Effect of Level of Challenge on Pressor and Heart Rate Responses in Type A and B Subjects1

The present study examined the relationship between the Type A coronaryprone behavior pattern and the magnitude of cardiovascular response induced by varying levels of environmental challenge. In a 2 × 2 experimental design, Type A and B (noncoronary‐prone) subjects ( n = 80) were randomly assigned to either high or low challenge instructional conditions for both the cold pressor (CP) and a choice reaction time task (RT). Overall, across both tasks, Type A subjects responded with greater systolic blood pressure (SBP) and heart rate (HR) elevation than Type B subjects. While these differences between the Types tended to be larger in the high challenge condition, some differences were also observed under low challenge. Component analyses of the Pattern revealed that high hostile/competitive Type A's responded to both low and high challenge instructions in the CP and RT tasks with physiologic elevations comparable to that displayed by globally defined Type A's receiving high challenge instructions. The present findings tentatively suggest that (a) high hostile/competitive Type A's respond to even mild challenge with enhanced physiologic response; (b) globally defined A's tend to evidence the physiologic elevations when specifically challenged; and (c) Type B's show much smaller physiologic reactions to such challenges. Consistent with previous research, comparison of Type A assessment techniques revealed that the Rosenman diagnostic interview was a better predictor of physiologic response than other questionnaire methods. Two hypotheses are advanced and future research recommended regarding possible relationships between environment, behavior, physiology, and disease.