from: New study: eye movement problems in dyslexic children (October 28, 2012)
A large amount of data has shown that eye movements during reading are abnormal in dyslexia and this has been reported in different languages. Pavlidis  was the first to show a high number of regressive saccades and unstable fixation in dyslexic population; Rayner  reported frequent saccades of smaller amplitude as well as longer duration fixation in dyslexic children; similarly, De Luca et al.  observed frequent fixations with longer duration in Italian dyslexic children and Hutzler & Wimmer , also showed a high number of fixations and short duration in dyslexic children. Furthermore, in Chinese dyslexic children, Li et al.  reported abnormal eye movements in picture searching, slow and more fixations and frequent saccades of small amplitude.A large amount of data has shown that eye movements during reading are abnormal in dyslexia and this has been reported in different languages. Pavlidis  was the first to show a high number of regressive saccades and unstable fixation in dyslexic population; Rayner  reported frequent saccades of smaller amplitude as well as longer duration fixation in dyslexic children; similarly, De Luca et al.  observed frequent fixations with longer duration in Italian dyslexic children and Hutzler & Wimmer , also showed a high number of fixations and short duration in dyslexic children. Furthermore, in Chinese dyslexic children, Li et al.  reported abnormal eye movements in picture searching, slow and more fixations and frequent saccades of small amplitude.
Recently, Trauzettel-Klosinski et al.  reported in German dyslexic children slower reading speed and high number of saccades and regressions; similar findings have been also reported in Greek dyslexic children by Hatzidaki et al. . Taken together all these findings suggest that the abnormal eye movement performance observed in dyslexic children could be due to poor ability and strategy of visual information processing. Recently Jainta & Kapoula  reported in dyslexics poor binocular coordination of saccades during reading as well as in non reading task (while exploring a painting), while other studies on dyslexic children comparing reading and non reading tasks found ocular motor deficits in the reading task only ,.
The presence of a poor visual system in dyslexics has been suggested since many years  who first reported dysfunction at the level of the magnocellular system in dyslexics. Following this work, many studies confirmed this hypothesis showing in dyslexic children poor binocular coordination during prolonged fixations , visual confusion during reading  and poor eye alignment during fixation after the saccade . Iles et al.  also reported an impairment in visual search performance in a group of dyslexic adults with a motion coherence deficit confirming and extending the magnocellular hypothesis of dyslexia. Despite these results, recent research did not share the hypothesis of poor visual system, and the existence of a deficiency in the magnocellular system in dyslexia is still under debate , .
Furthermore, one should also mention that apart from the visual perceptual deficiencies, visual attentional processes are involved in reading and they could be responsible for altered eye movements’ performance in dyslexic population. In this line of thinking, Bosse et al.  reported that some dyslexic children have a reduced visual attentional window size leading to a limitation in the number of letters which can be processed in parallel. A consequence of such a disorder is that dyslexics will make shorter saccades and frequent fixations with respect to non dyslexic children not only during reading task but also during visual search . A recent fMRI study of this group  provided evidence on the role of parietal regions, particularly the left superior parietal area, in the visual attentional span and its deficiency in dyslexics.
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