Differences in visuospatial judgement in reading-disabled and normal children.

Both visual and verbal impairments have been reported in two independent streams of research into the etiology of dyslexia or reading-disability. To address the question of the presence of either abnormality in reading-disabled children, visuospatial and phonological ability were assessed and contrasted in 39 Normal and 26 Reading-disabled children. To assess whether these deficits are unique to dyslexia, scores were also compared to those of a group of 12 Poor Readers ("garden-variety" backward readers with low IQs). The Benton Judgement of Line Orientation Test was used for its simplicity and clinical reliability: Reading-disabled subjects performed significantly worse than Normal readers (but similar to Poor Readers). Reading-disabled subjects performed worse for lines in the left-hemifield compared to Normal subjects and also had a greater tendency to scan the task in reverse order (left-to-right) from the usual right-to-left scanning pattern observed in the Normal group when performing this test. When both verbal and visuospatial variables were combined in a multiple regression analysis, 71% of reading variance could be accounted for. These results suggest that Reading-disabled children not only have poor phonological awareness, but they also show visuospatial deficits. However, poor performance on both these tasks was also observed in the group of Poor Readers, suggesting that these deficits are not unique to children with specific reading disability. The results lend further evidence to the hypothesis that reading disability cannot solely be attributed to left-hemisphere dysfunction resulting in phonological impairment. There are other behavioral deficits, possibly caused by a common mechanism, some of which, like visuospatial ability, can be measured by simple behavioral tests such as the Judgment of Line Orientation Test.