VARIETIES OF FALSE MEMORY

Journeying to the past: time travel and mental time travel, how far apart?

Spatial models dominated memory research throughout much of the twentieth century, but in recent decades, the concept of memory as a form of mental time travel (MTT) to the past has gained prominence. Initially introduced as a metaphor, the MTT perspective shifted the focus from internal memory processes to the subjective conscious experience of remembering. Despite its significant impact on empirical and theoretical memory research, there has been limited discussion regarding the meaning and adequacy of the MTT metaphor in accounting for memory. While in previous work I have addressed the general limitations of the MTT metaphor in explaining memory, the objective of this article is more focused and modest: to gain a better understanding of what constitutes MTT to the past. To achieve this objective, a detailed analysis of the characteristics of MTT to the past is presented through a comparison with time travel (TT) to the past. Although acknowledging that TT does not refer to an existing physical phenomenon, it is an older concept extensively discussed in the philosophical literature and provides commonly accepted grounds, particularly within orthodox theories of time, that can offer insights into the nature of MTT. Six specific characteristics serve as points of comparison: (1) a destination distinct from the present, (2) the distinction between subjective time and objective time, (3) the subjective experience of the time traveler, (4) their differentiation from the past self, (5) the existence of the past, and (6) its unchangeability. Through this research, a detailed exploration of the phenomenal and metaphysical aspects of MTT to the past is undertaken, shedding light on the distinct features that mental time travel to the past acquires when it occurs within the realm of the mind rather than as a physical phenomenon. By examining these characteristics, a deeper understanding of the nature of mental time travel is achieved, offering insights into how it operates in relation to memory and the past.

Substance abuse and susceptibility to false memory formation: a systematic review and meta-analysis

Background

Substance abuse has an impact on various cognitive domains, including memory. Even though this impact has been extensively examined across different subdomains, false memory has been sparsely studied. This systematic review and meta-analysis seek to synthesize the current scientific data concerning false memory formation in individuals with a history of substance abuse.

Methods

PubMed, Scopus, the Cochrane Library, Web of Science, and PsycINFO were searched to identify all experimental and observational studies in English, Portuguese, and Spanish. Studies were then examined by four independent reviewers and, if they met the inclusion criteria, assessed for their quality. The Cochrane Risk of Bias Tool for randomized controlled trials (RCT) and the Joanna Briggs Institute (JBI) critical appraisal checklists for quasi-experimental and analytic cross-sectional studies were used to assess the risk of bias.

Results

From the 443 screened studies, 27 (and two more from other sources) were considered eligible for full-text review. A final 18 studies were included in the present review. Of these, 10 were conducted with alcoholics or heavy drinkers, four focused on ecstasy/polydrug users, three were done with cannabis users and one focused on methadone maintenance patients with current cocaine dependence. Regarding false memory type, 15 studies focused on false recognition/recall, and three on provoked confabulation.

Conclusions

None but one of the studies considering false recognition/recall of critical lures found any significant differences between individuals with a history of substance abuse and healthy controls. However, most of the studies taking into account false recognition/recall of related and unrelated events found that individuals with a history of substance abuse showed significantly higher rates of false memories than controls. Future research should continue to consider different types of false memories as well as their potential association with relevant clinical variables.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=266503, identifier: CRD42021266503.

Hazy memories in the courtroom: A review of alcohol and other drug effects on false memory and suggestibility

Alcohol and other psychoactive drugs are oftentimes implicated in legal cases. A pertinent question herein is whether such substances might adversely affect testimonies of victims, eyewitnesses, or suspects by propelling the formation of false memory and increasing susceptibility to suggestion. In the current review, we amassed all available evidence on the effects of intoxication on false memory formation and suggestibility, including the substances alcohol, benzodiazepines, cannabis, stimulants, hallucinogens, and antipsychotics. Our review indicated that alcohol and cannabis under certain conditions increased the susceptibility to false memories and/or suggestion with effect sizes ranging from medium to large. When intoxicated during an event, alcohol is most likely to increase this susceptibility at high intoxication levels or after a delay, whereas cannabis exerts detrimental effects during acute intoxication but not necessarily once sober. For other substances, ecologically valid research separating different memory phases is needed. Overall, differences between substances regarding false memory effects exist, suggesting that a nuanced approach is needed when dealing with intoxicated individuals in a legal context.

Individual differences impact memory for a crime: A study on executive functions resources

Previous studies demonstrated that memory accuracy is affected by the availability of the individual's cognitive resources. A predominant role in complex cognition has been postulated for executive functions (EF). The aim of the present study was to verify if there are differences in remembering a crime with respect to the individual's EF availability (i.e., Shifting, Inhibition, and Updating). We showed participants a video of a violent crime. Next, they were requested to imagine to be an eyewitness of the crime and report a testimony as detailed as possible. A subsequent memory test was run after ten days. EF resources were assessed in a third session through three neuropsychological tasks. Findings showed that high EF individuals reported more correct details and fewer memory distortions (i.e., omissions and commissions) than low EF individuals. Our results underline that individual EF resources are implicated in the recalling of an event.

