The indirect influence of prior experience on a subsequent task is termed
Implicit memory (IM). This study examined the status of pictorial and verbal IM
in four groups of 20 subjects each: normal young (M age = 27.2), young-old (M
age = 66.7), old-old (M age = 76.6), and Alzheimer's disease (AD) patients (M
age = 75.4, M Mini-Mental State Examination score = 17.3). Study conditions
involved reading words, naming pictures, and generating best-fit endings for
high-cloze sentence frames (e.g., Ron swept the floor with a ____ .). Implicit
memory was subsequently assessed by word-stem completion (WSC), in which
subjects were instructed to complete three-letter stems with the first word that
came to mind (e.g., bro____), and picture-fragment identification (PFI), in which
subjects attempted to identify perceptually degraded pictures. Among the
control groups, WSC priming was greatest following word study, and PFI
priming was greatest following picture study, thereby establishing that crossover
priming effects recently found among young subjects are fully retained in
healthy aging, In contrast to previous studies suggesting that WSC priming may
be preserved for deeply encoded material in AD patients, the present results
showed that WSC priming was impaired in the AD group regardless of study
condition, Nevertheless, AD patients demonstrated normal perceptual priming
on the PFI task following picture study, These findings support a dissociation
between perceptual and conceptual priming in AD. Explicit yes/no recognition
testing revealed standard picture superiority and generation effects among
controls. AD patients, in contrast, were impaired on all recognition items.
Results are discussed in terms of transfer-appropriate processing theory, which
states that level of retention Is a function of the degree to which processes
invoked at study are recapitulated at test. Essentially, the similarity between
word reading and WSC and between picture naming and PFI is a crucial
determinant of priming effects In healthy young and elderly subjects. AD
patients' WSC impairment may be due to a lexical-semantic processing deficit,
whereas their preserved PFI priming may be supported by intact perceptual
processes. Similarly, their uniformly depressed recognition memory may be
explained by impaired conceptual processing. / Graduate
| Identifer | oai:union.ndltd.org:uvic.ca/oai:dspace.library.uvic.ca:1828/9630 |
| Date | 06 July 2018 |
| Creators | Rich, Jill Bee |
| Contributors | Dixon, Roger A. |
| Source Sets | University of Victoria |
| Language | English, English |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf |
| Rights | Available to the World Wide Web |
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