Highly Superior Autobiographical Memory (HSAM): A Systematic Review.

Individuals possessing a Highly Superior Autobiographical Memory (HSAM) demonstrate an exceptional ability to recall their own past, excelling most when dates from their lifetime are used as retrieval cues. Fully understanding how neurocognitive mechanisms support exceptional memory could lead to benefits in areas of healthcare in which memory plays a central role and in legal fields reliant on witnesses' memories. Predominantly due to the rareness of the phenomenon, existing HSAM literature is highly heterogenous in its methodologies used. Therefore, following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, we performed the first systematic review on this topic, to collate the existing behavioural, neuroanatomical, and functional HSAM data. Results from the 20 experimental selected studies revealed that HSAM is categorised by rapidly retrieved, detailed and accurate autobiographical memories, and appears to avoid the normal aging process. Functional neuroimaging studies showed HSAM retrieval seems characterised by an intense overactivation of the usual autobiographical memory network, including posterior visual areas (e.g., the precuneus). Structural neuroanatomical differences do not appear to characterise HSAM, but altered hippocampal resting-state connectivity was commonly observed. We discuss theories of HSAM in relation to autobiographical encoding, consolidation, and retrieval, and suggest future directions for this research.

An exploration of Italian laypeople's belief in how human memory works.

We present the first study to measure the beliefs held by Italian laypeople about how human memory works, using a newly developed tool: the Italian Memory Belief Questionnaire (IMBQ). Research conducted in other countries has demonstrated that beliefs about memory vary widely between different professional and non-professional groups, indicating that limitations exist regarding the dissemination of empirically researched scientific knowledge. To ascertain what Italian people understand about memory-related topics, including eyewitness testimony, repression of traumatic memories and factors influencing memory recall, 301 native Italian participants completed the IMBQ in Study 1. In Study 2, 346 additional participants completed the IMBQ, alongside various additional measures, to examine the construct validity of our new instrument and investigate socio-demographic predictors of memory beliefs. Exploratory factor analysis in Study 1 identified three distinct belief factors that were present in the dataset: eyewitness and memory reliability, trauma and remembering and aspects that improve remembering. Study 2 partially confirmed this factor structure and found IMBQ scores to correlate with existing memory belief questionnaires. Correlations were also found between the IMBQ subscales and measures of fantasy proneness, but not dissociation. In both studies, many Italian laypeople strongly endorsed the notion that controversial topics (i.e., repression) are possible. Contrastingly, Italian laypeople do appear to understand the conceivable inaccuracies of memory in eyewitness settings. Sex, age and education were shown to predict beliefs about memory. Findings are discussed in relation to the importance of addressing misinformation about memory, especially in clinical and forensic settings.

Dimensions of a hyper memory: investigating the factors modulating exceptional retrieval in a single case of highly superior autobiographical memory (HSAM).

Highly Superior Autobiographical Memory (HSAM) is a rare form of exceptional memory, characterised by an ability to recall personal episodes in response to dates. The single case "DT" is one of less than 100 HSAM individuals globally, and little is known about how these individuals organise the vast number of events they can recollect. We administered 2 novel priming tasks to explore navigation between autobiographical memories. In both tasks, a "prime" date appeared on the screen and DT was instructed to access and begin reliving a specific memory from that date. After 3 s, a "target" date appeared, and DT switched to the new memory. Latencies were recorded. Experiment 1 explored the influence of emotional valence on memory navigation. DT was quicker moving from positive or negative memories to neutral memories, compared to between neutral memories, supporting the role of emotionality in connecting memories in HSAM. Experiment 2 investigated semantic content and mental timeline configuration's role in organisation. DT was faster moving forward (e.g., 1996-1997) than backwards (e.g., 2023-2022), indicating a forwards perception of time. No differences were observed regarding semantic content. Results provide insight into DT's memory dimensions and support the use of this task to explore organisation.

From vector spaces to DRM lists: False Memory Generator, a software for automated generation of lists of stimuli inducing false memories.

The formation of false memories is one of the most widely studied topics in cognitive psychology. The Deese-Roediger-McDermott (DRM) paradigm is a powerful tool for investigating false memories and revealing the cognitive mechanisms subserving their formation. In this task, participants first memorize a list of words (encoding phase) and next have to indicate whether words presented in a new list were part of the initially memorized one (recognition phase). By employing DRM lists optimized to investigate semantic effects, previous studies highlighted a crucial role of semantic processes in false memory generation, showing that new words semantically related to the studied ones tend to be more erroneously recognized (compared to new words less semantically related). Despite the strengths of the DRM task, this paradigm faces a major limitation in list construction due to its reliance on human-based association norms, posing both practical and theoretical concerns. To address these issues, we developed the False Memory Generator (FMG), an automated and data-driven tool for generating DRM lists, which exploits similarity relationships between items populating a vector space. Here, we present FMG and demonstrate the validity of the lists generated in successfully replicating well-known semantic effects on false memory production. FMG potentially has broad applications by allowing for testing false memory production in domains that go well beyond the current possibilities, as it can be in principle applied to any vector space encoding properties related to word referents (e.g., lexical, orthographic, phonological, sensory, affective, etc.) or other type of stimuli (e.g., images, sounds, etc.).