Multinomial models reveal deficits of two distinct controlled retrieval processes in aging and very mild Alzheimer disease

Dual-process models of episodic retrieval reveal consistent deficits of controlled recollection in aging and Alzheimer disease (AD). In contrast, automatic familiarity is relatively spared. We extend standard dual-process models by showing the importance of a third capture process. Capture produces a failure to attempt recollection, which might reflect a distinct error from an inability to recollect when attempted (Jacoby et al. Journal of Experimental Psychology: General, 134(2), 131-148, 2005a). We used multinomial process tree (MPT) modeling to estimate controlled recollection and capture processes, as well as automatic retrieval processes, in a large group of middle-aged to older adults who were cognitively normal (N = 519) or diagnosed with the earliest detectable stage of AD (N = 107). Participants incidentally encoded word pairs (e.g., knee bone). At retrieval, participants completed cued word fragments (e.g., knee b_n_) with primes that were congruent (e.g., bone), incongruent (e.g., bend), or neutral (i.e., &&&) to the target (e.g., bone). MPT models estimated retrieval processes both at the group and the individual levels. A capture parameter was necessary to fit MPT models to the observed data, suggesting that dual-process models of this task can be contaminated by a capture process. In both group- and individual-level analyses, aging and very mild AD were associated with increased susceptibility to capture, decreased recollection, and no differences in automatic influences. These results suggest that it is important to consider two distinct modes of attentional control when modeling retrieval processes. Both forms of control (recollection and avoiding capture) are particularly sensitive to cognitive decline in aging and early-stage AD.

The epistemic innocence of clinical memory distortions

In some neuropsychological disorders, distorted reports seem to fill gaps in people's memory of their past, where people's self-image, history, and prospects are often enhanced. False beliefs about the past compromise both people's capacity to construct a reliable autobiography and their trustworthiness as communicators. However, such beliefs contribute to people's sense of competence and self-confidence, increasing psychological well-being. Here, we consider both the psychological benefits and epistemic costs and argue that distorting the past is likely to also have epistemic benefits that cannot be obtained otherwise, such as enabling people to exchange information, receive feedback, and retain key beliefs about themselves.

Everyday false memories in older persons with depressive disorder

Generally we tend to think that memory in daily living is complete and accurate in healthy persons. However, current memory research has revealed inconspicuous memory faults. Rarely omissions and distortions of memory are researched with tasks resembling everyday life. We investigated healthy older control subjects (HC) and patients with depressive disorder (DD). Cognitive function was assessed with a comprehensive neuropsychological test battery and mood with the Montgomery-Asberg Depression Scale (MADRS). We assessed everyday veridical and distorted memories on showing participants original news and commercials. In most aspects of attention, executive functions, and memory, patients with DD performed worse than HC. Regarding memory content on viewing news or commercials the difference between patients with DD and HC was more pronounced for false memory content than for veridical memory content. Linear regression analysis showed the extent of false memory content being associated with mental flexibility as assessed with the Trail Making Test and mood as assessed with the MADRS for both information obtained on viewing news and commercials. Increase of false memories impedes overall accuracy of memory more than decrease of veridical memories in older persons with depressive disorder. Diminished executive functions and depressive mood partly explain these memory distortions.

Ownership illusions in patients with body delusions: Different neural profiles of visual capture and disownership

The various neurocognitive processes contributing to the sense of body ownership have been investigated extensively in healthy participants, but studies in neurological patients can shed unique light into such phenomena. Here, we aimed to investigate whether visual capture by a fake hand (without any synchronous or asynchronous tactile stimulation) affects body ownership in a group of hemiplegic patients with or without disturbed sensation of limb ownership (DSO) following damage to the right hemisphere. We recruited 31 consecutive patients, including seven patients with DSO. The majority of our patients (64.5% overall and up to 86% of the patients with DSO) experienced strong feelings of ownership over a rubber hand within 15 sec following mere visual exposure, which correlated with the degree of proprioceptive deficits across groups and in the DSO group. Using voxel-based lesion-symptom mapping analysis, we were able to identify lesions associated with this pathological visual capture effect in a selective fronto-parietal network, including significant voxels (p < .05) in the frontal operculum and the inferior frontal gyrus. By contrast, lesions associated with DSO involved more posterior lesions, including the right temporoparietal junction and a large area of the supramarginal gyrus, and to a lesser degree the middle frontal gyrus. Thus, this study suggests that our sense of ownership includes dissociable mechanisms of multisensory integration.

