Remote Autobiographical Memories Research Articles

A Comparison of Single- and Multi-Echo Processing of Functional MRI Data During Overt Autobiographical Recall.

Recent years have seen an increase in the use of multi-echo fMRI designs by cognitive neuroscientists. Acquiring multiple echoes allows one to increase contrast-to-noise; reduce signal dropout and thermal noise; and identify nuisance signal components in BOLD data. At the same time, multi-echo acquisitions increase data processing complexity and may incur a cost to the temporal and spatial resolution of the acquired data. Here, we re-examine a multi-echo dataset previously analyzed using multi-echo independent components analysis (ME-ICA) and focused on hippocampal activity during the overtly spoken recall of recent and remote autobiographical memories. The goal of the present series of analyses was to determine if ME-ICA’s theoretical denoising benefits might lead to a practical difference in the overall conclusions reached. Compared to single-echo (SE) data, ME-ICA led to qualitatively different findings regarding hippocampal contributions to autobiographical recall: whereas the SE analysis largely failed to reveal hippocampal activity relative to an active baseline, ME-ICA results supported predictions of the Standard Model of Consolidation and a time limited hippocampal involvement. These data provide a practical example of the benefits multi-echo denoising in a naturalistic memory paradigm and demonstrate how they can be used to address long-standing theoretical questions.

Long-lasting memory no longer means forever: Relationship between accelerated long-term forgetting and autobiographical memory disorders amongst patients with temporal lobe epilepsy

Patients with temporal lobe epilepsy (TLE) have difficulties when they are asked to recall remote autobiographical memory. Also, some patients with epilepsy show accelerated long-term forgetting (ALF) over days or weeks for material demonstrated to have been retained when assessed after typical short-term delays. When remote autobiographical memory has been investigated in patients who show ALF, impairments have been detected in most cases, but the extent to which remote autobiographical memory impairments are explained by early consolidation deficits has not been clarified.

The relationship between hippocampal subfield volumes and autobiographical memory persistence.

Structural integrity of the human hippocampus is widely acknowledged to be necessary for the successful encoding and retrieval of autobiographical memories. However, evidence for an association between hippocampal volume and the ability to recall such memories in healthy individuals is mixed. Here we examined this issue further by combining two approaches. First, we focused on the anatomically distinct subregions of the hippocampus where more nuanced associations may be expressed compared to considering the whole hippocampal volume. A manual segmentation protocol of hippocampal subregions allowed us to separately calculate the volumes of the dentate gyrus/CA4, CA3/2, CA1, subiculum, pre/parasubiculum and uncus. Second, a critical feature of autobiographical memories is that they can span long time periods, and so we sought to consider how memory details persist over time by conducting a longitudinal study whereby participants had to recall the same autobiographical memories on two visits spaced 8 months apart. Overall, we found that there was no difference in the total number of internal (episodic) details produced at Visits 1 and 2. However, further probing of detail subcategories revealed that specifically the amount of subjective thoughts and emotions included during recall had declined significantly by the second visit. We also observed a strong correlation between left pre/parasubiculum volume and the amount of autobiographical memory internal details produced over time. This positive relationship was evident for particular facets of the memories, with remembered events, perceptual observations and thoughts and emotions benefitting from greater volume of the left pre/parasubiculum. These preliminary findings expand upon existing functional neuroimaging evidence by highlighting a potential link between left pre/parasubiculum volume and autobiographical memory. A larger pre/parasubiculum appears not only to protect against memory decay, but may possibly enhance memory persistence, inviting further scrutiny of the role of this brain region in remote autobiographical memory retrieval.

Eye movements of recent and remote autobiographical memories: fewer and longer lasting fixations during the retrieval of childhood memories

There is an increased interest in the study of eye movements during the retrieval of autobiographical memories. Following this trend, the aim of the current study was to evaluate eye movements during the retrieval of remote and recent autobiographical memories. We instructed 71 participants to retrieve memories of personal events from early childhood (6-10years), late childhood/early adolescence (11-14years), late adolescence (15-18years), and the last month. During the retrieval of these memories, participants wore eye-tracking glasses. Analyses showed that early childhood memories triggered fewer fixations and fixations with longer durations than memories from the last month. However, no significant differences were observed for the number of saccades, saccade durations, or total amplitude of the saccades. The fewer and longer lasting fixations during the retrieval of early childhood memories can be attributed either to the visual system reconstructing remote memories from an observer perspective or to difficulties when reconstructing remote memories.

