PSYCHOPHYSICAL DETERMINANTS OF STRESS IN SUSTAINED ATTENTION

To date, research on the stress of sustained attention tasks has not e xplored the extent to which such stress is determined by the psychophy sical aspects of the monitored display. In the present study, the effe cts of the sensory modality of signals (audition and vision) and the b ackground event rate (5 and 40 events/min) on task-induced stress were examined in a vigilance situation. Critical signals for detection wer e slight changes in stimulus duration. Stress was indexed by motor res tlessness and subjective reports of fatigue. Restlessness and subjecti ve fatigue increased dramatically across a 50-min watch in all conditi ons. Stress effects were most notable in the case of visual monitoring but were unrelated to variations in event rate. Hence, from a psychop hysical perspective, the stress of sustained attention seems to be ide ntified more specifically with the sensory modality of signals than wi th the event rate context in which they appear.