Confabulation in children with autism

Some children with high-functioning autistic spectrum conditions (ASC) have been noted clinically to produce accounts and responses akin to confabulations in neurological patients. Neurological confabulation is typically associated with abnormalities of the frontal lobes and related structures, and some forms have been linked to poor performance on source monitoring and executive function tasks. ASC has also been linked to atypical development of the frontal lobes, and impaired performance on source monitoring and executive tasks. But confabulation in autism has not to our knowledge previously been examined experimentally. So we investigated whether patterns of confabulation in autism might share similarities with neurologically-based confabulation. Tests of confabulation elicitation, source monitoring (reality monitoring, plus temporal and task context memory) and executive function were administered to four adolescents with ASC who had previously been noted to confabulate spontaneously in everyday life. Scores were compared to a typically developing (TD) and an ASC control group. One confabulating participant was significantly impaired at reality monitoring, and one was significantly worse at a task context test, relative to both the ASC and TD controls. Three of the confabulators showed impairment on measures of executive function (Brixton test; Cognitive Estimates test; Hayling Test B errors) relative to both control groups. Three were significantly poorer than the TD controls on two others (Hayling A and B times), but the ASC control group was also significantly slower at this test than the TD controls. Compared to TD controls, two of the four confabulating participants produced an abnormal number of confabulations during a confabulation elicitation questionnaire, where the ASC controls and TD controls did not differ from each other. These results raise the possibility that in at least some cases, confabulation in autism may be less related to social factors than it is to impaired source memory or poor executive function.

Memory distrust syndrome, confabulation and false confession

There are three types of false confessions: 'voluntary', 'pressured-compliant' and 'pressured-internalized'. On the basis of case studies, in the early 1980s Gudjonsson and MacKeith coined the term 'memory distrust syndrome (MDS)' to describe a condition where people develop profound distrust of their memory and become susceptible to relying on external cues and suggestions from others. Memory distrust can, under certain circumstances, lead to a false confession, particularly of the pressured-internalized type, described as 'confabulation'. This article reviews the evidence for the condition and the psychological mechanism and processes involved. A heuristic model is then presented of a 32 year old man who falsely confessed to murder whilst in police custody. The key elements of the model involve the impact of 'contextual risk factors' (i.e., isolation, long and persistent guilt presumptive interrogation, and high emotional intensity) on 'enduring' vulnerability and 'acute state' factors. The detainee had kept a detailed diary whilst in solitary confinement that provided a unique insight into the gradual development of a MDS, his mental state, and thinking process. This type of false confession is apparently quite rare, but it can occur in intellectually able and educated individuals and involves 'delayed' rather than 'immediate' suggestibility.

Impaired personal trait knowledge, but spared other-person trait knowledge, in an individual with bilateral damage to the medial prefrontal cortex

Functional neuroimaging has revealed that in healthy adults retrieval of personal trait knowledge is associated with increased activation in the medial prefrontal cortex (mPFC). Separately, neuropsychology has shown that the self-referential nature of memory can be disrupted in individuals with mPFC lesions. However, it remains unclear whether damage to the mPFC impairs retrieval of personal trait knowledge. Therefore, in this neuropsychological case study we investigated the integrity of personal trait knowledge in J.S., an individual who sustained bilateral damage to the mPFC as a result of an anterior communicating artery aneurysm. We measured both accuracy and consistency of J.S.'s personal trait knowledge as well as his trait knowledge of another, frequently seen person, and compared his performance to a group of healthy adults. Findings revealed that J.S. had severely impaired accuracy and consistency of his personal trait knowledge relative to control participants. In contrast, J.S.'s accuracy and consistency of other-person trait knowledge was intact in comparison to control participants. Moreover, J.S. showed a normal positivity bias in his trait ratings. These results, albeit based on a single case, implicate the mPFC as critical for retrieval of personal trait knowledge. Findings also cast doubt on the likelihood that the mPFC, in particular the ventral mPFC, is necessary for storage and retrieval of trait knowledge of other people. Therefore, this case study adds to a growing body of evidence that mPFC damage can disrupt the link between self and memory.

False Memories for Affective Information in Schizophrenia

Studies have shown a direct link between memory for emotionally salient experiences and false memories. In particular, emotionally arousing material of negative and positive valence enhanced reality monitoring compared to neutral material since emotional stimuli can be encoded with more contextual details and thereby facilitate the distinction between presented and imagined stimuli. Individuals with schizophrenia appear to be impaired in both reality monitoring and memory for emotional experiences. However, the relationship between the emotionality of the to-be-remembered material and false memory occurrence has not yet been studied. In this study, 24 patients and 24 healthy adults completed a false memory task with everyday episodes composed of 12 photographs that depicted positive, negative, or neutral outcomes. Results showed how patients with schizophrenia made a higher number of false memories than normal controls (p < 0.05) when remembering episodes with positive or negative outcomes. The effect of valence was apparent in the patient group. For example, it did not affect the production causal false memories (p > 0.05) resulting from erroneous inferences but did interact with plausible, script consistent errors in patients (i.e., neutral episodes yielded a higher degree of errors than positive and negative episodes). Affective information reduces the probability of generating causal errors in healthy adults but not in patients suggesting that emotional memory impairments may contribute to deficits in reality monitoring in schizophrenia when affective information is involved.

