To investigate the ability of aphasics to retain verbal and nonverbal materials four memory tasks were administered to 28 patients with Broca's and Wernicke's aphasia, and 10 normal subjects. The verbal materials, presented visually and orally, were selected from the common objects. The namable set consisted of the objects the aphasic patients could easily name, while the unnamable set consisted of the objects they failed to name. The nonverbal materials were visually presented random shapes.
The major findings were the following
1) Although the retention span of the verbal materials in the aphasic patients was significantly smaller than that in the normal subjects, no significant group difference was found in the nonverbal materials.
2) In the patients with Wernicke's aphasia the pointing span of the namable objects was superior to that of the unnamable objects, when they were presented orally.
3) An inspection of correlation coefficients between the memory tasks revealed that the normal subjects tend to whereas the aphasic patients tend to retain them in terms of multiple codes, i.e., acoustic, visual and semantic codes.
The underlying mechanisms of aphasics retention deficiency specific to the verbal materials were discussed.
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