Mental rotation and visual laterality in normal and reading disabled children.

Normal and reading disabled children, aged from 11 to 13 years and matched for I.Q., were timed as they discriminated bs from ds. When the letters were presented only in their normal upright orientations, normal readers responded more quickly when they were presented in the right than in the left visual hemifield, while the disabled readers showed a slight but insignificant left hemifield advantage. When the letters were presented in varying angular orientations the reaction times indicated that both groups "mentally rotated" an internal representation of each letter to the upright in order to discriminate them. The two groups did not differ in the accuracy of discrimination or in the estimated rate of mental rotation, and there were no significant hemifield differences in this phase of the experiment. These data offer no support for the view that disabled readers are deficient in spatial ability, but confirm earlier evidence that they may suffer a lack of left-hemispheric specialization.