Is there a positive bias in false recognition? Evidence from confabulating amnesia patients

Although there is some evidence for a positive emotional bias in the content of confabulations in brain damaged patients, findings have been inconsistent. The present study used the semantic-associates procedure to induce false recall and false recognition in order to examine whether a positive bias would be found in confabulating amnesic patients, relative to non-confabulating amnesic patients and healthy controls. Lists of positive, negative and neutral words were presented in order to induce false recall or false recognition of non-presented (but semantically associated) words. The latter were termed 'critical intrusions'. Thirteen confabulating amnesic patients, 13 non-confabulating amnesic patients and 13 healthy controls were investigated. Confabulating patients falsely recognised a higher proportion of positive (but unrelated) words, compared with non-confabulating patients and healthy controls. No differences were found for recall memory. Signal detection analysis, however, indicated that the positive bias for false recognition memory might reflect weaker memory in the confabulating amnesic group. This suggested that amnesia patients with weaker memory are more likely to confabulate and the content of these confabulations are more likely to be positive.

Puzzling Confabulations – An Overview of Classifications and Theories

Abstract. Confabulations comprise a puzzling collection of false statements, produced without conscious intent to deceive. They have been classified according to the mode of elicitation (spontaneous vs. provoked), the content (fantastic vs. plausible), the memory domain in which they become manifest (episodic vs. semantic), their stability (stable vs. ephemeral), or their selectivity (monothematic vs. multithematic). All classifications appear to be problematic, because there are no clear-cut dichotomies, and confabulations often seem to fall into overlapping categories. There are, in fact, many theories, presumably explaining different kinds of confabulations; the best bet is to regard them as complementary rather than competing.

Telling true from false: cannabis users show increased susceptibility to false memories

Previous studies on the neurocognitive impact of cannabis use have found working and declarative memory deficits that tend to normalize with abstinence. An unexplored aspect of cognitive function in chronic cannabis users is the ability to distinguish between veridical and illusory memories, a crucial aspect of reality monitoring that relies on adequate memory function and cognitive control. Using functional magnetic resonance imaging, we show that abstinent cannabis users have an increased susceptibility to false memories, failing to identify lure stimuli as events that never occurred. In addition to impaired performance, cannabis users display reduced activation in areas associated with memory processing within the lateral and medial temporal lobe (MTL), and in parietal and frontal brain regions involved in attention and performance monitoring. Furthermore, cannabis consumption was inversely correlated with MTL activity, suggesting that the drug is especially detrimental to the episodic aspects of memory. These findings indicate that cannabis users have an increased susceptibility to memory distortions even when abstinent and drug-free, suggesting a long-lasting compromise of memory and cognitive control mechanisms involved in reality monitoring.

Confabulations in schizophrenia

INTRODUCTION

Current theories of confabulation are based primarily on the observation of neurological patients. The present paper evaluates these theories based on evidence from schizophrenia. Schizophrenia is unique in that it presents with a pathophysiology which differs from that of other neuropsychiatric conditions, and yet the candidate's deficits that various theories of confabulation implicate are often simultaneously present in schizophrenia.

METHODS

A selective review of literature on schizophrenic and neurological confabulations was undertaken.

RESULTS

Schizophrenic confabulation differs from neurological confabulation in terms of its characteristic features and association with symptoms, cognition and linguistic functions. Current evidence also suggests that confabulation may be conceptualized as a special class of delusions pertaining to memory phenomena.

CONCLUSIONS

Schizophrenia presents with confabulations that cannot be fully accounted for by the existing theories. It also presents with confabulations with unique features, which have different cognitive correlates and relation to other symptoms of the condition.

A hypnotic analogue of clinical confabulation

Confabulation-fabricated or distorted memories about oneself-occurs in many disorders, but there is no reliable technique for investigating it in the laboratory. The authors used hypnosis to model clinical confabulation by giving subjects a suggestion for either (a) amnesia for everything that had happened since they started university, (b) amnesia for university plus an instruction to fill in memory gaps, or (c) confusion about the temporal order of university events. They then indexed different types of memory on a confabulation battery. The amnesia suggestion produced the most confabulation, especially for personal semantic information. Notably, subjects confabulated by making temporal confusions. The authors discuss the theoretical implications of this first attempt to model clinical confabulation and the potential utility of such analogues.

