Constructional apraxia and visuoperceptive disabilities in relation to laterality of cerebral lesions.

The main purpose of the present study was to determine whether constructional apraxia is due to a visual perceptual disorder in right but not in left brain-damaged patients. In order to resolve this question, 36 normal controls and 73 brain-damaged patients with lesions restricted to the right (N = 30) or to the left (N = 43) cerebral hemisphere were given a graphomotor and a multiple choice version of the Benton Visual Retention Test. The graphomotor version of the V.R.T. was used as a test of constructional praxis, whereas the multiple choice version of the V.R.T. was used as a test of visual form discrimination. No difference was found between right and left brain-damaged patients with respect to incidence and severity of visuo-constructive and of visuo-perceptive disabilities. Contrary to the hypothesis, the relationship between perceptual and praxic tasks was higher in left than in right brain-damaged patients. The high level of correlation found between graphomotor and perceptual scores within the left hemispheric group was due chiefly to the poor performances obtained on both tasks by aphasic patients. These findings are interpreted as suggesting that the basis for visuoconstructive disturbances is a perceptual disorder, independently of the hemispheric side of lesion. The contrasting results of our intercorrelational study and of analogous studies reported in neuropsychological literature are interpreted as being due to sampling differences, in the absence of clearcut qualitative or quantitative differences between visuo-constructive disabilities of right and left brain-damaged patients.