Letter case and text legibility in normal and low vision.
It is thought by cognitive scientists and typographers alike, that lower-case text is more legible than upper-case. Yet lower-case letters are, on average, smaller in height and width than upper-case characters, which suggests an upper-case advantage. Using a single unaltered font and all upper-, all lower-, and mixed-case text, we assessed size thresholds for words and random strings, and reading speeds for text with normal and visually impaired participants. Lower-case thresholds were roughly 0.1 log unit higher than upper. Reading speeds were higher for upper- than for mixed-case text at sizes twice acuity size; at larger sizes, the upper-case advantage disappeared. Results suggest that upper-case is more legible than the other case styles, especially for visually-impaired readers, because smaller letter sizes can be used than with the other case styles, with no diminution of legibility.
Arlene R. Gordon Research Institute, Lighthouse International, 111 East 59th Street, New York, NY 10022, USA. arditi@lighthouse.org
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D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D006801:Humans; D010364:Pattern Recognition, Visual; D011327:Printing; D011932:Reading; D012684:Sensory Thresholds; D013997:Time Factors; D015354:Vision, Low / Q000503:physiopathology / Q000523:psychology*; D014792:Visual Acuity