Co-author Wai Ting Siok of the University of Hong Kong said that for speakers of English, dyslexia is basically a phonological disorder -- a problem detecting sound structures -- affecting the ability to map speech sounds onto letters.
However in Chinese dyslexia, disordered phonological processing may coexist with abnormal visuopatial processing.
In the study, published in Cell Biology, scans showed activation in a portion of the brain known to mediate visuospatial processing was weaker in those with dyslexia than in the normal readers. Those with the visuospatial problem also showed a phonological processing disorder as shown by their performance of a phonology-related rhyme judgment task.
"Written Chinese maps graphic forms -- characters -- onto meanings; Chinese characters possess a number of intricate strokes packed into a square configuration, and their pronunciations must be memorized by rote," the researchers said in a statement.
"This characteristic suggests that a fine-grained visuospatial analysis must be performed by the visual system in order to activate the characters' phonological and semantic information."