| |
Abstract:
Previous research suggests that Alzheimers disease (AD)
patients exhibit deficits on conceptual implicit memory tests.
However, many of these studies have used tasks that require lexical
retrieval, a process known to be disrupted by AD. Thus, it is
difficult to determine whether the observed memory deficits reflect
disruption of conceptual implicit memory processes or processes
involving lexical access. The current study compared conceptual
implicit memory in AD patients to aged-matched control
participants, using a task that required a lexical search (category
exemplar generation) and two tasks that did not (semantic decision
tasks). For the decision tasks, reaction times were recorded as
participants made "yes/no" decisions regarding the size and shape
of objects. One experiment examined the facilitation in semantic
processing as a result of making the same semantic decision
compared to a condition in which a different semantic decision was
made at study and test. The second experiment examined the transfer
of priming effects across stimulus format (words and pictures). AD
patients showed a deficit on the conceptual implicit memory task
that required lexical retrieval. In contrast, they showed
equal-to-normal facilitation on the two semantic decision tasks.
These findings are important in characterizing the memory deficits
of AD relative to other memory-disordered groups, and in
determining the neural structures supporting conceptual implicit
memory.
|
