Effects of illumination, viewing distance, and lighting color on perception time

A laboratory study was carried out to investigate the effects of illumination, viewing distance, and lighting color on perception time with center high-mounted stop lamps comprised of light-emitting diodes. Analysis indicated that illumination, viewing distance, and lighting color are significant factors in perception time. Low illumination resulted in shorter perception time than high illumination. A viewing distance of 20 m resulted in shorter perception time than 40 m. The perception time was shorter for blue than for red or yellow light. The interaction of illumination and lighting color was significant. Mean difference in perception time among lighting colors was not significant under low illumination, but was significantly shorter for blue light under high illumination. Based on the results, blue light seemed to be the optimal lighting color for center high-mounted stop lamps comprised of light-emitting diodes.