Hands-on false memories: a combined study with distributional semantics and mouse-tracking.

Although mouse-tracking has been seen as a real-time window into different aspects of human decision-making processes, currently little is known about how the decision process unfolds in veridical and false memory retrieval. Here, we directly investigated decision-making processes by predicting participants' performance in a mouse-tracking version of a typical Deese-Roediger-McDermott (DRM) task through distributional semantic models, a usage-based approach to meaning. Participants were required to study lists of associated words and then to perform a recognition task with the mouse. Results showed that mouse trajectories were extensively affected by the semantic similarity between the words presented in the recognition phase and the ones previously studied. In particular, the higher the semantic similarity, the larger the conflict driving the choice and the higher the irregularity in the trajectory when correctly rejecting new words (i.e., the false memory items). Conversely, on the temporal evolution of the decision, our results showed that semantic similarity affects more complex temporal measures indexing the online decision processes subserving task performance. Together, these findings demonstrate that semantic similarity can affect human behavior at the level of motor control, testifying its influence on online decision-making processes. More generally, our findings complement previous seminal theories on false memory and provide insights into the impact of the semantic memory structure on different decision-making components.

Repeated simulation increases belief in the future occurrence of uncertain events.

The feeling that an imagined event will or will not occur in the future - referred to as belief in future occurrence - plays a key role in guiding our decisions and actions. Recent research suggests that this belief may increase with repeated simulation of future events, but the boundary conditions for this effect remain unclear. Considering the key role of autobiographical knowledge in shaping belief in occurrence, we suggest that the effect of repeated simulation only occurs when prior autobiographical knowledge does not clearly support or contradict the occurrence of the imagined event. To test this hypothesis, we investigated the repetition effect for events that were either plausible or implausible due to their coherence or incoherence with autobiographical knowledge (Experiment 1), and for events that initially appeared uncertain because they were not clearly supported or contradicted by autobiographical knowledge (Experiment 2). We found that all types of events became more detailed and took less time to construct after repeated simulation, but belief in their future occurrence increased only for uncertain events; repetition did not influence belief for events already believed or considered implausible. These findings show that the effect of repeated simulation on belief in future occurrence depends on the consistency of imagined events with autobiographical knowledge.

Do intuitive ideas of the qualities that should characterize involuntary and voluntary memories affect their classification?

It is assumed that the difference between voluntary and involuntary autobiographical memories lies in the intentionality to retrieve a memory assigned by the experimenter. Memories that are retrieved when people are instructed to do so in response to cues are considered voluntary (VAMs), those that pop up spontaneously are considered involuntary (IAMs). VAMs and IAMs so classified are also found to differ in terms of phenomenological characteristics, such as perceived accessibility, vividness etc. These differences are assumed to be due to differences in intentionality and the different retrieval processes at play. It is possible, however, that these differences (which are subjective attributions of phenomenological characteristics) are the result of metacognitive beliefs of what IAMs and VAMs should be. In two experiments, we investigated the possible role of these metacognitive beliefs. Participants rated IAMs and VAMs on a number of phenomenological characteristics in two conditions, when these memories were presented in blocks that specified whether they were retrieved in a voluntary or involuntary task, or when presented in a mixed list with no information provided. If metacognitive beliefs influence the reporting of memory properties, then the block presentation would increase the differences between the characteristics of the two types of memories. The results showed that, besides replicating the characteristics of IAMs and VAMs already observed in the literature, there were almost no differences between the blocked and the mixed lists. We discuss the results as supporting the idea that the difference in characteristics attributed to IAMs and VAMs reflect a genuine difference in the nature of the retrieval and is not the result of pre-existing metacognitive belief on what a voluntary and an involuntary memory should be.

Could direct and generative retrieval be two flips of the same coin? A dual-task paradigm study.

