Visual Memory for Colors in Patients with Unilateral Brain Damage

Abstract

The purpose of the present study was to examine systematically the performance of patients with unilateral hemispheric lesions (57 left hemisphere-damaged patients and 54 right hemispere-damaged patients) in order to ascertain which of these two factors, implicit verbal mediation and chromatic perceptual discrimination, play the greater role in the performance on two tests of short-term memory of colored patterns. The tests were built up in such a way that it was reasonable to assume that the performance on the first test could be aided by internal verbalization, and was very easy from the perceptual standpoint, while the performance on the second test could not be aided by internal verbalization, and was very demanding from the point of view of chromatic discrimination. The following two possibilities were anticipated: 1) if implicit verbal mediation represents an important mechanism in the short-term memory for colors, left brain-damaged patients should show poorer performances than right brain-damaged patients on the first test, but not on the second; 2) if, on the other hand, subtle perceptual chromatic discrimination represents an essential moment in the short-term memorization of colors, right brain-damaged patients should show worse performance than left brain-damaged patients on the second test. It was found that left brain-damaged patients performed more poorly than right brain-damaged patients on both tests. However, the performance on the memory tests was relatively independent of the performance on two oral language tests. It was concluded that the left hemisphere is more contributing than the right one to the performance on these mnestic tasks and it was suggested that this sub-dominance of the left hemispere cannot be identified with the dominance for language.