Abstract
The visibility distance for young middle-aged, and elderly observers of text and icon versions of 4 different highway signs were compared under day and dusk lighting conditions. No age differences were observed. Icon signs, however, were visible at much greater distances than were text signs, but there was considerable variability from one icon sign to another in the degree to which they were comprehended. Acuity was found to be a better predicter of the visibility distance of text signs in both day and dusk conditions than it was of icon signs. To the degree that they are comprehended, icon sings appear to offer drivers of all ages almost twice as much time in whichto respond to them.