HEART RATE AS A CONVERGENT MEASURE IN CLINICAL AND DEVELOPMENTAL RESEARCH

Abstract

A few years ago we compared infants' reactions to an approach ing stranger in the home and in the laboratory. The behavior codings used at that time were quite coarse: crying, clear behavioral avoid ance or distress, neutral, and positive affect. The overt behavioral data revealed no differences in home versus lab reactions. However, concurrent heart rate (HR) recordings yielded significantly greater HR accelerations in the laboratory (Sroufe, Waters, & Matas, 1974). When we subsequently reviewed the video records of infants whose heart rate and behavioral responses were discordant, we were intent upon resolving the discrepancy in favor of either the HR or the behavioral measures. In fact, this reexamination uncovered subtle aversive reactions in many of the infants whose heart rates acceler ated. For example, we often observed a downward turning away of the eyes (gaze aversion) as the stranger came near. A new coding system was devised which included a wary category. After being trained on a different set of tapes, coders reclassified the infants ac cording to their reactions in the laboratory. With the new codings an association between overt behavioral reaction and heart rate accelera tion was demonstrated (Sroufe et al., 1974). With an even more detailed coding system the association between heart rate accelera tion and wariness was subsequently replicated with an independent sample (Waters, Matas, & Sroufe, 1975). In the second study it was found that while wariness (and, of course, crying) was associated with heart rate acceleration, relatively rare instances of behavioral avoidance (turning the body away from the stranger) were not. It seemed likely that these two negative re actions had different meanings with regard to the infant's adaptation. With gaze aversion there was a precise temporal relationship between overt behavior and autonomic response. Gaze aversion followed heart rate acceleration and, subsequent to gaze aversion, heart rate returned toward basal level. When the heart rate had recovered, the infant again engaged the stranger, sometimes leading to another accelera tion and another look away in the same precisely timed manner