False memories to emotional stimuli are not equally affected in right- and left-brain-damaged stroke patients

Previous research has attributed to the right hemisphere (RH) a key role in eliciting false memories to visual emotional stimuli. These results have been explained in terms of two right-hemisphere properties: (i) that emotional stimuli are preferentially processed in the RH and (ii) that visual stimuli are represented more coarsely in the RH. According to this account, false emotional memories are preferentially produced in the RH because emotional stimuli are both more strongly and more diffusely activated during encoding, leaving a memory trace that can be erroneously reactivated by similar but unstudied emotional items at test. If this right-hemisphere hypothesis is correct, then RH damage should result in a reduction in false memories to emotional stimuli relative to left-hemisphere lesions. To investigate this possibility, groups of right-brain-damaged (RBD, N=15), left-brain-damaged (LBD, N=15) and healthy (HC, N=30) participants took part in a recognition memory experiment with emotional (negative and positive) and non-emotional pictures. False memories were operationalized as incorrect responses to unstudied pictures that were similar to studied ones. Both RBD and LBD participants showed similar reductions in false memories for negative pictures relative to controls. For positive pictures, however, false memories were reduced only in RBD patients. The results provide only partial support for the right-hemisphere hypothesis and suggest that inter-hemispheric cooperation models may be necessary to fully account for false emotional memories.

Psychosis, agnosia, and confabulation: an alternative two-factor account

INTRODUCTION

Theories of delusions which rely on a combination of abnormal experience and defective belief evaluation and/ or cognitive bias are the subject of an emerging consensus. This paper challenges the validity of these theories and constructs a two factor alternative.

METHODS

The paper starts by identifying the difficulty the current theories have explaining the complex delusions of schizophrenia and then, by considering, first, the aetiology of somatopsychotic symptoms, and second, the literature on the relationship between confabulation and allopsychotic symptoms, demonstrates that the natural solution is to retain the experiential factor whilst replacing the second factor with confabulation.

RESULTS

The paper is then able to demonstrate that the resultant two-factory theory can clarify recent work on the aetiological role of autonoetic agnosia and on the relationships between confabulation, delusion, and thought disorder.

CONCLUSIONS

The theory supersedes currently available theories in terms of its simplicity, fruitfulness, scope and conservatism and represents an advance in the search for unified theory of psychosis.

Memory consolidation in humans: new evidence and opportunities

We are endlessly fascinated by memory; we desire to improve it and fear its loss. While it has long been recognized that brain regions such as the hippocampus are vital for supporting memories of our past experiences (autobiographical memories), we still lack fundamental knowledge about the mechanisms involved. This is because the study of specific neural signatures of autobiographical memories in vivo in humans presents a significant challenge. However, recent developments in high-resolution structural and functional magnetic resonance imaging coupled with advanced analytical methods now permit access to the neural substrates of memory representations that has hitherto been precluded in humans. Here, I describe how the application of 'decoding' techniques to brain-imaging data is beginning to disclose how individual autobiographical memory representations evolve over time, deepening our understanding of systems-level consolidation. In particular, this prompts new questions about the roles of the hippocampus and ventromedial prefrontal cortex and offers new opportunities to interrogate the elusive memory trace that has for so long confounded neuroscientists.

Focal retrograde amnesia and the attribution of causality: An exceptionally critical view

A detailed critique of the literature on focal retrograde amnesia is provided. Some of the cases commonly cited in this literature had, in fact, severely impaired anterograde memory, most often involving visuospatial material. Other cases showed poor anterograde memory in more moderate or subtle form, begging the question of whether "like" had really been compared with "like" across the retrograde and anterograde domains: there may be alternative explanations for the observed patterns of performance. One suggestion is that these patients suffer an impairment of long-term consolidation, an attractive hypothesis but one which requires much more rigorous testing than has occurred to date and which implies that the underlying problem is not specific to retrograde memory. Moreover, within the literature on cases of focal retrograde amnesia, differing patterns of performance on tests of autobiographical memory or remote semantic knowledge have been reported, and sometimes these may have reflected factors other than the sites of lesions. Many of the most convincing cases in this literature have been those in whom there was an initially severe anterograde amnesia as well as an extensive retrograde loss: in these cases, the critical issue is what determines differential patterns of recovery across these domains-it is likely that both physiological and psychological factors are important. A second, somewhat different, group are patients with semantic dementia, who show a pronounced recency effect in remote memory but, in these cases, the most parsimonious explanation may be in terms of predominantly semantic/linguistic and/or strategic factors. A third group are those with transient epileptic amnesia but, in these cases, the memory gaps may reflect past (anterograde) ictal activity. A fourth group are those in whom psychogenic factors may well be relevant. Although it is difficult to "prove" psychological causation, the logical difficulties in attributing causation where brain lesions are either very subtle or multiple have been considerably underestimated in the neuropsychological literature. Given these problems, in uncertain or equivocal cases, it is as critical to present the relevant psychological data for the reader to evaluate as it is to provide the pertinent memory test scores: this is underemphasised in many of the studies reviewed. Publication of cases in the absence of such data may lead to faulty clinical, neuropsychological, and cognitive conclusions. Abbreviations : AA: anterograde amnesia; AMI: Autobiographical Memory Interview; PTA: posttraumatic amnesia; RA: retrograde amnesia; RMT: Recognition Memory Test; TEA: transient epileptic amnesia; TGA: transient global amnesia; WMS: Wechsler Memory Scale.

