Visual Figure-Ground Discrimination in Patients With Unilateral Cerebral Disease

Abstract

The purpose of this study was to evaluate the influence of aphasia, of visual field defects and the hemispheric side of the lesion on Gottschaldt Hidden Figure Test. This test was administered to 95 right handed patients with unilateral lesions of the cerebral hemispheres and to 40 control patients. The brain-damaged sample was divided into sub-groups according to the side of the lesion and the presence/absence of visual field defects and (within the left hemisphere group) of aphasia. Scores were compared by means of co-variance analyses, concomitant variables being age, years of schooling and visual reaction times (considered as a measure of the severity of the lesion). Il was found that visual field defects did not significantly affect the test scores. In contrast, poor performances were significantly associated with the presence and severity of aphasia. Right brain-damaged patients performed not differently from left brain-damaged patients, considered as one group. However, they did significantly worse than non-aphasic left brain-damaged patients. These were the only group whose mean score was virtually as good as that of the control group. These findings seem to indicate that poor visual figure ground discrimination (as tested by Gottschaldt test) in brain-damaged patients may be due to the impairment of at least two specific abilities, i.e. language (or some intellectual factor closely related to it) and some other ability (perhaps a visuo-spatial ability), preferentially subserved by the right hemisphere.