Vagal Regulation and Observed Social Behavior in Infancy

The goal of the present study was to test a recent hypothesis that the ability to suppress cardiac vagal tone during a cognitive challenge was related to social behavior. One hundred thirty-six infants participated with their parents in laboratory visits when infants were 12 (mother visit) and 13 months (father visit) of age. To measure the infants' regulation of cardiac vagal tone, heart rate responses were recorded during the administration of a test of mental development (father visit). Responses to a stranger interaction were measured during the 12 month visit. In addition, experimenters evaluated the infants' behavior across the laboratory sessions using an adaptation of the Infant Behavior Record. Results revealed that infants who were able to suppress vagal tone during the cognitive challenge were rated by the experimenters as more socially approaching at the two laboratory visits. Vagal regulation was unrelated to behavior during the stranger-infant interaction. These findings partially support the hypothesis that infants who are able to regulate their vagal tone have a greater capacity for social engagement.