Growth models of dyadic synchrony and mother–child vagal tone in the context of parenting at-risk

• Changes in RSA and positive synchrony were modeled over time in mother–child dyads.
• History of child maltreatment associated with lower positive synchrony.
• Growth models of maternal RSA related to extent of positive synchrony.
• Greater positive synchrony associated with larger RSA responsivity in mothers.

We used multilevel modeling to examine dynamic changes in respiratory sinus arrhythmia (RSA) and observer-coded interactive synchrony for mother–child dyads engaged in a laboratory interaction, to characterize parenting-at-risk. Seventy-nine preschooler–mother dyads including a subset with documented child maltreatment (CM; n = 43) were observed completing a joint puzzle task while physiological measures were recorded. Dyads led by CM mothers showed decreases in positive synchrony over time, whereas no variation was observed in non-CM dyads. Growth models of maternal RSA indicated that mothers who maintained high levels of positive interactive synchrony with their child evidenced greater RSA reactivity, characterized by an initial withdrawal followed by augmentation as the task progressed, after accounting for CM group status. These results help to clarify patterns of RSA responding in the context of caregiver–child interactions, and demonstrate the importance of modeling dynamic changes in physiology over time in order to better understanding biological correlates of parenting-at-risk.