[Disorders of lateralization caused by severe organic brain damage]

The decisive period of the development of dominance is in the fourth year. Aphasic disturbances in younger children therefore have as their prerequisite bilateral lesions, it being only after this period that aphasias may be observed to be associated with unilateral cerebral lesions. Up to the fourth year of life it is, therefore, possible for unilateral cerebral lesions to be relatively easily compensated by a "change of dominance".