Physiological correlates of stress-induced decrements in human perceptual performance.

Abstract

Stress-induced changes in human performance have been thought to result from alterations in the multidimensional arousal of the individual, as indexed by alterations in the physiological and psychological mechanisms controlling performance. Identification of such changes in substrate activities provide more complete descriptions of both the performance changes and the arousal state/mechanisms. In this study, decrements in perceptual performance were produced by independent and combined administration of atropine, sleep loss and exercise for both a visual aircraft identification task and an auditory vigilance task; measurements of performance changes were accompanied by state measures of cardiovascular function, pupillary diameter, sleep onset latency, and subject self-reports. Observed performance changes were accompanied by monotonic increases in heart rate after atropine and exercise, but not sleep loss. Moderate exercise produced blood pressure changes indicative of physical workload, but only atropine increased diastolic blood pressure and pupillary diameter relative to performance effects. Atropine and sleep loss each reduced sleep onset times to less than 50 percent control values; when combined with exercise, sleep onset times were reduced further. These reductions in general arousal were confirmed by subject self-reports of reduced attentiveness and competence. These state measures of organismic function were found to be discriminatively correlative, but not predictive, of the decrements in perceptual performance seen; however, practical combinations of appropriate real-time measurement techniques could be developed that would promote the telemetering of human physiological activity to signal performance breakdown.