Semantic, phonological, and hybrid veridical and false memories in healthy older adults and in individuals with dementia of the Alzheimer type

Five groups of participants (young, healthy old, healthy old-old, very mild dementia of the Alzheimer type [DAT], and mild DAT) studied 12-item lists of words that converged on a critical nonpresented word (cold) semantically (chill, frost, warm, ice), phonologically (code, told, fold, old), or in a hybrid list of both (chill, told, warm, old). The results indicate that (a) veridical recall decreased with age and dementia; (b) recall of the nonpresented items increased with age and remained fairly stable across dementia; and (c) false recall varied by list type, with hybrid lists producing superadditive effects. For hybrid lists, individuals with DAT were 3 times more likely to recall the critical nonpresented word than a studied word. When false memory was considered as a proportion of veridical memory, there was an increase in relative false memory as a function of age and dementia. Results are discussed in terms of age- and dementia-related changes in attention and memory.     

False memory and schizophrenia: evidence for gist memory impairment

BACKGROUND: In this study we examined patients' false memory, that is memory for a non-presented event, to search for a further source of converging evidence for the impairment of semantic memory in individuals with schizophrenia. In two experiments we compared the pattern of false memory created by the Deese-Roediger-McDermott (DRM) paradigm between individuals with schizophrenia and those of a normal control group. METHOD: Experiment 1 tested participants on both recall and recognition of lists of semantically related words. Experiment 2 adopted the meaning recognition test, in addition to the standard recognition test, to assess the participants' gist memory. RESULTS: Individuals with schizophrenia performed worse than normal controls on both recall and recognition of studied words. The schizophrenia patients had higher rates of false recall and false recognition for semantically unrelated words than did the normal controls, suggesting an abnormal pattern of semantic activation in the former group. More importantly, no differences were found between the two groups with regard to false recall and false recognition of semantically related words. When the participants were tested for meaning recognition, however, the schizophrenia patients gave fewer 'old' responses to non-studied semantically related words than did the control group, indicating an impaired gist memory in schizophrenia patients. CONCLUSIONS: When asked to consciously retrieve word lists, individuals with schizophrenia showed impairment not only in item-specific memory but also in gist memory. The pattern of results is consistent with the storage deficit view of semantic memory in schizophrenia.     

Development of semantic knowledge in children's associative false memory

In the Deese-Roediger-McDermott (DRM) procedure, false recall of a word that was not presented (the critical-lure) can be produced when participants study a list of associative words related to the critical-lure. Recently, some studies using the DRM procedure showed that young children did not produce false recall. The present study hypothesized that the children did not produce false recall in those studies because the lists of words did not reflect the children's associative knowledge. To test this possibility, the present study developed lists that reflect the associative knowledge of five-year-old children and examined false recall using the DRM procedure. The results showed that children falsely recalled the critical-lure after studying the lists that reflected the children's associative knowledge, while they did not recall the critical-lure after studying the lists that reflected adults' associative knowledge. The results indicate that children produce false recall when the lists of words reflect those children's associative knowledge. The present finding suggests that the structuring of semantic knowledge that mediates false recall of the critical-lure has developed five years of age.     

WHEN TRUE MEMORIES SUPPRESS FALSE MEMORIES: EFFECTS OF AGEING

After studying a list of words that are all associated to a nonpresented target word, people often falsely recall or recognise the nonpresented target. Previous studies have shown that such false memories are greatly reduced when study lists are presented and tested several times compared to a single study/test trial. We report that older adults, who are sometimes more susceptible to memory distortions than are young adults, failed to exhibit any reduction in false recall or false recognition after five study/test trials compared to a single trial. By contrast, younger adults showed robust suppression of false memories after five study/test trials compared to a single trial. These results are consistent with the idea that older adults rely on memory for the general features or gist of studied materials, but tend not to encode or to retrieve specific details of individual items.     

Impaired implicit memory for gist information in amnesia

In 2 experiments using a converging associates paradigm, the authors evaluated implicit memory for gist information in amnesic patients. In Experiment 1, participants saw multiple sets of associates, each converging on a nonpresented theme word, and were then tested using an implicit word stem completion test and an explicit cued recall test. Amnesic patients showed intact implicit and impaired explicit memory for studied words, but memory for nonpresented lures was impaired, regardless of retrieval instructions. To evaluate whether impaired implicit memory for lures was due to accelerated forgetting of gist information, short study lists were used in Experiment 2, each consisting of a single set of associates. Amnesics' implicit memory for lures was again impaired. These results point to an inability to encode robust gist representations as the cause of impaired gist memory in amnesia.     

