Comprehension of Warning Symbols by Younger and Older Adults: Effects of Visual Degradation.

The goal of this study was to investigate the effects of visual degradation on warning symbol comprehension across warning symbol types and age groups. Twenty-seven black and white ANSI symbols of four different types (prohibition, course of action, information, and hazard symbols) were presented to older (N = 21, M = 73.1) and younger adults (N = 20, M = 21.4) via computer at three degradation levels (0%, 30%, 40% of pixels inverted); accuracy and response time in answering yes-no questions about the symbols were recorded. Younger adults were more accurate and faster overall than older adults (p < .01). Regarding degradation, 0% and 30% inverted symbols did not significantly differ in comprehension (p ≥ .25), but both were comprehended better than 40% inverted symbols (p < .01); no interactions were observed. For degraded warning symbols, results suggest symbols must be substantially degraded to affect base comprehensibility, and age differences exist. These data have practical implications for warnings in environments susceptible to degradation.