Effects of intensity, area, and aspect ratio on reaction time to stop lamps.

Abstract

The objective of this study was to investigate the influence of stop lamp intensity, area, and aspect ratio on reaction time. Recent trends in auto body styling have begun to incorporate center high-mounted stop lamps (CHMSLs) into spoilers and trunk lids. These developments, brought on in part by technical advances in automotive lighting, have resulted in questions about the efficacy of stop lamps whose effective luminous area is long and narrow. Subjects in this study were asked to perform a computer-based tracking task to control their eye fixations, and to provide the approximate cognitive loading associated with driving, while responding to the onset of stop lamps of varying characteristics. The results of this laboratory study indicate that aspect ratio and intensity of stop lamps, as well as their interaction, influence reaction time. Specifically, subject reaction times to the onset of simulated stop lamps were longer when the stimulus intensity was low and the aspect ratio was large. These results suggest that further empirical investigation that examines intensity, area, and aspect ratio of stop lamps in the context of the total rear-signaling system is required to determine whether regulation affecting the aspect ratio of stop lamps or CHMSLs is warranted.