FALSE RECALL AND FALSE RECOGNITION: AN EXAMINATION OF THE EFFECTS OF SELECTIVE AND COMBINED LESIONS TO THE MEDIAL TEMPORAL LOBE/DIENCEPHALON AND FRONTAL LOBE STRUCTURES

The present experiment examined the false recall and false recognition of nonstudied words that are preceded by a list of strong associates in patients with amnesia due to damage restricted to medial temporal lobe or diencephalic regions (MTL/D amnesics), in nonamnesic patients with damage restricted to the frontal lobes (FL nonamnesics), and in amnesic patients with damage to the frontal lobes in addition to medial temporal lobe damage (FL amnesics). We used the Deese/Roediger and McDermott paradigm (Deese, 1959; Roediger & McDermott, 1995) in which people frequently claim that nonstudied words appeared on a presented list. At immediate free recall, the results taken together showed that MTL/D amnesic patients and FL nonamnesic patients produced higher levels of false memory than did controls. At recognition both types of amnesic patients produced less false recognition than either frontal-lobe patients or controls. The results are consistent with the hypothesis that abnormally high levels of false memories are related to the following three conditions: (1) partial memory for the word lists, (2) the ability to extract the semantic gist of the list, and (3) a deficit in strategic monitoring processes.     

Hallucinations, negative symptoms, and response bias in a verbal recognition task in schizophrenia

Several studies have reported an association between hallucinations and tendency to make false alarms in acoustic signal detection tasks. Previous work on patients with schizophrenia has suggested that false recognitions and other types of memory error were positively associated with hallucinations and inversely associated with certain negative symptoms of withdrawal. In this study, 40 patients with schizophrenia were administered a word recognition task. Mixed lists of high- and low-frequency words were presented, then the target words had to be recognized among distractors in immediate and delayed recognition conditions. Hallucination scores were correlated with an increased bias toward false recognitions of nonpresented words. Affective flattening tended to be correlated with a reduced bias toward false recognitions. Anhedonia was significantly correlated with a reduced response bias. Hallucinations and anhedonia therefore presented an opposite association with the response bias. The influence of word frequency and delay on this association is discussed.     

True and false memories in adolescents with psychosis: Evidence for impaired recollection and familiarity

Introduction. Psychotic patients are impaired on recall and recognition of studied items (true memory) and typically make more false recall (intrusions) and false recognition than controls, reflecting greater susceptibility to false memory. The functional mechanisms underlying these deficits are poorly understood. The aim of this study was to examine recollection and familiarity in true and false memory in psychotic adolescents without long-term exposure to medication and repeated hospitalisations.

Methods. Seventeen adolescents with psychosis and 17 matched controls were tested on a DRM false memory paradigm combined with a remember (R)/know (K)/guess (G) procedure. Recall and recognition of targets (studied words), critical lures (associated words) and unrelated distractors were measured. Between-group comparisons were made using t-tests and mixed ANOVAs. Independent estimates for recollection and familiarity were also calculated.

Results. True memory was impaired in patients. Similar rates of false memory for critical lures were found in both groups. False memory for unrelated distractors was increased in patients. Contrary to controls, who attributed more R and K responses to targets than lures, patients attributed similar proportions of R and K responses to targets and lures. Furthermore, patients attributed more K responses than controls to all distractors.

Conclusions. These findings suggest a deficit in recollection- and familiarity-based memory in psychotic adolescents as well as reliance on preserved gist or meaning-based memory to support poor item-specific memory.     

FALSE MEMORIES AND SOURCE MONITORING

This article investigates the relation between misremembering and source judgments in both the misleading information paradigm and the false memory paradigm. A computational model, CHARM (Composite Holographic Associative Recall Model), is used to simulate source monitoring in both paradigms. Despite the fact that CHARM stores memories in a composite memory trace, it is shown that the model can account for source judgements, and can explain the discrepancy between the source judgement and the recognition data in the misleading information paradigm. It also can account for the basic phenomena of the false memory paradigm, wherein thematically related items induce a memory for a nonpresented but prototypical critical item. In two experiments linking these two research lines, we presented the critical item in a different list from that used to induce the false memory effect. Although the model predicted that the presentation of the critical item should increase the false memory effect, its presentation inhibited false memories instead-but only with particular word lists and in certain treatment combinations. It seems likely that the presence of the critical item in an alternate list allowed people to use an exclusionary rule to inhibit the false memories. Such a rule would be straightforward to implement in CHARM, and could allow the model to account for this false memory suppression effect.     

