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Abstract:
here is considerable evidence to suggest that semantic memory
is impaired early in the course of dementia of the Alzheimer-type
(DAT). The present study compared semantic memory in DAT patients
and healthy elderly control subjects. Four tests were employed
which involved mechanisms of either voluntary or automatic access
to information in semantic memory. Both on- and off-line tasks were
chosen to investigate whether reported deficits in semantic memory
in DAT result from a loss of stored information or simply from a
failure to access stored information. The tasks assessing voluntary
access included category fluency, within category word-picture
matching, and visual confrontation naming. The test of automatic
access was naming latency on a semantic priming test. Test stimuli
comprised category co-ordinates from both living and non-living
categories. The results showed that although DAT patients generated
fewer exemplars on the category fluency test compared to control
subjects, no category specific impairment was found. On the
word-picture matching task, DAT patients made few errors, whereas,
on picture naming, they made significantly more errors on living
items compared to non-living items. In contrast, however, DAT
patients only showed priming effects for living prime-target pairs.
The results are discussed in terms of the information loss versus
access failure hypotheses.
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