Item Memory Research Articles

Differential effects of negative valence and memory type on accuracy, confidence, and metacognitive efficiency

Emotion enhances the subjective experience of recollection. Previous research examined associations between memory accuracy and metamemory confidence judgments, but these studies have not quantified the relationship between accuracy and metacognitive confidence judgments. In this study we utilize signal detection theory frameworks to investigate how memory accuracy (measured by discrimination sensitivity) and the alignment between metamemory confidence judgments and memory accuracy (ie. metacognitive efficiency) varies for neutral and negative valence, as well as item and associative detail memory types. Our results indicate that valence and memory type have different effects on accuracy, confidence, and metacognitive efficiency. Negative valence was associated with enhanced accuracy for both items and associated details, but its relationship with response bias varied across memory types, with conservative recognition responses observed for items and liberal responses for associative details. We also observed a double dissociation between metamemory confidence judgements across valence and memory type with negative valence associated with increased confidence for item memory, but decreased confidence for associated details. Examining the association between memory accuracy and metamemory confidence revealed that metacognitive efficiency was greater for negatively valenced items compared to neutral, but this effect did not generalize to details associated with negatively valenced items. These findings advance our understanding of how arousing, negatively valenced information modulates memory and metacognition.

Integrative multi-omics analysis reveals the role of tumor-associated endothelial cells and their signature in prognosis of intrahepatic cholangiocarcinoma

This study aims to investigate the interplay between tumor-associated endothelial cells (TECs) and immune cells within the tumor microenvironment (TME) and its impact on tumor prognosis. We conducted single-cell RNA sequencing (scRNA-seq) of tumor, normal, and lymph node tissues obtained from intrahepatic cholangiocarcinoma (ICC) patients to reveal the role of TECs in tumor angiogenesis and their significant heterogeneity. Meanwhile, we identified genes highly expressed in TECs and constructed TEC signatures (TEC.Sig). Next, we calculated TEC scores of samples based on TEC.Sig. Patients with higher TEC scores exhibited a higher frequency of KRAS mutations, which was associated with increased infiltration of neutrophils and immature dendritic cells (iDCs), and decreased numbers of natural killer (NK), CD4 + T, and CD8 + T effector memory (Tem) cells, indicating an inflammation-dominated immunosuppressive phenotype. In contrast, BAP1 mutations and CXCL12 overexpression showed a contrasting trend. Spatial transcriptomics analysis and histological experiments further confirmed that TECs interacted with various tumor-killing immune cells through the CXCL12/CXCR4 axis. Multiple tumor immunotherapy datasets confirmed that the TEC.Sig could predict patient responses to immunotherapy. The TEC score is a promising and reliable biomarker for predicting genetic mutations and prognosis in ICC patients. Enhancing the regulation of the CXCL12/CXCR4 signaling pathway may represent a potential novel therapeutic target for ICC treatment.

Judgments of learning (JOLs) impact item memory but not source memory: Insights into JOL reactivity using a multinomial model.

Past research has evaluated participants' understanding of their memory by soliciting judgments of learning (JOLs). Importantly, JOLs sometimes change memory for the judged material, leading to JOL reactivity. The cue-strengthening account (Soderstrom et al., 2015) and changed-goal account (Mitchum et al., 2016) propose different mechanisms that lead to JOL reactivity. In the present study, we collected measures that can provide further insight into these mechanisms. Specifically, participants studied related and unrelated word pairs in different colored fonts for a source recognition test. Across three experiments, data were analyzed using a hierarchical Bayesian model of multidimensional source memory to determine how JOLs impact item memory as well as relatedness and color source memory. In Experiment 2, we also compared the effects of making JOLs to making judgments of relatedness (JORs), and Experiment 3 examined how JOLs impact study time allocation. The results of our experiments failed to fully follow predictions of either account. Making JOLs (Experiments 1-3) and JORs (Experiment 2) strengthened item memory for related as well as unrelated pairs, the latter finding not predicted by either account. In addition, JOLs and JORs did not specifically strengthen source memory for relatedness, as the cue-strengthening account predicts, nor did JOLs change study time (Experiment 3), as suggested by the changed-goal account. In all, our results provide novel insight that enhanced item memory may be largely responsible for JOL reactivity, thus adjudicating between candidate explanations. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Distinct functions for beta and alpha bursts in gating of human working memory