Smell your memories: Positive effect of odor exposure on recent and remote autobiographical memories in Alzheimer’s disease

ABSTRACTIntroduction: There is a burgeoning interest in the effects of odor exposure on autobiographical memory in Alzheimer’s disease (AD). We pursued this line of research by assessing the effect of odor exposure on the retrieval of recent and remote memories in AD.Method: Twenty-six patients with mild AD and 28 controls were tested in two conditions: with and without odor exposure. In each condition, participants were invited to retrieve two childhood memories, two adulthood memories, and two recent memories.Results: Analysis showed that AD patients produced a higher number of and more specific childhood memories, adulthood memories, and recent memories after odor exposure than without odor.Discussion: These findings demonstrate how odor exposure may alleviate anterograde and retrograde amnesia, at least when considering the ability of patients with mild AD to retrieve few recent or remote memories.

The life span distribution of autobiographical memory in Alzheimer's disease.

The literature on the temporal distribution of autobiographical memory in Alzheimer's disease (AD) is characterized by mixed findings concerning the presence of a temporal gradient in the loss of autobiographical memory. Some studies show a gradient, implying better access to more remote autobiographical memories, whereas others do not. These conflicting results likely reflect differences in the test methodologies, accentuating the need for replications and extensions. Forty-five older adults diagnosed with AD (via Mini-Mental State Examination, M = 19.89, SD = 4.05) and a matched sample of 44 healthy older adults were assessed on two different autobiographical memory measures: the Autobiographical Memory Interview (Kopelman, Wilson, & Baddeley, 1990) and the Galton-Crovitz task (word and object cueing) to examine the temporal distribution of personal autobiographical memories across the life span. The impairment of episodic and personal semantic remembering, as indexed by the Autobiographical Memory Interview, was associated with a negative temporal gradient with better preservation of memories from the remote past, relative to the recent one. The results from the word- and object-cueing task replicated the finding that AD is associated with markedly impaired recall of recent events. In addition, both groups showed a peak in the recollection of events from middle childhood and adolescence, consistent with research on the reminiscence bump. Older adults diagnosed with AD demonstrate increased recollection of personal semantic and episodic events from the remote past relative to the recent one. The findings are discussed in relation to prominent models of memory consolidation. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Evolution of autobiographical memory impairments in Alzheimer's disease and frontotemporal dementia – A longitudinal neuroimaging study

Compromised autobiographical memory (ABM) retrieval is well established in dementia, attributable to degeneration of a core memory brain network. It remains unclear, however, how the progressive spread of atrophy with advancing disease severity impacts ABM retrieval across life epochs. To this end, we conducted a longitudinal study of recent and remote ABM in Alzheimer's disease (AD, n =11), and a frontotemporal lobar degeneration group (FTD, n =13) comprising 7 behavioral variant FTD and 6 semantic dementia patients, in comparison with 23 healthy older Controls. Patients were re-assessed approximately one year following their initial visit and underwent repeat testing and brain imaging. Linear mixed modeling neuroimaging analyses explored disease-specific cortical changes driving ABM alterations over time. AD patients showed comparable ABM profiles across assessment periods however, follow-up performance correlated strongly with lateral temporal lobe integrity. In contrast, recent ABMs were disproportionately disrupted at follow-up relative to baseline in the FTD group, attributable to cortical thinning in posterior brain regions, including the right posterior cingulate cortex. Our findings offer new insights regarding the potential time-specific role of discrete cortical regions in ABM retrieval and the differential fate of formerly evocative memories with advancing disease severity in dementia syndromes.

The effect of cortisol on autobiographical memory retrieval depends on remoteness and valence of memories

There is evidence that specificity of autobiographical memory (AM) retrieval is impaired by cortisol. However, it is unknown whether glucocorticoids differentially influence the retrieval of recent versus remote AMs. Therefore, the aim of the current study was to investigate the effects of cortisol on AM retrieval, in terms of memory specificity, with respect to remoteness of the retrieved memories. A placebo controlled, double blind study was conducted. Thirty female and 24 male healthy participants (mean age 24.5, SD=3.7) received either placebo or 10mg hydrocortisone before completing an autobiographical memory test. Participants showed higher memory specificity for recent memories compared to remote ones. There was no main effect of cortisol on AM retrieval. However, interaction effects suggest that cortisol affects remote, but not recent memories, which seems to depend upon valence.

