined second-by-second links between parental touch and infant affect during triadic play with mothers, fathers, and infants.

Sixty-nine families from a longitudinal transition-to-parenthood study were observed during a four-minute triadic free-play task when the infant was six months old (M = 28.7 weeks, SD = 2.3 weeks). Parental touch and infant affect were observationally coded using the Triadic Coding System. Plasma oxytocin was assayed from blood samples taken from parents after the interaction task at the same lab visit. Dynamic structural equation modeling (DSEM) was used to test time-lagged associations between infant affect and parental touch, and whether these links were moderated by parental oxytocin.

Both mothers and fathers showed strong moment-to-moment stability in the intensity of their touch. Parental touch and infant positive affect were bidirectionally associated across time, forming a positive feedback loop. Paternal post-interaction plasma oxytocin (hereafter, oxytocin) moderated these dynamics: fathers who responded to infant positive affect with more vigorous touch showed higher oxytocin levels. No moderation was found for maternal oxytocin. These results only emerged when examining extracted oxytocin, considered the gold standard for reliability.

Findings highlight real-time coordination between parental touch and infant affect and suggest oxytocin may relate to fathers' moment-to-moment responsiveness to infant cues during triadic family interaction.