Source Memory Deficits Research Articles

Strategic retrieval, confabulations, and delusions: Theory and data

Based on Moscovitch and Winocur's “working with memory” framework, confabulation is described as a deficit in strategic retrieval processes. The present paper suggests that only a confluence of deficits on multiple memory-related processes leads to confabulation. These are divided into three categories. Core processes that are unique to confabulation and required for its evolution include: (1) an intuitive, rapid, preconscious “feeling of rightness” monitoring, (2) an elaborate conscious “editor” monitoring, and (3) control processes that mediate the decision whether to act upon a retrieved memory. The second category is deficits on constitutional processes which are required for confabulation to occur but are not unique to it. These include the formation of erroneous memory representation, (temporal) context confusion, and deficits in retrieval cue generation. Finally, associated Features of confabulations determine the content “flavour” and frequency of confabulation but are not required for their evolution. Some associated features are magnification of normal reconstructive memory processes such as reliance on generic/schematic representations, and positivity biases in memory, whereas others are abnormal such as perseveration or source memory deficits. Data on deficits in core processes in confabulation are presented. Next, the apparent correspondences between confabulation and delusion are discussed. Considering confabulation within a strategic memory framework may help elucidate both the commonalities and differences between the two symptoms. Delusions are affected by a convergence of abnormal perception and encoding of information, associated with aberrant cognitive schema structure and disordered belief monitoring. Whereas confabulation is primarily a disorder of retrieval, mnemonic aspects of delusions can be described as primarily a disorder of input and integration of information. It is suggested that delusions might share some of the associated features of confabulation but not its core and constitutional processes. Preliminary data in support of this view are presented.

HIV-Associated Episodic Memory Impairment: Evidence of a Possible Differential Deficit in Source Memory for Complex Visual Stimuli

HIV-Associated Episodic Memory Impairment: Evidence of a Possible Differential Deficit in Source Memory for Complex Visual Stimuli

Confabulation behavior and false memories in Korsakoff's syndrome: Role of source memory and executive functioning

Confabulation behavior is common in patients with Korsakoff's syndrome. A distinction can be made between spontaneous and provoked confabulations, which may have different underlying cognitive mechanisms. Provoked confabulations may be related to intrusions on memory tests, whereas spontaneous confabulations may be due to executive dysfunction or a source memory deficit. In 19 chronic Korsakoff patients, spontaneous confabulations were quantified by third-party rating (Likert scale). Provoked confabulations were assessed using the Dalla Barba Confabulation Battery. Furthermore, assessment of executive function was performed using an extensive neuropsychological battery. False memories (i.e. intrusions) and source memory were measured using twoparallelversions of a word-list learning paradigm (a modification of the Rey Auditory Verbal Learning Test). There were deficits in source memory, in which patients incorrectly assigned previously learned words to an incorrect word list. Also, Korsakoff patients had extensive executive deficits, but no relationship between the severity of these deficits and the severity of confabulation or intrusions on a memory task was found. The present findings provide evidence for a dissociation between spontaneous confabulation, provoked confabulation and false memories.

Fonctionnement de la mémoire chez les sujets avec autisme

Autism is an early developmental disorder with cognitive impairments that leads to learning and social integration disabilities. The characterization of memory functions in individuals with autism has been the subject of numerous investigations, with widely varying conclusions. The notable differences between these studies can be attributed to variations in the age, intelligence and level of severity of the participants with autism.The purpose of our review of the recent literature is to describe the memory function of individuals with autism. Some of the different memory subtypes are intact, others are impaired. Short-term memory (digit span) is not impaired while working memory is impaired in some of its components, but the findings are inconsistent. More recent studies demonstrate reduced spatial working memory abilities in autism and extend previous findings by demonstrating that these deficits are significant when tasks impose heavier demands on working memory. Episodic long-term memory, as measured by free recall, cued recall or recognition tasks, is intact, but participants with autism perform significantly less well than controls as the complexity of the verbal or visual material to be recalled increases. Source or contextual memory involves a variety of characteristics specifying the conditions under which specific items or facts are acquired: it has been investigated in individuals with autism with different methods. Deficits in source memory for temporal information have been found, but there were no reality monitoring deficits. Recent findings indicate that the nature of source memory confusion in autism does not appear to reflect a generalized deficit in attaching context to memories, but rather is dependant on the specific to-be-remembered information that involves social aspects of context. The self-reference effect is missing, with individuals with autism recalling events performed by themselves less well than the events performed by a peer, suggesting they have difficulties in relation to processes involving the self. Studies involving assessment of subjective states of awareness during recognition show less conscious recollection and more feelings of familiarity. Recent investigations are consistent in demonstrating memory impairments related to the failure of subjects with autism to use organizing strategies or meaning to support memory, an effect which grows with the increasing complexity of the material. Memory deficits in autism may be related more to retrieval and less to encoding, as deficit in source memory in participants with autism is largely eliminated when source was supported at test.The neuroanatomical basis of the specificities of memory impairment in autism is still uncertain, but it is suggested that autism involves an impairment in the conversion of limbic inputs into medial prefrontal outputs. Memory deficits found in individuals with autism may explain some of the clinical symptoms. Failure to encode all the information, especially its social aspects, may therefore contribute to dysfunction in the social, communication, and reasoning domains. Abnormal memory functioning in autism is also related to more general cognitive impairments, including executive function deficits and central coherence weakness. Evidence of the normality of certain memory capacities, at least in individuals with moderate autistic symptomatology, is encouraging for adaptive improvements in cognitive functioning.