Brain structural, functional, and cognitive correlates of recent versus remote autobiographical memories in amnestic Mild Cognitive Impairment.

Deficits in autobiographical memory appear earlier for recent than for remote life periods over the course of Alzheimer's disease (AD). The present study aims to further our understanding of this graded effect by investigating the cognitive and neural substrates of recent versus remote autobiographical memories in patients with amnestic Mild Cognitive Impairment (aMCI) thanks to an autobiographical fluency task. 20 aMCI patients and 25 Healthy elderly Controls (HC) underwent neuropsychological tests assessing remote (20-to-30 years old) and recent (the ten last years) autobiographical memory as well as episodic and semantic memory, executive function and global cognition. All patients also had a structural MRI and an FDG-PET scan. Correlations were assessed between each autobiographical memory score and the other tests as well as grey matter volume and metabolism. Within the aMCI, performances for the remote period correlated with personal semantic memory and episodic memory retrieval whereas performances for the recent period only correlated with episodic memory retrieval. Neuroimaging analyses revealed significant correlations between performances for the remote period and temporal pole and temporo-parietal cortex volumes and anterior cingulate gyrus metabolism, while performances for the recent period correlated with hippocampal volume and posterior cingulate, medial prefrontal and hippocampus metabolism. The brain regions related with the retrieval of events from the recent period showed greater atrophy/hypometabolism in aMCI patients compared to HC than those involved in remote memories. Recall of recent memories essentially relies on episodic memory processes and brain network while remote memories also involve other processes such as semantic memory. This is consistent with the semanticization of memories with time and may explain the better resistance of remote memory in AD.

Grey and white matter correlates of recent and remote autobiographical memory retrieval--insights from the dementias.

The capacity to remember self-referential past events relies on the integrity of a distributed neural network. Controversy exists, however, regarding the involvement of specific brain structures for the retrieval of recently experienced versus more distant events. Here, we explored how characteristic patterns of atrophy in neurodegenerative disorders differentially disrupt remote versus recent autobiographical memory. Eleven behavioural-variant frontotemporal dementia, 10 semantic dementia, 15 Alzheimer's disease patients and 14 healthy older Controls completed the Autobiographical Interview. All patient groups displayed significant remote memory impairments relative to Controls. Similarly, recent period retrieval was significantly compromised in behavioural-variant frontotemporal dementia and Alzheimer's disease, yet semantic dementia patients scored in line with Controls. Voxel-based morphometry and diffusion tensor imaging analyses, for all participants combined, were conducted to investigate grey and white matter correlates of remote and recent autobiographical memory retrieval. Neural correlates common to both recent and remote time periods were identified, including the hippocampus, medial prefrontal, and frontopolar cortices, and the forceps minor and left hippocampal portion of the cingulum bundle. Regions exclusively implicated in each time period were also identified. The integrity of the anterior temporal cortices was related to the retrieval of remote memories, whereas the posterior cingulate cortex emerged as a structure significantly associated with recent autobiographical memory retrieval. This study represents the first investigation of the grey and white matter correlates of remote and recent autobiographical memory retrieval in neurodegenerative disorders. Our findings demonstrate the importance of core brain structures, including the medial prefrontal cortex and hippocampus, irrespective of time period, and point towards the contribution of discrete regions in mediating successful retrieval of distant versus recently experienced events.

Remoteness Modulates the Effects of Emotional Valence on the Neural Network of Autobiographical Memory in Older Females

To better understand the effects of emotional valence on autobiographical memory (AM), the present study compared behavioral performance and neural activation in positive and negative AMs at different levels of remoteness (the time-interval between encoding and retrieving) in a sample of Chinese older females. The behavioral results revealed that older females held a positivity bias in emotional AM in the form of an obvious trend of higher level of vividness when retrieving positive AMs compared with negative AMs. At the neural level, a de-lateralized neural network, covering the core AM system and the affect processing system, was found to be associated with emotional AM. Within the network, increased activation of a prefrontal cortex/anterior cingulate cortex (PFC/ACC) control system was found when processing negative recent AMs compared with positive recent AMs; increased activation of the somatosensory area was found with positive remote AMs compared with negative remote AMs. On the basis of these results, we suggest that the positivity bias of the older adults in recent AMs may be due to the use of an emotion regulation or control system (involving PFC/ACC) against negative AMs; in contrast, for remote AMs, the positivity bias may be due to better access to the positive remote memory details than the negative remote memory details.

