Infant resilience to the stress of the still-face: infant and maternal psychophysiology are related.

Respiratory sinus arrhythmia (RSA) is related to infant emotion regulation and resilience. However, few studies have examined RSA of infants and mothers during a stressful experience. Even fewer studies have measured infant and mother skin conductance (SC), which in part reflects anxiety. This pilot study examined RSA, heart rate (HR), and SC patterns of 12 five-month-old infants and their mothers during normal interaction and a stressful perturbation of the interaction in which the mother does not respond to her infant-the Face-to-Face Still-Face (FFSF) paradigm. Dyads were grouped into four categories by two conditions: whether the infant protested to the Still-Face episode (SF) and whether they "recovered" from the SF by reducing protest when the mother resumed interaction in the Reunion (RE). Infants who recovered from the SF had the largest increase in RSA from SF to RE. Mothers of infants who recovered from the SF showed a decrease in RSA during the RE, suggesting mobilization of infant soothing behaviors. Mothers of infants who did not recover from the SF showed physiologic markers of anxiety in the form of continued increases in RSA and high levels of SC. Furthermore, these mothers behaved in a manner that was not responsive to their infant's disengagement cues. These pilot results demonstrate the feasibility of measuring infant SC, a measure long disregarded in infant research. The findings suggest that maternal psychophysiology may be related to infant resilience and suggest a bidirectional effect of maternal and infant reactivity.