Journal Article

Lost in semantic space: a multi-modal, non-verbal assessment of feature knowledge in semantic dementia

Peter Garrard and Erin Carroll

in Brain

Published on behalf of The Guarantors of Brain

Volume 129, issue 5, pages 1152-1163
Published in print May 2006 | ISSN: 0006-8950
Published online April 2006 | e-ISSN: 1460-2156 | DOI: http://dx.doi.org/10.1093/brain/awl069
Lost in semantic space: a multi-modal, non-verbal assessment of feature knowledge in semantic dementia

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A novel, non-verbal test of semantic feature knowledge is introduced, enabling subordinate knowledge of four important concept attributes—colour, sound, environmental context and motion—to be individually probed. This methodology provides more specific information than existing non-verbal semantic tests about the status of attribute knowledge relating to individual concept representations. Performance on this test of a group of 12 patients with semantic dementia (10 male, mean age: 64.4 years) correlated strongly with their scores on more conventional tests of semantic memory, such as naming and word-to-picture matching. The test's overlapping structure, in which individual concepts were probed in two, three or all four modalities, provided evidence of performance consistency on individual items between feature conditions. Group and individual analyses revealed little evidence for differential performance across the four feature conditions, though sound and colour correlated most strongly, and motion least strongly, with other semantic tasks, and patients were less accurate on the motion features of living than non-living concepts (with no such conceptual domain differences in the other conditions). The results are discussed in the context of their implications for the place of semantic dementia within the classification of progressive aphasic syndromes, and for contemporary models of semantic representation and organization.

Keywords: connectionist modelling; motion; semantic dementia; semantic features; semantic memory; FRT = Feature Reality Test; CCP = Camel and Cactus Test

Journal Article.  7657 words.  Illustrated.

Subjects: Neurology ; Neuroscience

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