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Alan Chun-Nang, Tim Curran, Brion Woroch, Isabel Gauthier; N170 associated with expertise in letter perception. Journal of Vision 2004;4(8):519. doi: 10.1167/4.8.519.
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© ARVO (1962-2015); The Authors (2016-present)
Expertise with print is likely to optimize visual processes for recognizing characters of a familiar writing system. An example is the increase in sensitivity to changes in fonts (e.g., Sanocki, 1987; Wong & Gauthier, VSS'03). While brain activations have been identified for words and letter strings compared to other stimuli, relatively little work has focused on the neural basis of single letter perception. To investigate this we recorded event-related potentials for Chinese-English bilinguals and English readers. They viewed letters and 5-letter strings, and performed 1-back identity judgment by pressing a key whenever a letter was identical to the immediately preceding one, or when the middle letter of a string was identical to the middle letter of the immediately preceding string. Six types of stimuli (Roman, Chinese or pseudofont characters, shown either alone or in strings of 5 characters) appeared in separate blocks. The Chinese-English bilinguals showed an enhanced N170 for individual Roman letters and Chinese characters compared to pseudofonts. For the English readers, the N170 amplitude was larger for Roman letters relative to Chinese characters and pseudofonts. Interestingly, the familiarity-related enhancement of the N170 for single characters was not obtained for Roman strings, similar to a finding in a left anterior fusiform gyrus area obtained in fMRI (James & Gauthier, HBM'03). Our results reveal that changes in relatively early visual processes underlie expert letter perception. Up to now, single letter recognition has not been the focus of object recognition or reading studies, but our results suggest that it may be an important avenue for future studies.
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