A lifetime of reading experience facilitates the perception of crowded letters

Visual perception is ordinarily impaired for objects that are tightly crowded by other objects. This might be expected to make reading very difficult given that letters are tightly crowded together within words. However, a lifetime of reading experience may lead to changes in visual processing that reduce the effects of crowding on letters. Study 1 examined this hypothesis experimentally by comparing crowding thresholds (measured as the closest spacing that yields recognition accuracy of 82% correct) for upright letters, inverted letters, and Gabor patches in 60 experienced readers of English. We found that crowding thresholds were reduced for upright letters compared to other stimuli classes, especially for stimuli close to the fovea. In other words, experienced readers could tolerate closer spacing for highly familiar upright letters than for less familiar types of stimuli. Crowding thresholds were also reduced to the right of fixation, matching the left-to-right direction of English reading. Study 2 measured crowding in 250 observers and asked whether individual differences in proxies of reading experience were associated with reduced crowding. We found that higher scores on these proxy measures were associated with lower crowding thresholds for upright letters, especially in the right visual field. These results provide evidence that a lifetime of reading experience alters aspects of visual perception, such that upright letters can be perceived under more-crowded conditions than other stimuli. At a practical level, this means that deleterious effects of letter crowding are significantly reduced for experienced readers, which has implications for both models of visual crowding and reading.