Autobiographical memories are thought to be retrieved using two possible ways: a generative one, which is effortful and follows a general-to-specific pathway, and a direct one, which is automatic and relatively effortless. These two retrieve processes are known to differ on the quantitative side (especially considering retrieval times), from a qualitative point of view; however, evidence is missing. Here, we aimed to disentangle this question by taking advantage of a dual-task paradigm in which the different tasks tax different executive functions. Participants were asked to perform an autobiographical memory task under three different conditions: no cognitive load, non-visual cognitive load and visual cognitive load. On the quantitative side, results replicated previous findings with generative processes being slower compared with direct ones. Conversely, on the qualitative side, results indicated that the retrieval times of both direct and generative retrieval processes varied similarly according to the dual-task condition, thus supporting the idea that the same memory process could underlie both retrievals.

How intention to retrieve a memory and expectation that a memory will come to mind influence the retrieval of autobiographical memories.

While involuntary memories are retrieved with no intention and are usually unexpected (when one is not waiting for a memory to arise), voluntary memories are intended and expected (when one is searching and waiting for a memory to arise). The present study aimed to investigate the effects of retrieval intentionality (i.e. wanting to retrieve a memory) and monitoring processes (i.e. waiting for a memory to appear) during autobiographical memory retrieval. In addition, we introduced two novel laboratory conditions that have not been used in previous research on voluntary memories: in the first, participants were asked to report anything they could think of in response to each cue word; in the second, they could skip a word if nothing came to mind. These novel manipulations allowed us to differentiate between voluntary memories retrieved in response to experimenter-generated cues (when participants were forced to provide a memory or a thought for each cue) and self-selected cues (when participants were free to not answer a cue if they found it too difficult). We found that highly accessible memories were mostly experienced when retrieval was involuntary and unexpected, while memories with low accessibility were accessed through intentional retrieval and monitoring processes. Response times for memories recalled in the experimenter-generated cue conditions were longer compared to the self-selected cue conditions. This novel finding shows that experimenter-generated recall favours memories with low accessibility; it further supports the idea that, in a substantial number of trials, voluntary memories are directly rather than effortfully retrieved. The idea that the driving force behind differences between involuntary and voluntary memories is not the intention per se is further discussed.

Involuntary memories and involuntary future thinking differently tax cognitive resources.

During the past 20 years involuntary memories have been established as a noteworthy phenomenon, which occur spontaneously in everyday life and with greater frequency than expected. Other types of ideations also occur involuntarily and very frequently, both in the normal population and in clinical groups. The aim of this paper was to assess for the first time whether involuntary memories and involuntary future thoughts differ in the amount of cognitive resources, considering that both are experienced as being rather automatic. As in previous work on mind wandering, this was done by assessing the effect of different conditions on frequency of spontaneous thoughts about past and future. Involuntary memories and future thoughts were obtained in an experimental setting (vigilance task) that mimics a mind-wandering task. In it, participants saw slides (trials) with horizontal or vertical (target) lines. In half or one-fourth of the trials verbal cues were also presented. In a third condition one-fourth of the trials had verbal cues and one-fourth had simple arithmetic calculations. Participants were asked to report any mental content that crosses their mind when the vigilance task stopped. Results show that the manipulation modulates the number of both involuntary memories and future thoughts, and both engage cognitive resources. Future involuntary thoughts seem to require more cognitive effort than involuntary memories and, specifically, future scenarios require more cognitive resources than both involuntary memories and future plans. The results support previous findings showing that reporting spontaneous mental contents makes use of cognitive resources and are discussed linking the involuntary memory literature with mind wandering and metacognitive processes.

Defending and reducing belief in memories: An experimental laboratory analogue.

When receiving disconfirmatory social feedback about recollected events, people sometimes defend and sometimes reduce their belief that the event genuinely occurred. To improve estimates of the rates of memory defense and reduction, and of the magnitude of the change in belief in occurrence that results, in the present studies we examined the effect of disconfirmatory social challenges made to correctly recalled memories for actions performed in the lab. Adult participants performed, imagined, or heard action statements and imagined some of the initial actions multiple times. One week later, they completed a source-monitoring test and rated the actions on belief in their occurrence, recollection, visual detail, vividness, and reexperiencing. Four of the correctly recalled performed actions were challenged either prior to making the ratings during the test (Study 1, N = 44) or after making initial ratings after completing the test, following which the ratings were taken again (Study 2, N = 85). Across both studies, challenges were associated with lower belief-in-occurrence and recollection ratings on average than for control items, and belief in occurrence was affected to a greater extent than recollective features. Challenges that occurred during the test produced more instances of defense, whereas challenges that occurred after the test produced more instances of reduction. A closer analysis showed that some participants always defended, some always reduced, and some both defended and reduced belief. Responses to the first challenge positively predicted the responses to subsequent challenges. In addition, the procedure in Study 2 produced a variety of types of nonbelieved memories.

