The repetition defect in conduction aphasia: Mnestic or linguistic?

Repetition difficulty is the cardinal feature of conduction aphasia. Traditionally this disorder has been considered secondary to a deficit in linguistic processing but recently a number of investigators have interpreted such cases as consequent upon a short-term memory difficulty in the auditory—verbal domain. We present here the case of a 24-year-old patient with conduction aphasia, whose symptom picture closely resembles those patients whose difficulties have been attributed to mnestic factors. Our patient's performance improved dramatically when stimuli were presented more slowly or when they were familiar, when the task involved matching rather than language production, and when multiple choices were provided for missed items. More crucially the patient's errors in repetition were primarily paraphasic and sequential; and repetition of single nonsense words was severely impaired. Taken together these results suggest that the patient's disorder, and perhaps that of other cases as well, would be better viewed as a linguistic deficit, specifically in the processing, synthesis, and ordering of phonemes. A tentative model for repetition disorder is proposed.