Physical Versus Psychological Determinants of Heart Rate Reactivity to Mental Arithmetic

ABSTRACT The feasibilty of partitioning heart rate response to a psychosocial streesor into physical versus psychological components was brought under experimental scrutiny. Two tasks were performed in a counterbalanced order. The psychological task consisted of a set of mental arithmetic problems for which verbal answers were requested. The physical task mimicked the speech demands of the psychological task but required no arithmetic processing. Heart rate increased significantly over baseline during both psychological and physical task but there was a greater increase seen with the former. During both tasks, heart rate attained peak levels at about 50s into the tasks and then declined. Degree of reactivity to the two tasks was correlated.Subjectively, the physical task was assesed as possessing almost no difficulty whereas the psychological task had intermediate difficulty. Since the physical demands of response verbalization may account for a substantial portion of the total reactivity to a psychosocial strssor, greater attention to precise identification of reactivity determinats may be indicated.