Effects of aging on the neural correlates of successful item and source memory encoding.

To investigate the neural basis of age-related source memory (SM) deficits, young and older adults were scanned with fMRI while encoding faces, scenes, and face-scene pairs. Successful encoding activity was identified by comparing encoding activity for subsequently remembered versus forgotten items or pairs. Age deficits in successful encoding activity in hippocampal and prefrontal regions were more pronounced for SM (pairs) as compared with item memory (faces and scenes). Age-related reductions were also found in regions specialized in processing faces (fusiform face area) and scenes (parahippocampal place area), but these reductions were similar for item and SM. Functional connectivity between the hippocampus and the rest of the brain was also affected by aging; whereas connections with posterior cortices were weaker in older adults, connections with anterior cortices, including prefrontal regions, were stronger in older adults. Taken together, the results provide a link between SM deficits in older adults and reduced recruitment of hippocampal and prefrontal regions during encoding. The functional connectivity findings are consistent with a posterior-anterior shift with aging previously reported in several cognitive domains and linked to functional compensation.

False memory in aging: Effects of emotional valence on word recognition accuracy.

Memory is susceptible to distortions. Valence and increasing age are variables known to affect memory accuracy and may increase false alarm production. Interaction between these variables and their impact on false memory was investigated in 36 young (18-28 years) and 36 older (61-83 years) healthy adults. At study, participants viewed lists of neutral words orthographically related to negative, neutral, or positive critical lures (not presented). Memory for these words was subsequently tested with a remember-know procedure. At test, items included the words seen at study and their associated critical lures, as well as sets of orthographically related neutral words not seen at study and their associated unstudied lures. Positive valence was shown to have two opposite effects on older adults' discrimination of the lures: It improved correct rejection of unstudied lures but increased false memory for critical lures (i.e., lures associated with words studied previously). Thus, increased salience triggered by positive valence may disrupt memory accuracy in older adults when discriminating among similar events. These findings likely reflect a source memory deficit due to decreased efficiency in cognitive control processes with aging.

Source Memory, Aging and Culture

Background: The present study investigates the possibility that culture affects age differences in context memory. There is evidence that East-Asians process scenes more holistically and show better context memory than Americans. Objective: We examined evidence for differences in binding source to context in young and old Americans and native Chinese. We hypothesized that age effects on source memory could be mitigated due to these cultural differences in processing style. Methods: During incidental encoding, younger and older Chinese and Americans watched a video with statements spoken by four distinct speakers. After a brief interval, participants identified source (experiment 1) or item and source (experiment 2). Results: We observed substantial age-related deficits in source memory in both cultures but little evidence for cultural differences in source or item memory. Conclusion: Basic source memory processes operate similarly across culture and age. The source of holistic processing differences observed between cultures may occur in cognitive operations that are more highly bound to a social context.

