The impairment of verbal semantic memory: a single case study.

We report our investigations of a single patient in whom there was a selective impairment of semantic memory. She had a marked deficit of individual word comprehension although other language and linguistic skills were relatively preserved. Here we document that her failures in word comprehension were stable over a long time period. She made "phonological" errors in defining meanings, which we argue are analogous to "visual" errors in reading. On verbal learning tasks her performance was shown to be relatively preserved, a finding which provides evidence of the dissociation of verbal semantic memory and episodic (event) memory.