Direction of spatial error in the copying of visual stimuli: the relevance of focal brain damage.

Hemisphere-damaged patients and control subjects were tested by copying visual stimuli from a large display. The vertical and horizontal components of the errors and the overall accuracy were analysed with the following results: (i) all the subjects displaced downward in the left half of the display and upward in the right half, except for the left hemisphere-damaged patients with visual field defect, (ii) both left and right hemisphere-damaged patients with visual field defect displaced the copied point toward the damaged hemisphere, and generally were inaccurate only in the half of the copying set opposite to the damage hemisphere, without asymmetry between the effect of left and right posterior lesion except for the presence of unilateral neglect only among subjects with right hemisphere lesions.