Research has shown that the quality of mother-infant interactions, such as the way the mother and the infant are in synchrony during interactions, is associated with infants’ vagal tone, a physiological indicator of emotion regulation. However, little is known about the association between the infant’s vagal tone and the quality of father-infant interactions. The existing literature suggests that the greater quantity of time a father spends with the infant, either alone (dyadic time) or with others (social time) may strengthen the association between the quality of father-infant interactions and infant emotion regulation. In this study, we aimed to investigate the association between father-infant synchrony and infants’ vagal tone during interactions and whether dyadic time and social time have a moderating role. Fathers (N = 77) and 3-month-old infants were observed interacting and the infants’ electrocardiogram was recorded to compute indices of vagal tone. Fathers reported dyadic and social time in questionnaires. Results showed that father-infant synchrony has no direct associations with infants’ vagal tone. Moderation analyses revealed that more social time increases the association between synchrony and vagal tone. This study suggests that the interactive processes during shared family time may influence dyadic father-infant interactions and the infant’s vagal regulation.

While research has shown that sensitive and controlling parenting behaviors influence infant development, few studies have used a micro-analytic approach to compare the frequency of occurrence of these behaviors according to parent and child gender, and have examined how these phenomena change during infancy. This study aimed to investigate differences in the frequency of sensitive and controlling behaviors during parent-child play according to parent gender, infant gender, and time. Both parents of 67 families participated in dyadic play interactions when their child was 3 (T1), 9 (T2), and 18 (T3) months old. We took into account four types of behaviors: “observing and validating the infant’s behaviors” and “sharing joint activities with the child” were considered sensitive behaviors, whereas “stimulating the child” and “interfering with the child’s interest” were considered controlling behaviors. Results of generalized linear mixed models showed that mothers at T1 showed more interference than fathers did, whereas parents at T3 observed and validated girls less frequently than they did boys. Time effects showed an increase in interference and joint activities and a decrease in stimulation and observation, which suggests that the type of controlling and sensitive behavior changes as the child develops.