Budson, A., Dafner, K., Desikan, R., Schacter, D.(2000). When False Memory Recognition is Opposed
by True Recognition: Gist-Based Memory Distortion In Alzheimer's Disease. Neuropsychology, 4, No.
2, 277-287.
Budson et al examined distortions in gist- based memory of Alzheimer's patients.
AD (Alzheimer's disease) patients have problems of memory distortion and retrieving desired
information. Past research has focused more on AD patients and their tendency to "produce unstudied
items or intrusions on memory tests." Balota et al. (1999) found that AD patients had a substantial
impairment in recalling studied words from the DRM paradigm and they were more likely than controls
to produce unrelated lures. However, there was no difference between AD patients and controls
producing related lures. A study done by Verafaellie et al. using the DRM paradigm found in initial
trials amnesic patients made less correct responses for studied items and less false alarms for related
lures than controls did. They also found that amnesic patients increased true recognition across trials,
and contrasting with the control (which over repeated trials increased true recognition and decreased
false recognition) did not show a decrease in false recognition across trials.
The current study "examined the semantic associates" of AD patients, older adults, and younger adults
by using a paradigm. False recognition rates were shown after a single and multiple trials to the word
lists.
METHOD
Twelve probable diagnosed AD patients, 12 older adults, and 12 healthy young adults
participated.
Participants. The Alzheimer's patients were at a mild or moderate stage with the disease.
All participants were presented a semantic associate list from Roediger and McDermott (1995)
study.
Half of the participants were presented list set A, the other half list set B. Each set contained six
15 word lists. The lists were presented one time per trial and five trials were given to each
participant.
Participants read the words presented on a computer screen aloud and were told to remember
them for a test that followed. Tests given contained presented words, critical lures (related lures)
and unrelated lures.
RESULTS
True Recognition
First Trial: AD patients made more "old" responses to unrelated lures than did older adults.
Analysis revealed a significant reduction in recognition accuracy for corrected recognition
(subtract proportion of "old" responses to unrelated lures from proportion of "old" responses to
studied words)
False Recognition
First Trial: AD patients showed a reduction in corrected false recognition (subtract the
proportion of "old' responses to unrelated lures from the proportion of "old" responses to related
lures) compared to old adults.
Young adults had decreases in false recognition levels across trials.
Older adults across trial levels fluctuated.
Signal Detection Analysis (SEE PAGE 281)
A' represents sensitivity. Ranges from 0- 1.
Bd" represents response bias. Ranges from -1 (liberal) to I (conservative).
Item Specific Recollection
Hits compared with unrelated false alarms
A' increases throughout trials. A' was higher in older adults than in AD patients
Bd" decreased for older and younger adults and stayed the same for AD patients.
Hits compared with related lure false alarms
A' increased for older and younger adults, but stayed at near chance levels for AD patients.
A significant effect between AD and older groups showed a significant effect of trial.
Bd" scores were low and became lower as the number of trials increased.
GIST MEMORY: Related lures false alarm compared with unrelated-lure false alarms
A' here is the tendency to rely on gist memory despite any influence from item-specific memory.
A' was lower in the first trial for AD patients compared to old adults.
A' didn't significantly rise over all trials, but did over trials 1-3 and a plateau was seen at trials
4&5.
A' didn't change over trials for old adults
A' decreased for young adults over trials.
Discussion
AD patients have less false recognition at the initial trial but over trials the false recognition
increases.
AD patients make false alarms to unrelated items more than older adults.
AD patients' false recognition to false alarms increase over trials.
AD patients use mostly memory from gist information. This accounts for increase in true
recognition of studied items and their inability to distinguish related lures from studied items.
The authors suggest this is due to frontal lobe dysfunction and wanted to note that AD patients
can learn the gist of information repeatedly presented to them.