The effects of age-related changes in vision on performance in reading from electronic displays

The effects of display luminance, contrast, and stroke-width of the characters of a liquid-crystal display (LCD) on performance in reading were measured for groups of young (N=25, mean age 21.2 years) and old (N=25, mean age 68.6 years) subjects. Reading rates were from 14 to 22% lower for subjects in the 'old' group. These differences between the young and old groups were greater for the conditions of low display luminance and contrast than for the conditions of high display luminance and contrast. We also measured the contrast sensitivity functions and visual acuity for near and distant objects in the two groups. The contrast sensitivities at a high spatial frequency and close-range acuity for the old group were significantly lower than those for the young group. Within the young group, no evidence was found for a significant correlation between any of the measured variables and the rate of reading. However, within the old group, the correlation between contrast sensitivity at a high spatial frequency and rate of reading were significant. These results indicate that contrast sensitivity plays a role in limiting the speed of reading. Age-related changes in the high spatial frequency contrast sensitivity will thus result in slower reading from displays with lower luminance or contrast. Requirements for electronic displays in terms of reading by older users were also discussed.