This project focuses on long-term consequences of individual differences in physical, social, and affective functioning. In one study, we found stable individual differences in positive and negative responding to a series of emotion-eliciting stimuli as well as in heart rate and vagal tone. Cortisol levels became more individually characteristic over time and varied as a function of diurnal rhythms. Although mothers' perceptions of infant temperament were also highly stable, they were unrelated to observational measures of facial expressiveness or physiological reactivity. Measures of behavioral synchrony in the home predicted differences in the subsequent security of attachment. In a second project, we are studying infant-mother interaction and attachment in infants from upper-middle class Euro- Americans and lower-class Central American families, developing culturally-sensitive criteria for evaluating normative social behavior and development. Regardless of social or ethnic background, mothers spent comparable amounts of time in discrete activities such as feeding, caring for, and playing with their infants.