Multiple neural mechanisms underlying gating to working memory have been proposed with divergent results obtained in human and animal studies. Previous findings from non-human primates suggest prefrontal beta frequency bursts as a correlate of transient inhibition during selective encoding. Human studies instead suggest a similar role for sensory alpha power fluctuations. To cast light on these discrepancies we employed a sequential working memory task with distractors for human participants. In particular, we examined their whole-brain electrophysiological activity in both alpha and beta bands with the same single-trial burst analysis earlier performed on non-human primates. Our results reconcile earlier findings by demonstrating that both alpha and beta bursts in humans correlate with the filtering and control of memory items, but with region and task-specific differences between the two rhythms. Occipital beta burst patterns were selectively modulated during the transition from sensory processing to memory retention whereas prefrontal and parietal beta bursts tracked sequence order and were proactively upregulated prior to upcoming target encoding. Occipital alpha bursts instead increased during the actual presentation of unwanted sensory stimuli. Source reconstruction additionally suggested the involvement of striatal and thalamic alpha and beta. Thus, specific whole-brain burst patterns correlate with different aspects of working memory control.

Bridging big data in the ENIGMA consortium to combine non-equivalent cognitive measures

Investigators in neuroscience have turned to Big Data to address replication and reliability issues by increasing sample size. These efforts unveil new questions about how to integrate data across distinct sources and instruments. The goal of this study was to link scores across common auditory verbal learning tasks (AVLTs). This international secondary analysis aggregated multisite raw data for AVLTs across 53 studies totaling 10,505 individuals. Using the ComBat-GAM algorithm, we isolated and removed the component of memory scores associated with site effects while preserving instrumental effects. After adjustment, a continuous item response theory model used multiple memory items of varying difficulty to estimate each individual’s latent verbal learning ability on a single scale. Equivalent raw scores across AVLTs were then found by linking individuals through the ability scale. Harmonization reduced total cross-site score variance by 37% while preserving meaningful memory effects. Age had the largest impact on scores overall (− 11.4%), while race/ethnicity variable was not significant (p > 0.05). The resulting tools were validated on dually administered tests. The conversion tool is available online so researchers and clinicians can convert memory scores across instruments. This work demonstrates that global harmonization initiatives can address reproducibility challenges across the behavioral sciences.

Integrated encoding of relations and objects in visual working memory.

Comprehensive understanding of visual scenes necessitates grasping the relations among visual objects. Given the potentially pivotal role of visual working memory (VWM) in processing visual relations, it is important to investigate the representation of relations in VWM. In our previous study, we proposed the integrated storage hypothesis, postulating that relations and objects are stored together as an integrated structured representation in VWM. The present study aimed to test this hypothesis against the alternative separate encoding hypothesis by probing the irrelevant-distracting effect. Across three experiments, where participants memorized object shapes/colors while disregarding relations, an irrelevant-distracting effect was consistently observed across varying types of changes in relation and set sizes. Critically, recombining the probe with irrelevant relation from another memory item (Experiment 2) or reversing the relational roles of probed objects relative to the memory item (Experiment 3) were perceived as inconsistency with stored representations and impaired change detection. These findings supported the integrated storage hypothesis, indicating that the dynamic relations between the objects are automatically encoded alongside object identities to form an integrated structured representation. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Out-of-Distribution Detection with Memory-Augmented Variational Autoencoder

This paper proposes a novel method capable of both detecting OOD data and generating in-distribution data samples. To achieve this, a VAE model is adopted and augmented with a memory module, providing capacities for identifying OOD data and synthesising new in-distribution samples. The proposed VAE is trained on normal data and the memory stores prototypical patterns of the normal data distribution. At test time, the input is encoded by the VAE encoder; this encoding is used as a query to retrieve related memory items, which are then integrated with the input encoding and passed to the decoder for reconstruction. Normal samples reconstruct well and yield low reconstruction errors, while OOD inputs produce high reconstruction errors as their encodings get replaced by retrieved normal patterns. Prior works use memory modules for OOD detection with autoencoders, but this method leverages a VAE architecture to enable generation abilities. Experiments conducted with CIFAR-10 and MNIST datasets show that the memory-augmented VAE consistently outperforms the baseline, particularly where OOD data resembles normal patterns. This notable improvement is due to the enhanced latent space representation provided by the VAE. Overall, the memory-equipped VAE framework excels in identifying OOD and generating creative examples effectively.

