Different basic components in the performance of Broca's and Wernicke's aphasics on the Colour-Figure Matching Test.

It is known that focal damage of the left hemisphere causes poor performances in a number of tasks devoid of overt verbal connotation, often referred to as "non-verbal intelligence", "association" or "abstract attitude" tasks. However, it is not clear whether the existence of a unitary basic functional defect to account for the faulty performances outlined above can be supposed. In this investigation we have compared the behaviour of left-hemisphere damaged patients grouped according to aphasia type and have studied the extent to which two different, widely used tests of this supposed "non-verbal basic ability" (i.e. the Weigl Sorting Test and the Raven Progressive Matrices) overlap in their predictive power of the performance of a non-verbal association task, i.e. the Colour-Figure Matching Test. Notwithstanding the identical level of performance in the three tests between groups having different aphasia types, a clear-cut dissociation was found between Broca's and Wernicke's aphasics; in the former group the Colour-Figure Matching Test was highly correlated only with Weigl Sorting Test and in the latter only with Progressive Matrices. The conclusions are that in this case the breakdown of non-verbal basic resources does not coincide in patients with different types of aphasia, and the hypothesis of the existence of a unitary basic defect caused by left hemisphere damage is not in line with our findings.