Letter recognition ability of aphasic subjects.

This study examined the letter-recognition abilities of 44 aphasic and 10 normal subjects. On a 26-item letter recognition task normal subjects made no errors. Moderately aphasic subjects illustrated minimal difficulty but did not differ significantly in performance from normals. Severely aphasic subjects exhibited marked impairment and made significantly lower letter-recognition scores than moderate aphasic or normal subjects. Type of aphasia as determined by conversational speech fluency (fluent or nonfluent) seemed to affect the letter-recognition performance of the severely aphasic subjects. Fluent severely aphasic subjects made significantly lower scores than all groups; nonfluent severely aphasic subjects made significantly lower scores than all groups except the severe nonfluent group. The types of letter-recognition errors produced by the two severely aphasic groups offer some explanation as to their performance differences. Errors of the latter group were more likely to be related to the stimulus letter; errors from the former group tended to be random. Findings indicate the intactness of the aphasic subjects's semantic associational network is important to the letter-recognition process.