Reading in the dark: Effects of age and contrast on reading speed and comprehension

Objective: To explore the effects of contrast reduction on younger and older adults' reading behavior and to examine whether readers rely on word predictability to compensate for poor contrast. Background: Poor contrast can degrade text and may influence reading behavior. Readers may compensate for visual degradation of text by taking advantage of word predictability. Method: In Experiment 1,5 younger and 5 older adults read sentences presented with 10 levels of contrast. In Experiment 2, 40 younger and 40 older adults read high-, medium-, and low-contrast sentences that varied in target word predictability (high vs. low). Results: Relative to those of younger adults, older adults' reading rates were more slowed by low contrast; comprehension was less influenced by contrast (i.e., not significantly). Older adults read high-predictability words faster and comprehended them better than low-predictability words, significantly so for high- and medium-contrast sentences. Younger adults comprehended high-predictability words significantly better than low-predictability words for high- and low-contrast sentences. Conclusion: Low contrast was more detrimental for older adults. High-predictability words benefited older adults by significantly reducing their reading times and benefited all readers by significantly increasing their comprehension. Application: The current findings demonstrate the benefit of adequate contrast and word predictability for optimal text design to facilitate both reading times and reading comprehension.