The goal of the present study was to examine how quality of the child-caregiver attachment relationship related to children's cardiac vagal reactivity in response to a novel social stressor. Children's (N = 48; M age = 3 years 9 months) cardiac data were collected as they participated in an ambiguous and potentially threatening social situation together with their mothers. Their degree of behavioral inhibition also was observed. Attachment classifications were assessed separately. Children classified as Secure showed vagal withdrawal from baseline to the stressor, whereas children classified as Ambivalent did not show vagal withdrawal in response to the stressor. There was a marginally significant moderation of attachment-related differences in vagal withdrawal by level of behavioral inhibition. Among highly behaviorally inhibited children, those classified as Ambivalent demonstrated little or no vagal withdrawal compared to their Secure counterparts. In contrast, no attachment-related differences were found among those who appeared less behaviorally inhibited. Findings are discussed in relation to children's emerging self-regulation skills in the context of their attachment relationship.
Keywords: attachment; behavioral inhibition; cardiac vagal tone; physiology.