Developmental and gender differences in the relationship of behavior pattern to heart rate reactivity between two teenage samples.

The Type A Behavior Pattern was assessed for 122 teenagers from two age-groups. Subjects had their heart rate measured during rest and presentation of a mental arithmetic stressor under timed and competitive conditions. Data were analyzed to determine whether sex, age, task performance, and behavior pattern predicted the degree of heart rate reactivity shown by these children. Although there were no significant main effects for behavior pattern, sex, or age, there was a significant interaction among age, sex, and behavior pattern. It is suggested that the two age groups of teenagers sampled here differ in the relationships they show between behavior pattern and heart rate reactivity. This result challenges some previous assumptions with regard to the homogeneity of teenagers on this issue.