FUNCTIONAL SUB-SPECIALIZATION OF THE RETROSPLENIAL CORTEX IN SPATIAL COGNITION PROCESSES USING ALE META-ANALYSIS

cognitive correlates of recent versus remote autobiographical memories in the pre-dementia stage of Alzheimer’s disease (AD). Methods: 20 MCI patients underwent an autobiographical memory test assessing remote (when the patients were 20 to 30 years old) and recent (ten last years) memories. All patients also had a 3T T1 structural MRI and an FDGPET scan, as well as neuropsychological tests assessing semantic autobiographical memory, verbal episodic memory and global cognitive functioning (Mattis). Correlations were then assessed between each of the two autobiographical memory scores and grey matter volume, metabolism and cognitive performances. Results: The score for the remote period correlated with semantic autobiographical memory, verbal episodic memory retrieval and as a trend for the Mattis, whereas the recent period only correlated with verbal episodic memory retrieval. Neuroimaging analyses revealed significant correlations between the remote period and temporal pole and temporo-parietal cortex volume as well as anterior cingulate gyrus metabolism, while the recent period correlated with hippocampus volume and metabolism in the posterior cingulate, medial prefrontal and hippocampal areas. The brain regions related with the recent period showed greater atrophy/hypometabolism in MCI patients compared to controls than those involved in remote memories. Conclusions: The cognitive and neural substrates of recent memories both point to the involvement of relatively pure episodic memory processes involving episodic memory network brain areas. By contrast, remote memories seem to involve other processes and brain regions as well, such as semantic memory processes, consistent with the idea that remote memories tend to semantize with time. The distinct cognitive and cerebral substrates of autobiographical memories according to life periods could explain the differential impairment of recent and remote memories observed in the early stage of AD.

BRAIN STRUCTURAL, FUNCTIONAL, AND COGNITIVE CORRELATES OF RECENT VERSUS REMOTE AUTOBIOGRAPHICAL MEMORIES IN MILD COGNITIVE IMPAIRMENT

article i nfo Deficits in autobiographical memory appear earlier for recent than for remote life periods over the course of Alzheimer3sdisease(AD).Thepresentstudyaimstofurtherourunderstandingof thisgradedeffectbyinvestigat- ing the cognitive and neural substrates of recent versus remote autobiographical memories in patients with amnestic Mild Cognitive Impairment (aMCI) thanks to an autobiographical fluency task. 20 aMCI patients and 25 Healthy elderly Controls (HC) underwent neuropsychological tests assessing remote (20-to-30 years old) and recent (the ten last years) autobiographical memory as well as episodic and semantic memory, executive function and global cognition. All patients also had a structural MRI and an FDG-PET scan. Correlations were assessed between each autobiographical memory score and the other tests as well as grey matter volume and metabolism. Within the aMCI, performances for the remote period correlated with personal semantic memory and episodic memory retrieval whereas performances for the recent period only correlated with episodic mem- ory retrieval. Neuroimaging analyses revealed significant correlations between performances for the remote pe- riod and temporal pole and temporo-parietal cortex volumes and anterior cingulate gyrus metabolism, while performancesfortherecentperiodcorrelatedwithhippocampalvolumeandposteriorcingulate,medialprefron- tal and hippocampus metabolism. The brain regions related with the retrieval of events from the recent period showed greater atrophy/hypometabolisminaMCIpatients comparedtoHCthan those involvedinremote mem- ories.Recallofrecentmemoriesessentiallyreliesonepisodicmemory processesandbrainnetworkwhileremote memories also involve other processes such as semantic memory. This is consistent with the semanticization of

Autobiographical memory in semantic dementia: New insights from two patients using fMRI

