Reading speed and comprehension are both critical factors for many common activities, such as interpreting highway signs and medication warnings. Poor contrast can degrade text, leading readers to compensate for the visual degradation by taking advantage of word predictability. This paper explores the effects of contrast reduction on younger and older adults' reading behavior and examines whether readers rely on word predictability to compensate for poor contrast. In the first experiment, 5 younger (22-25 years of age) and 5 older adults (68-77 years of age) read sentences presented with 10 levels of contrast. In the second experiment, 40 younger and 40 older adults read high-, medium-, and low-contrast sentences that varied in target word predictability (high vs. low). Results showed that older adults' reading rates were more slowed by low contrast compared to those of younger adults. Comprehension was not significantly influenced by contrast. 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. The current findings demonstrate the benefit of adequate contrast and word predictability for optimal text design.
Abstract