Environmental Stressors as Causal Factors for Driver Fatigue

Abstract

The purpose of the investigation was to evaluate the relative effects of a moderate or suboptimal level of environmental heat and noise stress on individuals by utilizing performance and nonperformance parameters.

Twenty-five male undergraduate and graduate students attending West Virginia University volunteered as subjects for this laboratory study. Each subject was isolated in a specially constructed chamber. Heat and noise were designated as the two independent variables used in the investigation. The effects of both variables on five dependent measures were evaluated for a nonstress condition and for a stress condition. Four physiological variables, which included heart rate, heart rate variability, galvanic skin response, and 17-hydroxycorticosteroid level were used to assess the level of psychophysiological arousal or activation attributed to the heat and noise stress. Task performance was measured in the form of reaction time to a visual stimulus.

The data analyses revealed the influential effects of the two environmental test conditions. Relative to the nonstress condition, values for heart rate, heart rate variability, galvanic skin response, and 17-hydroxycorticosteroid level were significantly greater for the stress condition. Continuous exposure to the stress condition precipitated an increase in the level of psychophysiological arousal. Reaction times to the visual display were significantly greater for the stress condition than for the nonstress condition. The decrement in task performance occurred cumulatively over the duration of the experiment.