Left-lateralized early neurophysiological response for Chinese characters in young primary school children

Adult readers consistently show an enhanced early event-related potential (ERP) response, N170, for visual words compared with other stimuli at left posterior electrodes. Developmental studies with words in alphabetic languages showed that this neurophysiological specialization for print develops rapidly from 6 to 10-years of age and becomes established around 10-11 years of age. Here we report for the first time the development of the word-related N170 in Chinese children learning to read Chinese, a logographic writing system radically different from alphabetic scripts in visual and linguistic features. We recorded ERP responses elicited by Chinese characters and line drawings of common objects in three groups of primary school children at 7, 9, and 11 years of age as well as college students. Results showed that the amplitude of N170 evoked by Chinese characters in the 7-year-old group was significantly larger than that in the 11-year-old group and the adult readers. Remarkably, all four age groups - even the youngest group - showed an increased and left-lateralized N170 response for Chinese characters, as compared with line drawings, suggesting that a relatively specialized mechanism for processing Chinese characters is already emergent by as early as 7 years of age. Our results, combined with studies of non-Chinese child readers suggest that the developmental pattern of word-related N170 is highly similar across different scripts, possibly reflecting increased visual processing expertise that children acquire through everyday reading.