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Abstract:
Effects of lexical-semantic factors in working memory and
language comprehension have been shown in studies with normal and
brain-damaged subjects. In this study, we investigated
lexical-semantic integration deficits in sentence comprehension in
patients with Alzheimer's disease. A sentence anomaly judgment task
was presented auditorily to subjects. Stimuli included sensible and
anomalous sentences containing lists of one, two, or three
adjectives either preceding or following a noun. It was expected
that the prenominal condition would be more difficult than the
postnominal condition, as in the prenominal condition adjectives
must be held for subsequent integration with the noun in the
sentence, whereas in the postnominal condition, adjectives follow
the noun and immediate integration is possible. Results showed that
overall patients were less accurate than controls, and anomalous
were more difficult than sensible sentences for both groups.
Reaction time analyses for anomalous sentences indicated that
patients performed more poorly in the prenominal condition with
three adjectives. There was a nonsignificant trend in the same
direction for controls, and, for both groups, in the sensible
condition. This pattern was not found in the postnominal condition
for either patients or controls. These findings provide evidence
for effects of semantic retention in sentence comprehension. They
suggest that sentence comprehension impairments in Alzheimer's
patients may be related to a deficit in lexical-semantic
integration.
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