Confabulations are emotionally charged, but not always for the best

There is disagreement regarding the underlying basis of confabulation and, in particular, whether emotional mechanisms influence the presence or the content of confabulations. In this study, we have examined the emotional content of confabulations and "true" memories given by 24 memory-disordered patients on two autobiographical memory tasks. Two judges made pleasant/neutral/unpleasant ratings. Although many of the "memories" were evaluated as "neutral", there was an enhanced level of statements rated as having affective content (either pleasant or unpleasant) amongst these patients' confabulations, compared with their "true" memories. This affective bias was present irrespective of whether patients had suffered focal pathology extending to the ventro-medial frontal cortex (VMFC) or other pathology. There was also a correlation between participants' self-evaluated mood-states and both true and false memories' affective content, suggestive of a mood congruency effect in both types of memory. In summary, there was an enhanced tendency to produce memories with affective content (pleasant and unpleasant) amongst confabulations (whether or not there was VMFC pathology). The affective content of both confabulations and true memories produced may relate, in part, to an individual's current mood-state.

Memory monitoring failure in confabulation: evidence from the semantic illusion paradigm

Several prominent models of confabulation characterize the syndrome as a failure in controlled aspects of memory retrieval, such as pre-retrieval cue specification and post-retrieval monitoring. These models have been generated primarily in the context of studies of autobiographical memory retrieval. Less research has focused on the existence and mechanisms of semantic confabulation. We examined whether confabulation extends to the semantic domain, and if so, whether it could be understood as a monitoring failure. We focus on post-retrieval monitoring by using a verification task that minimizes cue specification demands. We used the semantic illusion paradigm that elicits erroneous endorsement of misleading statements (e.g., "Two animals of each kind were brought onto the Ark by Moses before the great flood") even in controls, despite their knowing the correct answer (e.g., Noah). Monitoring demands were manipulated by varying semantic overlap between target and foils, ranging from high semantic overlap to unrelated. We found that semantic overlap modulated the magnitude of semantic illusion in all groups. Compared to controls, both confabulators and non-confabulators had greater difficulty monitoring semantically related foils; however, elevated endorsement of unrelated foils was unique to confabulators. We interpret our findings in the context of a two-process model of post-retrieval monitoring.

Confabulation and delusion: a common monitoring framework

Confabulations and delusions both involve the production of false claims. Although they may have different types of content, they share several characteristics. For example, they are often held with considerable conviction and are resistant to counter evidence, they may be acted upon, and they may be accompanied by a lack of concern about the false claim or its implications. Confabulations and delusions may initially arise from failures in different systems (e.g., mnemonic vs. perceptual or affective). However, their shared characteristics raise the possibility that the monitoring deficits involved might be the same, resulting in failure to reject the confabulatory or delusional ideas. In this paper we will focus on the nature of these common monitoring deficits. Critically, we argue that monitoring in confabulation and delusion involves both unconscious and conscious processes. We propose that an unconscious process is responsible for tagging suspect content which needs to be checked for veracity by a separate set of conscious evaluative processes. Failure of these monitoring processes would allow ideas which ought to be checked and rejected to instead be uncritically accepted: This would result in the production of confabulations or delusions. Importantly, inclusion of both unconscious and conscious monitoring stages allows the model to account for both "endorsement" and "explanation" delusions, and both "primary" and "secondary" confabulations. Our hope is that this model may provide a theoretical framework to guide empirical investigation of the commonalities and differences between the conditions.

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.

Varieties of confabulation and delusion

INTRODUCTION

Different types of confabulation or false memory can arise from brain disease. There are competing explanatory theories for the mechanisms underlying confabulation. Recent literature has attempted to relate the notion of delusion to that of confabulation.

METHOD

A brief review of the literature relating to these ideas.

RESULTS

The varieties of confabulation or false memory that can arise from brain disease are considered. The varieties of delusion and the contexts in which they arise are considered. Comparisons are made between the characteristics of spontaneous confabulation and those of delusional memory.

CONCLUSION

It is suggested that global theories purporting to account for both confabulation and delusions, in whatever circumstances they arise, can have only limited explanatory power. On the other hand, there are resemblances between confabulation and delusional memory, and the similarities and differences between these phenomena deserve further empirical investigation.

