The Influence of Aphasia and of the Hemispheric Side of the Cerebral Lesion on Abstract Thinking

Abstract

A modified version of Weigl Sorting Test which allows 5 criteria of classification was administered to 40 control patients, 40 right brain-damaged patients, 22 left non-aphasic brain-damaged patients and 45 aphasics. The performance of the 4 experimental groups was analyzed by means of co-variance analysis, independent variables being age, years of schooling and RT. Right and left non-aphasic brain-damaged patients performed not differently from control patients on Weigl test, while the mean score of the aphasic group turned out to be about one half of that of the control group. The analysis yielded the same results also when the score obtained by the patients on a general intelligence test (Raven's P. M. 1938) was introduced as an additional independent variable. The score obtained by aphasics on Weigl test was found to correlate highly with an auditory verbal comprehension score, while no significant correlation was found between Weigl score and either a visual naming or an ideomotor apraxia score. Patients with typical “amnesic” aphasia were not found to perform the test more poorly than patients with typical Wernicke's or Broca's aphasia. In conclusion, these data indicate that Weigl test is not sensitive to the presence of cerebral damage per se while it is highly sensitive to the presence of left (dominant) hemisphere lesions associated with aphasia. The evidence pointing to a specific defect of “abstract thinking” in aphasics may be interpreted as the consequence of a disruption of “inner language” in these patients; however, an alternative view may be advanced, viz., that the same areas subserving linguistic activities in the left hemisphere are also specialized in carrying out intellectual tasks of a symbolic nature.