THE VISIBILITY OF SYMBOLIC HIGHWAY SIGNS CAN BE INCREASED AMONG DRIVERS OF ALL AGES

Visibility and comprehension of standard text, standard symbolic, and improved symbolic highway signs were compared among young, middle-aged , and elderly observers. The average distance at which standard symbol ic signs could be identified was about two times that of text signs fo r all three age groups. The visibility distances of the improved symbo lic signs, which were designed using an optical blur (i.e., low-pass) approach in order to avoid higher spatial frequencies, exceeded those of both text and standard symbolic signs. Visibility distance was decr eased significantly among older drivers on some signs but not others. There were no significant age differences in the comprehension of symb olic signs. Acuity, a good predictor of visibility distance of both te xt and standard symbolic signs, was only weakly related to the visibil ity distance of the improved symbolic signs. These findings demonstrat e that low-pass symbolic signs have significant advantages in visibili ty over their text counterparts for all drivers.