Pictorial memory in patients with right, left and diffuse brain damage

Abstract

Immediate and delayed recognition of realistic pictures were studied with a continuous recognition procedure in large groups of aphasics, non-aphasic left and right brain-damaged patients, normal controls and patients with a dementia of the Alzheimer type. The study aimed at clarifying the following points. (a) Is visual recognition of easy to label pictorial stimuli mainly impaired by aphasia, as the verbal loop hypothesis would predict, or is it related to a right hemisphere damage, as the dual code hypothesis would rather suggest? (b) Is the influence of the verbal code critical for short-term visual memory and the visual code relevant only for delayed recognition, or is the visual code important both for short-term and for long-term visual memory? (c) Are results obtained by patients with focal brain injury different from those obtained by Alzheimer's disease patients? Data obtained suggest the following answers. (a) A verbal description is not necessary to store in memory pictorial material for immediate or delayed recognition, since aphasic patients scored in both conditions significantly better than right brain-damaged patients, (b) The visual code seems equally important for both immediate and delayed recognition, since no change was observed in the accuracy score of aphasic patients passing from the immediate to the delayed condition, (c) Pictorial memory disorders are much more important in Alzheimer's disease patients than in subjects with focal brain injury. Alzheimer's disease patients scored, in fact, significantly worse than any other group of subjects with focal brain damage, both in immediate and in delayed visual recognition. Furthermore, the same patients showed a further significant decline in performance passing from the immediate to the delayed condition, whereas no change in the same direction was shown by the other brain-damaged groups.