Effect of Task Overload Upon Cardiovascular and Plasma Catcholamine Responses in Type A and B Individuals

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Abstract
Cardiovascular and plasma catecholamine effects of task overload were studied in 30 Type A and B subjects. Overload was induced by requiring subjects to work on primary (tracking) and subsidiary (digit recall) tasks simultaneously. On half of the trials, subjects worked on the tasks while listening to high-intensity noise. Overload was expected to be greatest under these conditions, The results showed that the demands of dual-task performance, without the presence of distracting noise, elicited, greater increases in systolic and diastolic blood pressure, and in plasma epinephrine and norepinephrine, in Type A compared to Type B individuals. The addition of noise did not potentiate these differences. Quality of task performance on tracking and recall was similar for the two types of subjects, irrespective of noise exposure. There was, however, an overall recall effect that approached statistical significance, with both A and B subjects doing more poorly on noise than no-noise trials. Correlations between physiologic and performance measures revealed that for B's, greater arousal was associated with enhanced recall scores. For A's, by contrast, level of arousal was unrelated to task performance. These results were discussed in terms of: (1) the facilitation of performance by optimal levels of arousal; and (2) the characteristic propensity of A's for engaging in multiple activities at the same time. Consideration was given to the role of overload-induced sympathetic activation in mediating the enhanced risk of Type A's for coronary heart disease.