Aging and retrieval-induced forgetting of associatively structured lists

Research on retrieval-induced forgetting has shown that remembering can cause forgetting of related information. This study examined whether such forgetting occurred for associatively structured lists and if aging influenced such forgetting. We compared retrieval-induced forgetting during a free recall test by using Deese/Roediger-McDermott (DRM) lists with an associative structure as the stimulus. Two age groups of young and old adult participants were tested. The results indicated that both age groups showed the same degree of retrieval-induced forgetting of the lists. These results suggest that the association between items causes retrieval-induced forgetting and that the inhibitory function of the association in retrieval-induced forgetting does not decline with age.     

Effect of directed forgetting on false recognition: an examination of the activation-monitoring hypothesis

This study examined the influence of directed forgetting on false recognition. Participants studied one of two types of lists consisting of words related to a critical non-presented (CN) word: high or low semantic-associative-strength lists. Thirty-one participants were instructed to forget the Ist list before studying the 2nd list (forget group), another group of 30 participants were instructed to remember both lists (remember group). This was followed by a recognition test and Remember/Know judgments. For CN words, the forget group showed more false recognition than the remember group only for high semantic-associative-strength lists. Moreover, higher proportions of Remember judgments were observed than Know judgments in false recognition responses. These findings are discussed in terms of the activation-monitoring hypothesis of false memories.     

Stress-induced cortisol responses, sex differences, and false recollections in a DRM paradigm

The current studies investigated whether acute stress potentiates false recollections (so-called "false memories") in a Deese-Roediger-McDermott (DRM) paradigm, and whether sex differences modulate these effects. Participants were assigned to either a stress (trier social stress test) or a control group. Subsequently, they were subjected to DRM word lists and probed for recall and recognition. Results showed no differences between the stress and control group on measures of false recollections (Study 1; N=60). Even though correct recall was impaired by acute stress, there were no differences between high or low cortisol responders and controls on false recall or recognitions rates (Study 2; N=92). These results suggest that cortisol responses do not directly potentiate false recollections. Neither in Study 1 nor in Study 2 did we find any evidence that the effects of cortisol on false recollections are different in men and women, although there was an indication that independent of stress men produced more commission errors.     

Rehearsal strategy use in Alzheimer's disease

Memory strategy usage and awareness of memory performance are both crucial for memory rehabilitation. We explored Alzheimer's patients' ability to apply and control learning strategies and also their ability to predict the effect of these strategies on subsequent performance. In a rehearsal condition, participants were explicitly asked to overtly rehearse words and were given as long as they liked at study. In a control condition, participants read the words passively at a fixed presentation rate. In all groups, recall was superior in the rehearsal condition than in the reading condition. Alzheimer's patients showed different strategy usage. Overall, people with Alzheimer's disease spend longer studying to-be-remembered words under unpaced conditions, but they do not use this time to rehearse to the same extent as controls. We hypothesize that this failure to rehearse could be based on the inability to use effortful executive mechanisms involved during study.     

MEMORY CONJUNCTION ERRORS IN YOUNGER AND OLDER ADULTS: EVENT-RELATED POTENTIAL AND NEUROPSYCHOLOGICAL DATA

In a study/recognition paradigm, new words at test were recombinations of studied syllables (e.g. BARLEY from BARTER and VALLEY), shared one syllable with studied words, or were completely new. False alarm rates followed the gradient of similarity with studied items. Event-related potentials to the three classes of false alarms were indistinguishable. False alarms elicited different brain activity than did hits, arguing against the idea that conjunction errors occur during encoding and are later retrieved liked genuine memories. In Experiment 2, with healthy older adults, neuropsychological tests sensitive to frontal lobe function predicted false alarm rate, but not hit rate. Performance on standardised memory scales sensitive to medial temporal/diencephalic function influenced the pattern of false alarm rates across the three classes of new words. The experiments suggest that false alarms to conjunction lures are not similar to true recollections, but are products of faulty monitoring at retrieval.     

The effect of encoding on false memory: examination on levels of processing and list presentation format

Using the Deese/Roediger-McDermott paradigm, the effects of lists presentation format (blocked/random) and levels of processing of critical nonpresented lures were examined. A levels-of-processing effect in a blocked presentation order was not observed for lures. Rates of false recognition and remember judgments for lures in a shallow level of processing were significantly lower than those in a deep level of processing when items from various themes were inter-mixed instead of blocked. Results showed an interaction between levels of processing and list presentation format. It is thus concluded that encoding of each word and whole list should be both considered in understanding false memory.     

