Reading disability: age differences and the perceptual-deficit hypothesis.

The present study assessed the suggestion that specific reading disability is caused by visual-spatial disorder. A previous investigation questioned this hypothesis in demonstrating that poor readers' orientation errors (e.g., b/d; was/saw) result from malfunction in verbal identification rather than optical distortion. However, the generality of its findings was limited by the fact that its subject included only children at the upper age levels (9-15 years). In order to extend our results to younger children, poor and normal readers in the second and sixth grades were presented with tachistoscopic exposures of both verbal and nonverbal stimuli and were asked to identify and/or reproduce them both orally and graphically. With some exceptions, the results obtained in the previous study were replicated: the performance of poor readers at both age levels closely approximated that of normals in visual as compared with verbal encoding.