The occurrence of visual neglect in patients with unilateral cerebral disease.

Visual neglect for the contralateral space has been reported to occur more frequently and more severely following right than left brain damage. The present study sought to determine whether this hemispheric difference is task dependent, i.e. is maximal for tests demanding a thorough exploration and minimal for tests leaving space scanning to the patient's initiative. The findings supported this hypothesis. When the occurrence of neglect was assessed by means of a copying drawings test omissions of details contralateral to the involved hemisphere were found only in the right brain-damaged patient. When the patient was required to bisect a line or to choose the correct response among the alternatives of the Raven test, a tendency for preferring the homolateral hemi-space was also shown by left brain-damaged patients, although it was much more marked in the right-sided group. When patients were asked to insert balls in the holes of a board, both hemispheric groups showed a preference for the homolateral space. The incidence of constructional apraxia was evaluation in the same hemispheric groups and found not to be significantly different.