Laboratory reactivity assessment: effects of casual blood pressure status and choice of task difficulty

In a study of 60 healthy young men, 26 with high and 34 with normal casual systolic pressure, blood pressure and its underlying hemodynamic determinants were measured at rest and during exposure to a series of laboratory tasks. Subjects were given a choice of performing either a difficult or an easy version of a mental arithmetic task, and then offered a similar choice of an easy or difficult stimulated public speaking task. All subjects were given the same tasks, regardless of choice, but led to believe the tasks were the ones they had chosen. During all tasks, subjects with high casual systolic pressure showed greater blood pressure, cardiac output, heart rate and myocardial contractility increases than subjects with normal casual pressure. Within the high casual pressure group, subjects who chose difficult for the mental arithmetic task exhibited greater increases in systolic pressure and heart rate during that task than subjects who chose easy. This subgroup maintained their greater responses during a subsequent mental arithmetic task in which all subjects were told that the difficulty level was the reverse of what they had initially chosen. Choosing difficult on the speaking task was associated with greater increases in cardiac output during performance on that task. Differences in cardiovascular responses associated with choice of difficulty were not evident during performance on tasks which did not pertain to the choice. For mental arithmetic, choice of difficulty was also associated with the psychological trait, fear of failure. These findings are relevant to the development of cardiovascular reactivity assessment procedures, which should attempt to detect psychological as well as physiological determinants of individual differences.