The nature of the phonemic string deficit in conduction aphasia

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Abstract
A case of conduction aphasia (CM) is presented to further explore the notion that such aphasics possess a phonological output disorder in constructing phonemic strings. Most studies on this topic have been restricted to the oral production of single words. This study sought to increase understanding of this phonological deficit by examining its interference with orthographic production and its manifestation in running speech. The latter was particularly important, because the diagnosis of a phonemic string deficit in conduction aphasia has been based on a model that was developed to explain segmental errors in normal running speech (cf. Shattuck-Hufnagel 1979). Results indicated that the phonemic string deficit in CM does interfere with orthographic processing, and that while both normal adults and CM exhibit disruption in constructing phonemic strings, the manner of breakdown, as characterized by Shattuck-Hufnagel, is different. The between-word errors of normal speakers typically involve the mislocation of word-initial consonants, an error pattern that has been attributed to a momentary disruption in ordering segments within phonemic strings (Shattuck-Hufnagel 1987). By contrast, the between-word errors of CM typically involved the perseveration of segments within the rhymes of syllables (or words). The distribution of these segmental errors is attributed to difficulty in clearing a phonemic output buffer.