Eye movement patterns in linguistic and non-linguistic tasks in developmental surface dyslexia

Ten subjects who could be reliably assessed as surface dyslexics were selec ted on the basis of a large test battery. Eye movements in non-linguistic a nd linguistic tasks were studied in these subjects. Stability of fixation on a stationary stimulus was examined. Performance of dyslexics was no different from that of an age matched control group. Simi larly, no difference was observed between the two groups when they were req uested to saccade to a rightward or leftward target. On the other hand, whi le reading short passages, dyslexics showed an altered pattern of eye movem ents with more frequent and smaller rightward saccades as well as longer fi xation times. The reading pattern was analysed by eye tracking. Numerous fi xations were used to read a single word in a fragmented way. Longer words s howed a higher number of fixations. Overall, it was concluded that surface dyslexia is not associated with ocul o-motor dysfunction and the study of eye movements in reading reveals the p rocessing through orthography-to-phonology conversion characteristic of sur face dyslexia. The importance is stressed of examining selected groups of s ubjects in the psychophysiological study of dyselxia. (C) 1999 Published by Elsevier Science Ltd. All rights reserved.