Three experimentes were conducted to investigate the effects of adult aging upon the legibility of simulated symbol highway signs. Each experiment employed a different set of lighting conditions: (1) daytime luminance; (2) nighttime luminance; and (3) nighttime luminance with glare. Young (ages 18-25) and middle-aged (ages 40-55) observers demonstrated small reductions in legibility when luminance was reduced from daytime to nighttime levels. However, older (ages 65-79) observers demonstrated marked losses in legibility distance with reductions in sign luminance. The introduction of a glare source (equivalent to approaching automobile headlights at 30 m) reduced sign legibility distance for the older observers but had no deleterious effect upon their young and middle-aged couterparts. The relative magnitude of the observed age, luminance and glare effects appeared to be equivalent across all signs examined.
Samenvatting