Preventive safety by auditory-vibrotactile automotive warning system-Effectiveness of auditory-tactile automotive warning that makes the most of advantages of auditory and tactile modalities

The aim of this study was to identify a more effective condition when providing warning with drivers. The type of auditory stimulus and the type of tactile stimulus were within-subject experimental variables. The auditory stimuli were looming sound, pure tone, and car horn. The tactile stimuli were simultaneous two-point stimulation, stimulation by apparent movement, and two-stimulation by apparent movement. The participants were required to carry out a simulated driving task, speed keeping operation by adjusting a foot pedal, and a judgmental task of hazardous situation from four directions (front, rear, left, and right). No significant differences of reaction time were detected among three types of auditory stimuli, and among three types of tactile stimuli. As for the false reaction to the catch trial, the combination of the looming sound and the 2-stimulation by apparent movement led to fewer false reactions than other combinations, which suggested the effectiveness of the combination of the looming sound and the 2-stimulation by apparent movement.