Source memory retrieval is affected by aging and prefrontal lesions: Behavioral and ERP evidence

Age-related deficits in source memory have been attributed to alterations in prefrontal cortex (PFC) function, but little is known about the neural basis of such changes. The present study examined the time course of item and source memory retrieval by recording event-related potentials (ERPs) in patients with focal lesions in lateral PFC and in healthy older and young controls. Both normal aging and PFC lesions were associated with decrements in item and source memory. However, older controls showed a decrease in item hit rate with no change in false alarms, whereas patients showed the opposite pattern. Furthermore, ERPs revealed notable differences between the groups. The early positive-going old/new effect was prominent in the young but reduced in patients and older adults, who did not differ from each other. In contrast, older adults displayed a prominent left frontal negativity (600–1200 ms) not observed in the young. This left frontal effect was substantially smaller and delayed in the patients. The current results provide novel insights into the effects of aging on source memory and the role of the lateral PFC in these processes. Older controls appeared to adopt alternate memory strategies and to recruit compensatory mechanisms in left PFC to support task performance. In contrast, the lateral frontal patients were unable to use these mechanisms, thus exhibiting difficulties with strategic memory and monitoring processes.

An fMRI investigation of short-term source memory in young and older adults

Using functional magnetic resonance imaging (fMRI) and a working memory procedure, we compared source memory judgments (format and location) with old–new judgments in young and older adults. Consistent with previous fMRI findings, for young adults, an area of left dorsolateral prefrontal cortex showed greater activity during format than old–new judgments made immediately, as well as those made after a brief, filled delay. In contrast, for older adults, activity in this area was not greater during format than old–new judgments at either retention interval. These data provide additional evidence that left lateral prefrontal cortex is important in monitoring specific source information and new evidence that older adults' source memory deficits may be related, in part, to reduced function of this brain area.

Source memory in older adults: an encoding or retrieval problem?

Source memory has been found to be more affected by aging than item memory, possibly because of declining frontal function among older adults. In 4 experiments, the authors explored the role of the frontal lobes (FLs) in source memory, the extent to which they may be involved in the encoding and/or retrieval of source or context, and the conditions under which the source memory deficit in older people may be reduced or eliminated. Results indicated that only a subset of older adults show deficits in source memory, namely those with below average frontal function, and these deficits can be eliminated by requiring people at study to consider the relation between an item and its context. These results provide convincing evidence of the importance of frontal function during the encoding of source and suggest that older adults with reduced FL function fail to initiate the processes required to integrate contextual information with focal content during study.

Aging and interference in verbal working memory.

According to inhibitory views of working memory, old adults should have particular problems deleting irrelevant information from working memory, leading to greater interference effects compared with young adults. The authors investigated this hypothesis by using variations of an A-B, C-D retroactive interference paradigm in working memory with young and old adults. They used a recognition measure of memory, assessing both accuracy and reaction time. The primary finding was that senior adults consistently exhibited proportionally greater retroactive interference effects compared with young adults when interfering word pairs that had been read aloud had to be rejected. Patterns of recognition and reaction time data suggested that old adults' activation of target material is similar to young adults, but they experience sustained activation of irrelevant material that has entered working memory. Theoretical implications of these findings for inhibitory deficit (R. T. Zacks & L. Hasher, 1998) and source memory deficit accounts of cognitive aging are discussed.

Pathological False Recognition and Source Memory Deficits Following Frontal Lobe Damage

Pathological False Recognition and Source Memory Deficits Following Frontal Lobe Damage

Pathological false recognition and source memory deficits following frontal lobe damage

Pathological false recognition and source memory deficits following frontal lobe damage

Pathological false recognition and source memory deficits following frontal lobe damage

This study documents a patient (MR) with a demyelinating illness centred on the left frontal lobe who presents with severe memory difficulties in both recall and recognition memory tests. His performance on the latter is characterized by pathologically high false-alarm rates together with unimpaired hit rates. False-alarm rates are not affected by having targets and distractors that are similar to each other (e.g. synonyms) and remain high when inherently unfamiliar stimuli are used (e.g. non-words). This suggests that MR is not over-reliant on familiarity cues. It is suggested, instead, that MR has difficulties in establishing a focused memory description of the target items, such that the memory description that he forms contains features that are common to many items (including distractors) and lacks itemspecific distinctive information. A number of lines of evidence are presented which support this interpretation. For instance, orienting instructions (which may alter the featural composition of the target memories) may be used to attenuate false recognition and MR is impaired at making source attribution judgements (which requires item-specific information) about targets that are correctly recognized.