The role of personal biases in the explanation of confabulation

INTRODUCTION

Previous research has demonstrated that motivational forces play an important role in determining the content of confabulation. In particular the content of confabulation has been shown to contain a positive emotional bias. This study investigated the role of personal biases in the confabulations of six patients with diverse aetiologies.

METHOD

Confabulations were elicited with a series of structured interviews. We then compared the patients' confabulations to their actual situations. Further analyses compared confabulations about current (i.e., the postmorbid period) and past (i.e., premorbid events and general life circumstances) events.

RESULTS

Group analysis confirmed a general bias to recall events that were more positive than the reality. However, examination of individual cases revealed that positive biases were not universal. Confabulations about current circumstances showed the positive bias, whereas an emotional bias was not evident in past confabulations.

CONCLUSION

We conclude that motivational forces play a role in determining the content of confabulations but conceive of this role primarily in terms of a need to maintain a consistent self-concept (whether positive or negative) overlaid upon the ease with which an individual can retrieve familiar premorbid daily activities and routines.

The affective neuropsychology of confabulation and delusion

The paper reviews the history of the scientific understanding of the role of emotion in confabulation and delusion. I argue that the significance of emotion in the pathogenesis of these symptoms was obscured by academic polarisation between psychodynamic and neurocognitive traditions and was also often obfuscated by rigid distinctions between psychogenic and neurogenic explanations. This tradition of epistemic dualism was implicitly maintained in the fields of cognitive neuropsychology and cognitive neuropsychiatry. This paper focuses on memory-related confabulation following ventromedial frontal lobe lesions, awareness-related confabulation following right perisylvian lesions, and delusions of various aetiologies. Ambiguity regarding the definition and taxonomy of symptoms renders direct comparison difficult, but certain overriding principles are becoming discernible. Recent findings suggest that emotion and motivation influence both confabulation and delusion. These influences may be instigated directly by neural dysfunction or indirectly by life changes and altered social circumstances, or by a combination of these. Importantly, the rejection of epistemic dualism in the conceptualisation of both symptoms can allow us to study them in parallel and draw conclusions about the relation between cognition and emotion. Specifically, confabulation and delusion can be described as faulty attempts to balance the conflicting demands of accurate and self-serving reality representation.

Delusion and confabulation: mistakes of perceiving, remembering and believing

This paper adopts an inclusive approach to the relationship between delusion and confabulation, according to which some symptoms might qualify as both delusional and confabulatory. Our initial focus is on the cardinal signs of delusions: incomprehensibility, incorrigibility, and subjective conviction. Setting aside post hoc (or secondary) confabulations-plausible rationalisations that might be generated by nonpathological belief formation processes-we focus on spontaneous memory-based confabulations which, we suggest, conform to the characterisation of delusions. After considering current accounts of the role of experience in delusion formation, we propose that spontaneous confabulations are located at (or towards) the "received" end of a "received-reflective" spectrum of delusions: the spontaneous confabulator simply receives and endorses as genuine the content of an apparent-yet implausible-memory experience. Underlying both spontaneous confabulations and other received delusions, we propose, is an inability to inhibit the prepotent tendency to upload and maintain experiential content (mnemonic or perceptual) into belief.

MILD EXECUTIVE DYSFUNCTIONS IN UNDERGRADUATES ARE RELATED TO RECOLLECTING WORDS NEVER PRESENTED

The aim of this study was to explore whether individual differences in executive function in undergraduate students (n = 72) contribute to false recall and recognition as obtained with the Deese/Roediger-McDermott (DRM) paradigm. Participants were subjected to the DRM paradigm and also were given a test designed to assess executive function--the Random Number Generation task (RNG). A relationship was found between heightened seriation on the RNG (indicating a deficiency in the ability to inhibit cognitive schemes) and false recognition of non-presented, critical lure words in the DRM paradigm. This suggests that individual differences in executive function do occur in a healthy population and that the reconstructive activity inherent in memory depends in part on executive functioning.

Confabulation: a spontaneous and fantastic review

Confabulation can be of two types: provoked or spontaneous. The former is the more common and can occur on challenge to an amnesic patient's memory. Spontaneous confabulation involves an unprovoked outpouring of unbelievable autobiographical claims. The purpose of the present paper is to synthesize the current literature on confabulation for the use of treating clinicians. There is a focus on the spontaneous form, which is less common, but more memorable when encountered. In this paper the history, phenomenology, incidence, anatomical underpinnings and theoretical mechanisms of spontaneous confabulations will be reviewed, and then the paper will conclude by addressing prognostic and treatment issues. A systematic literature review of electronic databases was conducted to identify the key articles, reviews and books that have shaped the understanding of spontaneous confabulation.