预警提示、呈现时间对不同年龄错误记忆的影响

目的研究预警提示、呈现时间和年龄对错误回忆的影响。方法本实验采用DRM范式和听觉一视觉通道模式,选取年龄、呈现时间和预警提示3个因素,以平均年龄分别为11岁和19岁的少年和青年为被试,通过对预警提示与呈现时间的同时操纵进行研究。结果①呈现时间的主效应显著(F=39.296,P<0.001),年龄(F=3.258,P>0.05)和有无预警提示(F=0.154,P>0.05)的主效应不显著;②年龄与呈现时间的交互作用显著(F=8.947,P<0.001),呈现时间与有无预警提示的交互作用显著(F=6.033,P<0.05)。结论①在较长的呈现时间下,错误回忆会随着呈现时间的延长而降低;②在给予预警提示和延长呈现时间下,青年比少年产生较高水平的拒绝错误记忆;③在一般情况下,DRM范式下青年更容易产生错误回忆,他们也更能够拒绝错误记忆。     

Test-item sequence affects false memory formation: an event-related potential study

False memories arise when people 'remember' experiences that have never occurred. Using the Deese-Roediger-McDermott (DRM) paradigm, researchers have demonstrated that participants tend to falsely recognize non-studied words (lures) that are associated to previously studied words. Several questions, however, remain regarding the neurocognitive basis of false memory formation. Various encoding manipulations have been shown to affect the behavioral and electrophysiological correlates of false memories, but little is known about whether false memory formation and its neurophysiological correlates are influenced by different test contexts. We recorded event-related potentials (ERPs) during the DRM paradigm, wherein the test included lures that were either preceded by semantically related words or not. Results indicated more false recognitions for lures preceded by related words than for lures that were not preceded by related words at test. Furthermore, the former elicited more positive parietal potentials at 300-600 ms relative to the latter. These findings suggest that test context critically affects behavioral and neurophysiological responses for false memory, providing further insight into the neurocognitive basis of human memory.     

The differences in young and elderly adults on false memory: examination on the effect of retention interval

False recognition can occur at high levels after participants study lists of associated words and are tested with semantically related lures. The present study attempted to determine the differences of young and elderly adults in retention interval on false recognition and remember-know judgments of critical lure. Young participants' mean age was 21.6 years (range 21-23 years). Elderly participants' mean age was 69.7 years (range 65-74 years). Participants engaged in estimating the frequency of usage of visually presented words, and they were tested both immediately and one week later after the study phase. We found that elderly adults were relatively more susceptible than young adults to this false recognition effect. Moreover, a reliable increase of false recognition for critical lures was observed across retention interval in young adults but not in elderly adults.     

RBANS analysis of verbal memory in multiple sclerosis.

Patients with neurodegenerative diseases that cause mainly subcortical pathology often exhibit impairment when required to recall lists of unrelated words, but their memories are supposedly improved by test procedures that promote retrieval such as recognition or improve the organization of the to-be-remembered materials. Difficulties with floor effects on free recall and ceiling effects on recognition and other methodological concerns raise doubts about the validity of existing studies that tested these ideas. Using the verbal memory subtests of the RBANS, we [Arch. Clin. Neuropsychol. 18 (2003) 509] expressed each patient's performances on Story Memory, List Learning, Story Recall, List Recall, and List Recognition as Z scores relative to his or her age group. Then, the Z scores were subtracted pairwise to test hypotheses about the nature of memory in Parkinson's disease (PD). Contrary to expectation, patients with PD did not show better immediate or delayed recall of stories relative to lists and they did not show better recognition than recall. In the present investigation, the same methodology was used to study verbal memory in multiple sclerosis, a disease that primarily affects subcortical structures. In contrast to previous results for patients with PD, the patients with MS exhibited better recall of stories than of lists and better List Recognition than Recall. Differences in the pathology of entorhinal regions in PD and MS may contribute to the differing patterns of memory impairment of these patients. The results emphasize that most patients with MS with memory impairments have deficits that are relatively mild and potentially remediable.     

Rey Auditory-Verbal Learning Test: the effects of age and gender, and norms for delayed recall and story recognition trials.

Immediate recall and three measures of delayed memory performance were evaluated in 134 healthy adults aged 16-76. Gender of subjects had no Influence on performance for any of the acquisition or retention trials. Age influenced acquisition as memory load began to exceed five to six words, with older subjects exhibiting decreased capacity. There was little loss of information between the immediate and delayed recall trials for any age group. Norms for a 30-min delayed recall trial, commission errors on delayed recall, and delayed recognition using Rey's story recognition procedure are presented, and implications for clinical use are discussed.