Nighttime Conspicuity of Highway Signs as a Function of Sign Brightness, Background Complexity and Age of Observer

Abstract

The introduction of ultrabright retroreflective materials may provide the opportunity to develop highway signs with improved conspicuity — especially when viewed in highly complex (i.e., “cluttered”) driving environments. In order to investigate this possibility, the glance conspicuity of briefly presented highway signs was examined as a function of sign brightness (bright vs. ultrabright), background scene complexity (low, moderate, high) and age of observer (young vs. old). Glance conspicuity — measured in terms of both reaction time and accuracy — was found to improve as a function of increased sign brightness when viewed against high complexity (but not low complexity) backgrounds. These findings are discussed in terms of their implications for improved design of traffic control devices.