Temperamental and physiological regulatory capacity in infancy: Links with toddler behavior problems.

Although correlates of temperamental regulatory processes in childhood have been well established, there is considerably less work examining correlates and moderators of rudimentary forms of temperamental regulation in infancy. We examined whether infants' physiological regulation indexed via changes in respiratory sinus arrhythmia (RSA) across phases of the Still-Face Paradigm moderated the association between maternal-reported infant regulatory capacity at 8 months (N = 50, Mage = 8.51 months, SDage = 0.28 months, 25 girls) and behavior problems at 14 months. We found that cardiac vagal regulation from baseline to still-face moderated the relation between infant regulatory capacity at 8 months and behavior problems at 14 months. Among infants who displayed relatively high cardiac vagal regulation from baseline to still-face, regulatory capacity was negatively associated with behavior problems. There was no relation between regulatory capacity and behavior problems among infants who displayed average or relatively low cardiac vagal regulation. We speculate that high levels of regulatory capacity and cardiac vagal regulation may allow infants to focus their attention outward and cope with emotionally evocative environmental demands as they arise even in the absence of external regulation provided by their caregivers.