Lexical semantics and aphasia: A state-of-the-art review

Abstract

From a methodological point of view it is argued that “lexical semantics” should refer solely to grammatical constraints of lexical items. Knowledge-based approaches in linguistics as well as in cognitive psychology are inappropriate candidates for predicting meaning processes involved in lexical comprehension and production. Particular emphasis is given to the “semantic deficit hypothesis” which claims that, in particular, Wernicke's aphasics are impaired in processing lexical meanings. It is shown, however, that “semantic errors” in lexical production cannot necessarily be accounted for by semantic disorders. Moreover, results of several lexical similarity-judgement tasks, which have been interpreted to be indicative of a supramodel semantic deficit, can be better predicted by lexical access deficits along with “meta-cognitive” difficulties. Finally, the possibility is taken seriously that off-line research of lexical processes implies a methodological solipsism, that is, strategies which reflect “super-structures” of the examiner's mental model are tested and not structures of the language processing system. The status of lexical semantics according to issues of multiple lexical conceptual routes and modularity is discussed.