The Comparative Efficiency of Intelligence and Vigilance Tests in Detecting Hemispheric Cerebral Damage

It is suggested as a further hypothesis that the performance on Raven's Matrices of right-sided patients, who have the more severe lesions, not worse than that of left brain-damaged patients, may be due to the fact that the left hemisphere is crucial for all intellectual tasks, verbal as well as non-verbal.

Abstract

The application of vigilance tests to cases of focal lesions has been investigated in brain-damaged (N: 166) and control patients (N: 139). The performances of the subjects on an intelligence test (Raven's Matrices, 1938) and in two vigilance tests (Visual Reaction Time and Continuous Choice Reaction) were compared. The two vigilance test showed greater efficiency in discriminating between normal and pathological subjects than the intelligence test, if the education level was not taken into account; this difference disappeared when specific criteria of discrimination, based on the years of schooling, were applied. The discrepancy between number of subjects classified correctly and incorrectly with the single and the specific threshold methods was greater with the Matrices than with the vigilance tests. The latter two tests do no differ from each other. In the comparison of aphasic versus left non-aphasic and left-sided versus right-sided patients there were no differences in the performances on Raven's Matrices. In the Continuous Choice Reaction the aphasics showed a poorer performance than the left non-aphasic, presumably because of the importance of internal verbalization for performance on this test; no difference was found between the two hemispheric groups. In Reaction Time aphasic and left non-aphasic subjects showed similar perfomances, but the right-sided patients were markedly slower than the left-sided ones. This result was interpreted tentatively as reflecting the presence of a more severe degree of cerebral damage in the right-sided group. The hypothesis is advanced that R.T. may be regarded as a measure of the severity of a lesion, unbiassed by its localization. This hypothesis raises the problem "why is the performance on Raven's Matrices of right-sided patients, who have the more severe lesions, not worse than that of left brain-damaged patients?" It is suggested as a further hypothesis that this may be due to the fact that the left hemisphere is crucial for all intellectual tasks, verbal as well as non-verbal.