Abstract
The relationship between visual and auditory display qualities and drivers' abilities to detect criticality and urgency were experimentally examined, and the interval scales were obtained for each quality determinant, i.e. color-luminance, temporal and spatial characteristics of the visual displays and sound pressure, frequency and temporal characteristics of the auditory displays. The effect of the experimentally set displays and the relative contributions of the display characteristics were clarified on identical scales for each of the visual and auditory displays. Furthermore, the combining effects of the determinants were also estimated.