Confabulation in schizophrenia and its relationship to clinical and neuropsychological features of the disorder

BACKGROUND

A form of confabulation has been documented in schizophrenia and appears to be related to the symptom of thought disorder. It is unclear whether it is associated with the same pattern of neuropsychological deficits as confabulation in neurological patients.

METHOD

Thirty-four patients with chronic schizophrenia, including those with and without thought disorder, and 17 healthy controls were given a fable recall task to elicit confabulation. They were also examined on a range of executive, episodic and semantic memory tests.

RESULTS

Confabulation was seen at a significantly higher rate in the schizophrenic patients than the controls, and predominated in those with thought disorder. Neuropsychologically, it was not a function of general intellectual impairment, and was not clearly related to episodic memory or executive impairment. However, there were indications of an association with semantic memory impairment.

CONCLUSIONS

The findings support the existence of a form of confabulation in schizophrenia that is related to thought disorder and has a different neuropsychological signature to the neurological form of the symptom.

The slave model of autobiographical memory

In this paper the nature of the relationship between psychological mechanisms that process semantic information and those that process autobiographical memory is considered. On the basis of theoretical work by Endel Tulving, and empirical research into the construction of false memories, a novel model of autobiographical memory construction is proposed. This model is referred to as the slave model of autobiographical memory and has that the mechanisms responsible for the production of autobiographical memories are enslaved to those that support semantic information, in the sense that beliefs determine the content of autobiographical memory. Implications of the model for the potential double dissociation of semantic and episodic memory are considered; as are recent accounts of autobiographical memory construction.

On the psychology of confessions: does innocence put innocents at risk?

The Central Park jogger case and other recent exonerations highlight the problem of wrongful convictions, 15% to 25% of which have contained confessions in evidence. Recent research suggests that actual innocence does not protect people across a sequence of pivotal decisions: (a) In preinterrogation interviews, investigators commit false-positive errors, presuming innocent suspects guilty; (b) naively believing in the transparency of their innocence, innocent suspects waive their rights; (c) despite or because of their denials, innocent suspects elicit highly confrontational interrogations; (d) certain commonly used techniques lead suspects to confess to crimes they did not commit; and (e) police and others cannot distinguish between uncorroborated true and false confessions. It appears that innocence puts innocents at risk, that consideration should be given to reforming current practices, and that a policy of videotaping interrogations is a necessary means of protection.

Disordered memory awareness: recollective confabulation in two cases of persistent déjà vecu

We describe two cases of false recognition in patients with dementia and diffuse temporal lobe pathology who report their memory difficulty as being one of persistent déjà vecu--the sensation that they have lived through the present moment before. On a number of recognition tasks, the patients were found to have high levels of false positives. They also made a large number of guess responses but otherwise appeared metacognitively intact. Informal reports suggested that the episodes of déjà vecu were characterised by sensations similar to those present when the past is recollectively experienced in normal remembering. Two further experiments found that both patients had high levels of recollective experience for items they falsely recognized. Most strikingly, they were likely to recollectively experience incorrectly recognised low frequency words, suggesting that their false recognition was not driven by familiarity processes or vague sensations of having encountered events and stimuli before. Importantly, both patients made reasonable justifications for their false recognitions both in the experiments and in their everyday lives and these we term 'recollective confabulation'. Thus, the patients are characterised by false recognition, overextended recollective experience, and recollective confabulation. These features are accounted for in terms of disrupted control of memory awareness and recollective states, possibly following brain damage to fronto-temporal circuits and we extend this account to normally and abnormally occurring states of déjà vu and vecu and related memory experiences.

Comprehension, encoding, and monitoring in the production of confabulation in memory: a study with schizophrenic patients

INTRODUCTION

The aim of the present study was to test the hypotheses proposed by Nathaniel-James and collaborators (Nathaniel-James & Frith, 1996; Nathaniel-James, Foong, & Frith, 1996) to account for the cognitive deficits involved in the production of confabulations in schizophrenic patients: impairments in comprehension, memory encoding, and memory monitoring.

METHOD

Five patients were investigated in this multiple single-case study. Comprehension abilities were investigated in several tests in which a memory bias was avoided. The encoding deficit hypothesis was tested by manipulating cues at encoding and/or retrieval. "Memory monitoring" abilities were examined in two tasks: the Hayling test for all patients and an AB-AC word pairs learning task for two patients.

RESULTS

Four of the patients produced an abnormal level of confabulations in story and fable learning tests. All patients exhibited encoding deficits and specific comprehension difficulties. However, some demonstrated preserved memory monitoring abilities. Across different tests, it was observed that the more the confabulations occurred, the more severe were the comprehension difficulties.

CONCLUSION

The results are in favour of the hypothesis that verbal comprehension difficulties lead to the production of confabulation. They are inconsistent with the idea that memory monitoring impairment is necessarily involved.