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 symbolic signs could be identified was about 2 times that of text signs for all age groups. The visibility distances of the improved symbolic signs, which were designed using an optical blur approach in order to avoid higher spatial frequencies exceeded those of both text and standard symbolic signs. Visibility distance was decreased signifcantly among older drivers on some signs but not others. There were no significant age differences in the comprehension of symbolic signs. Acuity, a good predictor of visibility distance of both text and standard symbolic signs, was only weakly related to the visibility distance of the improved symbolic signs. The findings demonstrate that low-pass symbolic signs have significant advantages in visibility over their text counterparts for all drivers.
Samenvatting