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Abstract:
This study of word retrieval in aphasia used a sentence
completion task to investigate the functional locus of breakdown
leading to selective impairment of verb (relative to noun)
production among aphasic patients. Previous studies have produced
conflicting interpretations concerning whether such effects arise
at a level at which semantic and syntactic information is
specified, or at a later, form-based, stage of lexical processing.
Six aphasic stroke patients who produced nouns significantly better
than frequency-matched verbs in picture naming were tested on a
sentence completion task with high cloze probability for the
elicitation of 46 pairs of nouns and verbs matched for frequency
and imageability. The task was administered again approximately six
weeks later with a phonemic cue at the completion site. Three
patients showed a noun advantage in the uncued completion task, and
the difference was maintained as performance improved with cuing .
The other three patients showed no noun advantage in the uncued
completion task, as both noun and verb production was poor relative
to picture naming. However, these patients showed a significant
cuing effect for nouns only, resulting in the restoration of the
noun advantage with phonemic cuing. Results suggest a different
basis for selective verb impairment in the two subgroups,
supporting multiple sites for the representation of grammatical
information in the lexicon.
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