Abstract
A method to prevent driver's drowsiness during a monotonous driving task was investigated. Since drowsiness, a lower state of vigilance, is associated with reduced activity of the cerebral cortex, it may be possible to maintain vigilance by providing a proper environmental stimulation to the driver. Intermittent-sounds were chosen as the stimulation means and their effects on vigilance change was investigated. It was found that such intermittent-sounds had effects of maintaining vigilance during monotonous tasks. This approach to prevent drowsiness would be beneficial in that it neither requires driver's efforts nor interfere with driving maneuvers.