fe'Sffi Lateral Dominance and Reading Disability

Theory and research on the relation of lateral dominance to the causation of reading disability is reviewed. Direct measures of cerebral hemisphere functioning indicate that the left hemisphere is dominant for speech, sequential processing, and logical thinking in nearly all right-handers and the majority of left-handers, while the right hemisphere is dominant for holistic or Gestalt perception, nonverbal reasoning, and music. However, the electro-encephalograph, which is the only direct indicator of cerebral dominance that does not require surgery, does not differentiate well between disabled and normal readers. Indirect measures include measures of handedness, directionality, dichotic listening, and tachisto-scopic presentation of visual stimuli to visual half-fields. Research on the relation of such measures to reading disability is reviewed. L ateral dominance means the preferred use and better performance of one side of the body as compared to the other side (Harris 1958). For this paper the meaning of the term will be expanded to include all aspects of laterality or sidedness, including motor functions, perceptual functions, and especially the unequal or asymme-trical functioning of the two cerebral hemi-spheres of the brain. Although the writers of some recent books on reading disability have questioned the signifi-cance of lateral dominance for reading (Spach