UC Davis

The visual system is tuned by its inputs. The behavior of reading offers a unique way to examine tuning for visual representations (letters) because readers have massive experience recognizing letters in a systematic context (reading). One aspect of reading is that letters are highly crowded within words, which severely limits their perceptibility. Study 1 demonstrates how the recognition of letters can survive higher degrees of crowding compared to less familiar stimuli like inverted letters or Gabor patches, suggesting letter-specific tuning mechanisms that mitigate effects of visual crowding. This advantage for upright letters was particularly true for spatial locations closer to the fovea and in the right visual field; the locations that are most relied on for reading left-to-right orthographies. Study 2 follows up on this finding and shows that this pattern of reduced crowding for letters was increased for observers who score higher on measures of reading experience, which is also consistent with the idea that reading experience tunes letter representations in specific ways to reduce crowding. Study 3 examines the neural processing of individual upright and inverted letters using a combination of univariate ERP analyses and ERP decoding analyses. It shows that early in visual processing (before 100 ms) ERP decoding for upright letter identity is greater than for inverted letters, suggesting very early tuning for upright letters in the visual system. Further, this early difference was specific to upright letters in the fovea and the right visual field but not for letters in the left visual field. Overall, these behavioral and electrophysiological results illustrate that reading experience shapes the representation of letters in fundamental ways that reflect the constraints that reading puts on the visual system.