PSYCHOPHYSIOLOGICAL MEASURES OF WORKLOAD DURING CONTINUOUS MANUAL PERFORMANCE

Twelve subjects (six female) participated in an experiment designed to separate the effects of perceptual/central and physical demands on ps ychophysiological measures of peripheral nervous system activity. The difficulty of a single-axis continuous manual tracking task was varied in two ways: order of control was manipulated to vary perceptual/cent ral processing demand, and disturbance amplitude was manipulated to va ry physical demand. Physiological measures were sensitive to the impos ition of a task and were more sensitive to physical than to perceptual /central demands. A principal components analysis identified five fact ors (three of them physiological) that accounted for 83.1% of the obse rved variance. Perceptual/central processing demands specifically affe cted the component identified with sympathetic cardiovascular control, whereas physical demands were reflected in the component identified w ith parasympathetic cardiovascular control. This finding suggests that dissociations observed among cardiovascular measures in manual perfor mance tasks are attributable to differential activation of the autonom ic control systems.