Sub-types of nonbelieved memories reveal differential outcomes of challenges to memories.

Nonbelieved memories (NBMs) highlight the independence between distinct metamemorial judgements that contribute to the experience of remembering. Initial definitions of NBMs portrayed them as involving the withdrawal of belief in occurrence despite sustained recollection. While people rate belief for their NBMs as weaker than recollection, the average difference is too small to support the idea that autobiographical belief is completely withdrawn in all cases. Furthermore, autobiographical belief and recollection ratings vary considerably across NBMs. In two studies, we reanalysed data from prior studies to examine whether NBM reports reflect a single category or multiple sub-categories using cluster analytic methods. In Study 1, we identified three sub-types of NBMs. In Study 2 we incorporated the concept of belief in accuracy, and found that two of the clusters from Study 1 split into two clusters apiece. All clusters were characterised by higher recollection than belief in occurrence ratings, and clusters were differentiated by the degree of difference between these variables. In both studies the clusters were discriminated by a number of memory characteristic ratings and by reasons reported as leading to the alteration of belief. Implications for understanding the remembering of past events and predicting the creation of NBMs are discussed.

Visual object imagery and autobiographical memory: Object Imagers are better at remembering their personal past.

In the present study we examined whether higher levels of object imagery, a stable characteristic that reflects the ability and preference in generating pictorial mental images of objects, facilitate involuntary and voluntary retrieval of autobiographical memories (ABMs). Individuals with high (High-OI) and low (Low-OI) levels of object imagery were asked to perform an involuntary and a voluntary ABM task in the laboratory. Results showed that High-OI participants generated more involuntary and voluntary ABMs than Low-OI, with faster retrieval times. High-OI also reported more detailed memories compared to Low-OI and retrieved memories as visual images. Theoretical implications of these findings for research on voluntary and involuntary ABMs are discussed.

Why are we not flooded by involuntary autobiographical memories? Few cues are more effective than many.

Recent research on involuntary autobiographical memories (IAMs) has shown that these memories can be elicited and studied in the laboratory under controlled conditions. Employing a modified version of a vigilance task developed by Schlagman and Kvavilashvili (Mem Cogn 36:920-932, 2008) to elicit IAMs, we investigated the effects of varying the frequency of external cues on the number of IAMs reported. During the vigilance task, participants had to detect an occasional target stimulus (vertical lines) in a constant stream of non-target stimuli (horizontal lines). Participants had to interrupt the task whenever they became aware of any task-unrelated mental contents and to report them. In addition to line patterns, participants were exposed to verbal cues and their frequency was experimentally manipulated in three conditions (frequent cues vs. infrequent cues vs. infrequent cues plus arithmetic operations). We found that, compared to infrequent cues, both conditions with frequent cues and infrequent cues plus arithmetic operations decreased the number of IAMs reported. The comparison between the three experimental conditions suggests that this reduction was due to the greater cognitive load in conditions of frequent cues and infrequent cue plus arithmetic operations. Possible mechanisms involved in this effect and their implications for research on IAMs are discussed.

Reasons for withdrawing belief in vivid autobiographical memories.

Previous studies have shown that many people hold personal memories for events that they no longer believe occurred. This study examines the reasons that people provide for choosing to reduce autobiographical belief in vividly recollected autobiographical memories. A body of non-believed memories provided by 374 individuals was reviewed to develop a qualitatively derived categorisation system. The final scheme consisted of 8 major categories (in descending order of mention): social feedback, event plausibility, alternative attributions, general memory beliefs, internal event features, consistency with external evidence, views of self/others, personal motivation and numerous sub-categories. Independent raters coded the reports and judged the primary reason that each person provided for withdrawing belief. The nature of each category, frequency of category endorsement, category overlap and phenomenological ratings are presented, following which links to related literature and implications are discussed. This study documents that a wide variety of recollective and non-recollective sources of information influence decision-making about the occurrence of autobiographical events.

Inhibitory effects of thought substitution in the think/no-think task: evidence from independent cues.

When people try not to think about a certain item, they can accomplish this goal by using a thought substitution strategy and think about something else. Research conducted with the think/no-think (TNT) paradigm indicates that such strategy leads subsequently to forgetting the information participants tried not to think about. The present study pursued two goals. First, it investigated the mechanism of forgetting due to thought substitution, contrasting the hypothesis by which forgetting is due to blocking caused by substitutes with the hypothesis that forgetting is due to inhibition (using an independent cue methodology). Second, a boundary condition for forgetting due to thought substitution was examined by creating conditions under which the generation of appropriate substitutes would be impaired. In two experiments, participants completed a TNT task under thought substitution instructions in which either words or pseudo-words were used as original cues and memory was assessed with original and independent cues. The results revealed forgetting in both original and independent cue tests, supporting the inhibitory account of thought substitution, but only when cues were words, and not when they were non-words, pointing to the ineffectiveness of a thought substitution strategy when original cues lack semantic content.

