ABSTRACT This research concerns the origins and consequences of individual differences in infants' reactions to stress. It is focused on the relation between stress, cortisol release (a physiological indicator of stress), and measures of behavioral distress in infants and toddlers. It involves a longitudinal study between birth and 18 months of age. Adrenocortical and behavioral stress responses will be assess for PKU screening at birth and routine inoculation at 6 and 18 months if age. Maternal caregiving practices and family stress will be assessed when infants are 3 months of age. Quality of mother-infant attachment as well as infant visual self-recognition, self- conscious emotion, and health will be assessed when infants are 18 months of age. The research will inform us not only about infant reactivity to stress using both behavioral and adrenocortical responses, but also the impact of the mother- infant relationship in infant stress reactivity as well as the impact of both infant stress reactivity and he mother-infant relationship in early infancy on subsequent outcomes in the domains of infant health and socioemotional functioning. This information is important both theoretically and practically, and will enrich our understanding of fundamental developmental processes in infancy.
