The current report examined the longitudinal relations between cognitive self-regulation, physiological self-regulation, and externalizing problems. At age 4 (n = 98; 49 girls) and 6 (n = 87; 42 girls), children completed the Day-Night task, which taps the inhibitory control dimension of executive function. During the task, cardiac activity was measured and respiratory sinus arrhythmia (RSA) was derived as an index of parasympathetic activity. Mothers reported on externalizing problems. A cross-lagged path model was used to estimate longitudinal predictions while controlling for stability in all constructs over time. Earlier inhibitory control negatively predicted later externalizing problems, but not vice versa. However, RSA reactivity moderated this link; better inhibitory control predicted fewer externalizing problems only when reactivity to the Day-Night task ranged from mild RSA suppression to RSA augmentation. Externalizing problems at 6 years were highest among preschoolers who augmented RSA but showed poor inhibitory control performance, suggesting that risk for psychopathology may be better delineated by viewing self-regulation from an integrated, multi-system perspective.
