Accessing semantic knowledge in dementia: Evidence from a word definition task

Arlene J. Astell*, Trevor A. Harley

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

16 Citations (Scopus)


We examine production of word definitions by people with probable Alzheimer's disease (pAD). In the first experiment, healthy young adults defined concrete, imageable nouns to provide a baseline of definitional ability. Analysis of these definitions identified the key defining features of each target item. In the second experiment, pAD participants and elderly controls produced definitions of the same items. In the third experiment, healthy young participants rated the adequacies of these definitions. Although as expected the pAD participants produced fewer good definitions than the other two groups, most of their responses still contained some relevant information. pAD definitions contained fewer pieces of information and the information they produced was more tangential to the primary concept than that provided by the young or elderly participants. We identify two possible explanations in semantic loss and metalinguistic impairment. We consider metalinguistic impairment to provide the more plausible explanation of pAD patients' definitional performance.

Original languageEnglish
Pages (from-to)312-326
Number of pages15
JournalBrain and Language
Issue number3
Early online date1 Aug 2002
Publication statusPublished - 1 Sept 2002
Externally publishedYes

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