Episodic autobiographical memory (EAM) consists of personal events embedded within a specific spatiotemporal context. Patients with semantic dementia (SD) generally show preserved recent EAMs, but a controversy remains concerning their ability to retrieve remote ones. Only one fMRI study examined remote autobiographical memory in SD through a longitudinal case study (Maguire, Kumaran, Hassabis, & Kopelman, 2010). Here, we propose a cross-sectional study to test the hippocampo-neocortical up-regulation hypothesis, through a multimodal approach (gray matter volume, activation, connectivity analyses), directly comparing recent and remote autobiographical memory retrieval and collecting data to asses phenomelogical re-experiencing. EAM retrieval recruits a distributed network of brain regions, notably the hippocampus which is shown to be atrophied in SD, although some studies report no hippocampal atrophy in SD. Using fMRI, we examined recent and remote EAM retrieval in two SD patients with different profiles of hippocampal atrophy, compared to 12 healthy elders (HE). JPL presented severe bilateral hippocampal atrophy, while EP showed sparing of both hippocampi. Behaviourally, JPL was impaired at retrieving EAMs from both life periods and showed poorer use of visual mental imagery than HE, while EP retrieved memories which were as episodic as those of HE for both periods and relied on greater use of visual mental imagery than HE. Neuroimaging results showed that, for JPL, hyperactivations of the residual hippocampal tissue and of frontal, lateral temporal, occipital and parietal cortices did not efficiently compensate his autobiographical memory deficit. EP however presented hyperactivations in similar neocortical regions which appeared to be more efficient in compensating for atrophy elsewhere, since EP's EAM retrieval was preserved. Functional connectivity analyses focusing on the hippocampus showed how the residual hippocampal activity was connected to other brain areas. For JPL, recent autobiographical retrieval was associated with connectivity between the posterior hippocampus and middle occipital gyrus, while for EP, connectivity was detected between the anterior hippocampus and numerous regions (medial temporal, occipital, temporal, frontal, parietal) for both recent and remote periods. These findings suggest that intensification of hippocampal atrophy in SD strongly affects both recent and remote autobiographical recollection. Up-regulation of neocortical regions and functional hippocampal–neocortical connectivity within the autobiographical network may be insufficient to compensate the lifelong episodic memory deficit for patients with extensive hippocampal atrophy.

Same as it ever was: Vividness modulates the similarities and differences between the neural networks that support retrieving remote and recent autobiographical memories

The comparison of recent and remote autobiographical memories is often confounded by qualitative disparities across memories of different ages, such as vividness. In this study, ten individuals prospectively collected audio recordings that were used to cue memories of recent (~1month old) and remote (~1.5year old) everyday events. Because the retrieval cues were recorded at the time of event, they were highly potent. Although remote events did not differ in novelty, importance, or emotional change at the time at the time of encoding, half of the cues for these events induced retrieval comparable in vividness to recent events (all of which were vividly re-experienced). Recent and remote vivid memories were associated with a neural pattern that included right frontal, left parietal and limbic regions that were active early in the retrieval period. Non-vivid remote memories were associated with a later onset of a bilateral distributed pattern that included regions in the frontal, parietal, and temporal lobes. Functional connectivity analysis indicated that the left anterior hippocampus was co-activated with bilateral frontal, parahippocampal, and parietal regions for vivid memories (irrespective of memory age) early in the retrieval period, whereas non-vivid memories, alongside recent memories, showed later and broader co-activation with frontal, parietal, occipital, and temporal regions. The absence of a significant difference between the recent and remote vivid memories may be due to insufficient power to detect potential subtle differences between these conditions. Nonetheless, there was evidence for different patterns of hippocampal–neocortical connectivity for remote memories and recent memories, irrespective of vividness. These findings suggest that while there is a functional shift in hippocampal connectivity that is associated with memory age when very recent events are used, vividness is strongly associated with both activation and functional connectivity patterns irrespective of memory age.

Representations of recent and remote autobiographical memories in hippocampal subfields.

The hippocampus has long been implicated in supporting autobiographical memories, but little is known about how they are instantiated in hippocampal subfields. Using high-resolution functional magnetic resonance imaging (fMRI) combined with multivoxel pattern analysis we found that it was possible to detect representations of specific autobiographical memories in individual hippocampal subfields. Moreover, while subfields in the anterior hippocampus contained information about both recent (2 weeks old) and remote (10 years old) autobiographical memories, posterior CA3 and DG only contained information about the remote memories. Thus, the hippocampal subfields are differentially involved in the representation of recent and remote autobiographical memories during vivid recall. © 2013 The Authors. Hippocampus Published by Wiley Periodicals, Inc.

