The prism of reactivity: Concordance between biobehavioral domains of infant stress reactivity

Across a range of challenging contexts, a complex system of stress responses within multiple domains (e.g., behavior, physiology) support, or thwart, an infant’s capacity to navigate an ever-changing world. As understanding of these individual stress response systems has improved, researchers have called for integrated examinations across multiple systems and domains. However, extant research has usually focused on reactivity within a single system and very few explore the associations between multiple domains of stress responding. Drawing on a diverse sample of 135 mother-infant dyads, the current study explored biobehavioral concordance across the Autonomic Nervous System (ANS; measured via both cardiac and salivary indicators), Hypothalamic-pituitary-adrenal (HPA; measured via salivary indicators) axis, observed behavior, and maternal reports of temperament. Correlation analysis generally revealed moderate negative associations between ANS and HPA axis, moderate negative associations between ANS and coded negative behavior, and small-to-moderate positive associations between ANS and coded object engagement and social behavior. Salivary biomarkers and maternal report of infant temperament showed less concordance across systems and domains than cardiac ANS indicators. These findings provide a foundational understanding of the associations between biobehavioral indicators of stress responses in infancy, a period of high developmental plasticity. •Little is known about how stress responses system work together during infancy when these systems have increased plasticity.•Our findings point to a strong connection between cardiac ANS and coded behavior across rest and reactivity phases.•Salivary biomarkers and infant temperament showed less concordance across systems and domains than cardiac ANS indicators.•Utilizing multiple measures of “reactivity” across domains may provide a more holistic view of infant regulation.