Source memory in major depression

Background: Research demonstrating episodic memory deficits in clinical depression has dealt with item memory exclusively. The present research sought to determine whether memory for source is differentially affected by depression. Methods: Patients with major depression and normal control subjects were examined in item memory and two types of source memory, requiring discriminations between (e.g. something that the subject said and something another person said) and within (e.g. something that one person said and something another person said) classes. Results: Depression-related deficits in item memory were exacerbated in source memory. However, deficits in source memory in depressed patients were restricted to those conditions requiring within-class discriminations. Conclusion: The overall pattern of results may reflect that those symptoms of major depression that affect the individuals basic processing resources (e.g. concentration difficulties, lack of effort, loss of energy) results in an impairment of episodic memory, particularly when the demands of differentiating perceptual and cognitive information are high.

Repetition‐Induced Belief in the Elderly: Rehabilitating Age‐Related Memory Deficits

This research examines the impact of age-related deficits in recognition and source memory on repetition-induced increases in belief in fictitious statements (the “truth effect”). Young and elderly subjects made recognition-memory judgments and rated the credibility of new and previously presented statements. Experiment 1 assessed the level of memory impairment in the elderly, as compared to the young, and its influence on the truth effect. The elderly, who had a greater tendency to make false-alarm errors in recognition and had poorer source memory for the claims, were more susceptible to the truth-inflating effect of repetition than were the young. Deeper (semantic vs. perceptual) processing was ineffective in reducing age-related deficits in memory or sensitivity to repetition-induced beliefs. Experiment 2 demonstrated that an imagery encoding task did provide more environmental support (a greater improvement in recognition and source memory for the elderly than the young) than did a perceptual encoding task. When both young and elderly subjects engaged in an imagery task during encoding, their memory performance was equivalent and age-related differences in the truth effect were abolished. Thus, it appears that the elderly are more susceptible to the truth-inflating effect of repetition, and this effect seems to be mediated via their poor memory. However, if memory is enhanced using environmental support, the elderly are no longer especially vulnerable to the truth effect.

Source memory deficits and frontal lobe functioning in children

Thirty‐three children (aged 10 to 14 years old) were presented with a number of fictitious facts about famous individuals (e.g., Sylvester Stallone's favorite color is green). Subjects’ memories for this information was assessed by measures of fact recall (e.g., What is Sylvester Stallone's favorite color?) and source recall (e.g., Where did you first learn that green is Sylvester Stallone's favorite color?). Furthermore, all subjects were administered tests sensitive to frontal lobe functioning: the Wisconsin Card Sorting Test (WCST) and a verbal fluency task. The incidence of errors on the source recall task was found to be related to children's performance on the WCST. Importantly, source error rates were not related to fact recall, digit span, or age. These results are consistent with previous findings that have documented a relationship between performance on tasks of frontal lobe function and source memory deficits in neurological patients as well as healthy, community‐dwelling elderly.

Source memory: extending the boundaries of age-related deficits.

Previous research has established that elderly adults can exhibit impaired memory for the source of newly acquired facts even when levels of fact recall in old and young do not differ. However, source memory impairments have been observed only under conditions of many-to-1 mapping: A large number of facts are related to either of 2 sources. It is thus possible that apparent source memory impairments reflect a more general age-related problem in handling many-to-1 mappings. Two experiments provide evidence against this possibility by demonstrating age-related source memory deficits with 1-to-1 mapping between facts and sources. The data also indicate that source memory deficits are observed across encoding tasks that manipulate the allocation of attention to the source or to the fact.

The relation between source memory and aging.

Previous research has shown that elderly adults have difficulty recalling the source of recently acquired facts but does not indicate whether source memory is more impaired than fact memory. This study examined old and young subjects' memory for novel facts that had been read to them by 1 of 2 experimental sources either in a random order or in a blocked order. When fact memory was equated in young and old at different levels of performance, the elderly exhibited disproportionate source memory deficits in the blocked condition but not in the random condition. Results suggest that the relation between fact and source memory in the elderly varies across experimental conditions.

The relation between source memory and aging.

Previous research has shown that elderly adults have difficulty recalling the source of recently acquired facts but does not indicate whether source memory is more impaired than fact memory. This study examined old and young subjects' memory for novel facts that had been read to them by 1 of 2 experimental sources either in a random order or in a blocked order. When fact memory was equated in young and old at different levels of performance, the elderly exhibited disproportionate source memory deficits in the blocked condition but not in the random condition. Results suggest that the relation between fact and source memory in the elderly varies across experimental conditions.