Detecting Representations of Recent and Remote Autobiographical Memories in vmPFC and Hippocampus

How autobiographical memories are represented in the human brain and whether this changes with time are questions central to memory neuroscience. Two regions in particular have been consistently implicated, the ventromedial prefrontal cortex (vmPFC) and the hippocampus, although their precise contributions are still contested. The key question in this debate, when reduced to its simplest form, concerns where information about specific autobiographical memories is located. Here, we availed ourselves of the opportunity afforded by multivoxel pattern analysis to provide an alternative to conventional neuropsychological and fMRI approaches, by detecting representations of individual autobiographical memories in patterns of fMRI activity. We examined whether information about specific recent (two weeks old) and remote (10 years old) autobiographical memories was represented in vmPFC and hippocampus, and other medial temporal and neocortical regions. vmPFC contained information about recent and remote autobiographical memories, although remote memories were more readily detected there, indicating that consolidation or a change of some kind had occurred. Information about both types of memory was also present in the hippocampus, suggesting it plays a role in the retrieval of vivid autobiographical memories regardless of remoteness. Interestingly, we also found that while recent and remote memories were both represented within anterior and posterior hippocampus, the latter nevertheless contained more information about remote memories. Thus, like vmPFC, the hippocampus too respected the distinction between recent and remote memories. Overall, these findings clarify and extend our view of vmPFC and hippocampus while also informing systems-level consolidation and providing clear targets for future studies.

Odour-induced mental time travel into the past and future: Do odour cues retain a unique link to our distant past?

Proustian memories, or memories spontaneously evoked by taste and odours, have been argued to be uniquely linked to our remote past. This view suggests an asymmetry between odour-cued memories and odour-cued representations of future events regarding their temporal distance to the present. We investigated the temporal distribution and other phenomenological qualities of autobiographical memories and future events employing a 2 (temporal direction: past vs future)×3 (cue type: verbal, visual, and odour) mixed design. We found that while odour-evoked memories were predominantly from the first decade of life, the future condition showed a marked preponderance of odour-cued events in the upcoming year. Odour-evoked memories were also less specific than the verbal and visual conditions. The odour condition was responsible for interactions concerning coherency of the events and the events’ significance to the life story. The results support the view that odours possess a unique ability to evoke remote autobiographical memories.

Prefrontal cortex recruitment during naturalistic remote memory: A factorial block-event fMRI study

Most classical neuroimaging studies of human memory require the subject to follow task instructions, discriminate stimuli, make a decision and, finally, press a button to respond. To which extent does such a cognitive sequence influence neural correlates of recognition memory especially with respect to the prefrontal cortex (PFC) is not clear yet. We set up a naturalistic recognition task. Personal photographs were mixed with photographs from family albums of people who were not known to the participant. The subjects alternated a recognition task (recognition and response) with a mere observational one (simple recognition). This factorial block-event functional MRI design allowed us to disentangle the regions related to memory (personal photographs vs. distracters under both conditions) from those related to the response (responding vs. observing) as well as to examine the interaction between the two factors. Only medial and left orbito-frontal regions were transiently active during successful recognition in the two task conditions. Memory and responding interacted in the left lateral PFC within the middle and inferior gyrus. These regions were more active for personal photographs than for distracters only when the subject had to respond. Sustained activations spread bilaterally whatever the task. Such a design that encompasses personal photographs, an observation period for recognition as well as a mixed-design may have led to a better isolation of the neural network underlying remote autobiographical memory. Recruitment within the PFC during retrieval was only limited to its medial and left anterior parts. Sustained activation did not differ between the discrimination and the observation period. This original design might be valuable for further dissociation between decision, self, autobiographical memory and the PFC.

Remembering all that and then some: Recollection of autobiographical memories after a 1-year delay

We have previously shown that repeated retrievals of remote autobiographical memories over the course of one month led to an overall increase in reported detail (Nadel, Campbell, & Ryan, 2007). The current study examined the retrieval of those same memories 1 year later in order to determine whether the level of detail remained stable or whether the memories returned to their original state. Participants reported even more details than they had recalled at least 1 year earlier, including new details that were reported for the first time. This finding was consistent across both multiple and single retrieval conditions, suggesting that the critical factor leading to the increase in recall was the passage of time. These findings provide evidence for long-term effects of repeated retrieval on memory content.