This study investigated two classifications of semantic features, feature importance and feature relevance, to verify if they differentially influence lexical semantic knowledge in individuals with aphasia. Feature importance is defined as "how important a feature is in defining a concept" (Hampton,1979), while feature relevance represents the "core meaning of a concept" (Sartori, Lombardi & Mattiuzi, 2005).
A sorting task was used with 20 volunteer participants with aphasia to investigate the semantic processing involved in the association of semantic features with nouns. A corpus of 18 nouns was displayed in front of each participant in groups of three along with a card containing the word "UNRELATED." The participants were given a deck of 18 cards containing features corresponding to the nouns and to the unrelated category, and were verbally instructed to sort the deck of cards into each of the four designated piles. The semantic features on the cards were rated as high, mid and low importance (HI, MI, LI) and high, mid and low relevance (HR, MR, LR).
Analysis was completed using a two-way between-subjects ANOVA to determine was whether the mean scores at the three different levels (e.g., low, mid and high) of importance and relevance differed, and to analyze if there was an interaction between the two classifications. The participants were able to assign high importance features with nouns more accurately than they did mid and low importance features. Feature relevance did not differentially influence noun-feature association. These results indicated that the ability of individuals with aphasia to accurately associate features with nouns is influenced by levels of feature importance.
In conclusion, this study found that individuals with aphasia are more cognitively sensitive to high level versus low level feature importance and the effect does not extend to a mid level of importance. The study also demonstrated that the levels of feature relevance did not differentially influence the ability of individuals with aphasia to associate semantic features with their appropriate nouns. Potential clinical implications and study limitations were discussed.
|School:||Kent State University|
|School Location:||United States -- Ohio|
|Source:||DAI-B 75/08(E), Dissertation Abstracts International|
|Subjects:||Neurosciences, Speech therapy|
|Keywords:||Aphasia, Lexical semantic knowledge, Semantic feature, Semantic memory|
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