Developmental Changes in the Association Between Heart Rate Variability and Peer Success Across Early Elementary School

Associations between higher baseline heart rate variability (HRV) and better emotion regulation (ER) outcomes are commonly observed among adolescents and adults, but are less consistent among children. It is possible that this association is developmentally emergent, but unclear whether baseline HRV reflects a different functional process in childhood. One possible function could be regulating individuals' openness or susceptibility to environmental influences. The present study tested the effects of a three-way interaction among baseline HRV, teacher–child closeness, and school year (kindergarten, first grade, and second grade) on peer success in a sample of 339 children (M_age = 66.32 months, 70.2% Black, 64.3% male). We examined associations with peer success as indices of age-appropriate development of ER. Two theoretical frameworks were tested developmentally: (1) an ER framework where high baseline HRV would relate directly to greater peer success, and (2) an environmental sensitivity (ES) framework where high baseline HRV would have positive effects on peer success in the context of a positive environment (i.e., high teacher–child closeness), but negative effects in the context of a negative environment (i.e., low teacher–child closeness). Results in kindergarten were partially consistent with the ES framework, whereas in first grade, results tentatively reflected the ER framework. Results suggest that the functional implications of baseline HRV may need to be considered in a developmental context.