Manipulating cues in involuntary autobiographical memory: verbal cues are more effective than pictorial cues.

In two experiments, pictorial cues were compared with their verbal labels to assess their effectiveness in eliciting involuntary autobiographical memories. Cues were relatively complex in Experiment 1 (e.g., relaxing on a beach) and simple objects in Experiment 2 (e.g., a ball). In both experiments, participants went through a vigilance task in which they were presented with frequent nontarget and rare target visual stimuli. Pictures or their corresponding verbal labels were also displayed on both target and nontarget stimuli, but participants were told that these were irrelevant to the task. They were asked to interrupt the vigilance task whenever they became aware of task-unrelated mental contents and to report them. In both experiments, more involuntary memories were elicited in the verbal cue condition, rather than in the pictorial cue condition. This result is discussed in relation to previous work that highlighted the greater effectiveness of verbal cues in memory tasks.

Explicit and implicit memory for the QWERTY keyboard: the role of motor simulation and deictic gestures.

In three experiments, we investigated explicit and implicit knowledge about the location of letters on the QWERTY keyboard in young students, and the mechanisms involved. Participants completed a verbal report task in which they were asked to locate the 21 letters of the Italian alphabet on a blank QWERTY keyboard (explicit memory). Subsequently, they carried out a motor production task, i.e., typing letters on a blank keyboard (implicit memory). Consistent with previous studies and several theories emphasizing the importance of implicit knowledge in typing, results showed that explicit knowledge about the QWERTY keyboard is systematically worse than procedural knowledge (Experiment 1). These two types of knowledge, however, are related. Second, we showed that explicit memory for letter position was affected when participants were engaged in a secondary task that required hands/arms movements. Specifically, loading participants' sensorimotor resources led to a decrease in explicit memory performance when the secondary task required hand/arm movements (hand/arms tapping) compared to when it required legs-feet movements (control condition). This result suggests that explicit knowledge is modulated by sensorimotor simulation (Experiment 2). Third, compared to a purely verbal response, pointing to the key on the keyboard did not improve explicit memory accuracy (Experiment 3). Taken together, the results indicate that sensorimotor simulation, and not just gestures, modulates the accessibility to explicit mental representations of verbal/spatial material, like letters on a keyboard.

Semantic and episodic processes differently predict false memories in the DRM task.

There is a fervent debate about the processes underpinning false memories formation. Seminal theories have suggested that semantic memory would be involved in false memories production, while episodic memory would counter their formation. Yet, direct evidence corroborating such view is still lacking. Here, we tested this possibility by asking participants to perform the Deese-Roediger-McDermott (DRM) task, a typical false memory paradigm, in which they had to study lists of words and subsequently to recognize and distinguish them from new words (i.e., the false memory items). The same participants were also required to perform a semantic task and an episodic-source memory task. Our results showed that a higher number of false memories in the DRM task occurred for those participants with better semantic memory abilities, while a lower number of false memories occurred for participants with better episodic abilities. These findings support a key role of semantic processes in false memory formation and, more generally, help clarify the specific contribution of different memory systems to false recognitions.

Enhancing mental health and well-being in adults from lower-resource settings: A mixed-method evaluation of the impact of problem management plus.

Mental health conditions, recognised as a global crisis, were further exacerbated by the COVID-19 pandemic. Access to mental health services remains limited, particularly in low-income regions. Task-sharing interventions, exemplified by Problem Management Plus (PM+), have emerged as potential solutions to bridge this treatment gap. This study presents an evaluation of the PM+ scale-up in Sub-Saharan Africa (Ethiopia and Benin) and Eastern Europe (Croatia and Bosnia and Herzegovina) as part of a mental health and psychosocial support programming including 87 adult participants. A mixed-method approach assesses the impact of the intervention. Quantitative analyses reveal significant reductions in self-reported problems, depression, anxiety and improved functioning. Qualitative data highlight four main themes: general health, family relationships, psychosocial problems and daily activities. These thematic areas demonstrate consistent improvements across clients, irrespective of the region. The findings underscore the impact of PM+ in addressing a broad spectrum of client issues, demonstrating its potential as a valuable tool for mitigating mental health challenges in diverse settings. This study contributes to the burgeoning body of evidence supporting PM+ and highlights its promise in enhancing mental health outcomes on a global scale, particularly for vulnerable populations.