Repeating without semantics: Surface dysphasia?

We describe our investigations of MNA, who had a progressive, severe and gl obal loss of semantic knowledge (semantic dementia), Her verbal vocabulary was restricted to a few common words and she was also unable to recognize c ommon objects from sight, By contrast, she had a well-preserved digit span (7-8 digits). In this series of experiments, we focused on her ability to r epeat lists and sentences in which familiarity, meaningfulness, morphology and syntactic structure were manipulated. In list repetition tasks, we foun d that MNA showed a reliable effect of phonological similarity, word freque ncy and stimulus lexicality, but was unaffected by linguistic complexity, w ord length, semantic coherence or the status of individual stimuli as 'know n' or 'unknown'. In sentence repetition, her performance was not influenced by any semantic variables. However, there was a substantial effect of the frequency of the constituent vocabulary, even for words outside the range o f her retained vocabulary. The influence of syntax was restricted to minor effects of morphology, The phonemes of syllables and the syllables of words are bound by their co-occurrence rather than their meaning. We conclude th at the phonological representation of words is functionally independent of the semantic system.