Unravelling the object-based nature of visual working memory: insight from pointers.

Visual working memory (VWM) plays a crucial role in temporarily storing and processing visual information, but the nature of stored representations and their interaction with new inputs has long been unclear. The pointer system refers to how VWM links new sensory inputs to stored information using specific cues. This study aimed to investigate whether the pointer system is based on spatial, feature-based, or object-based cues by employing the repetition benefit effect, where memory performance improves with repeated memory items. Across three experiments, we manipulated spatial positions, shapes, and colors as pointer cues to determine how these features affect VWM consolidation and updating. The results showed that while spatial location serves as a strong pointer cue, shape and color features can also effectively reestablish object correspondence in VWM. These findings support the view that the pointer system in VWM is flexible and object-based, utilizing various feature cues to maintain memory continuity. This study provides new insights into how VWM connects new inputs with stored information through the pointer system.

Memory augmentation with an adaptive cognitive interface.

What we remember reflects both what we encounter, such as the intrinsic memorability of a stimulus, and our internal attentional state when we encounter that stimulus. Our memories are better for memorable images and images encountered in an engaged attentional state. Here, in an effort to modulate long-term memory performance, we manipulated these factors in combination by selecting the memorability of presented images contingent on individuals' natural fluctuations in sustained attention. Can image memorability and attentional state be strategically combined to improve memory? Are memorable images still well remembered during lapses in sustained attention, and conversely, can attentive states rescue memory performance for forgettable images? We designed a procedure to monitor participants' sustained attention dynamics on the fly via their response time fluctuations during a continuous performance task with trial-unique scene images. When high- or low-attentional states were detected, our algorithm triggered the presentation of high- or low-memorability images. Afterwards, participants completed a surprise recognition memory test for the attention-triggered images. Results demonstrated that memory performance for memorable items is not only resistant to lapses in sustained attention but also that memory cannot be further improved by encoding memorable items in engaged attentional states. On the other hand, memory performance for low-memorability images can be rescued by attentive encoding states. In sum, we show that both memorability and sustained attention can be leveraged in real time to maximize memory performance. This approach suggests that adaptive cognitive interfaces can tailor what information appears when to best support overall memory.

Intrinsic functional networks for distinct sources of error in visual working memory.

Visual working memory (VWM) is a core cognitive function wherein visual information is stored and manipulated over short periods. Response errors in VWM tasks arise from the imprecise memory of target items, swaps between targets and nontargets, and random guesses. However, it remains unclear whether these types of errors are underpinned by distinct neural networks. To answer this question, we recruited 80 healthy adults to perform delayed estimation tasks and acquired their resting-state functional magnetic resonance imaging scans. The tasks required participants to reproduce the memorized visual feature along continuous scales, which, combined with mixture distribution modeling, allowed us to estimate the measures of memory precision, swap errors, and random guesses. Intrinsic functional connectivity within and between different networks, identified using a hierarchical clustering approach, was estimated for each participant. Our analyses revealed that higher memory precision was associated with increased connectivity within a frontal-opercular network, as well as between the dorsal attention network and an angular-gyrus-cerebellar network. We also found that coupling between the frontoparietal control network and the cingulo-opercular network contributes to both memory precision and random guesses. Our findings demonstrate that distinct sources of variability in VWM performance are underpinned by different yet partially overlapping intrinsic functional networks.

The effects of prediction representations on implicit learning: evidence from sentence reading and perceptual identification

Predicting errors can facilitate implicit learning, but the long-term consequences of prediction errors are not yet fully understood. Especially when predictions are disconfirmed, it remains unclear whether initially correct prediction representations persist or are suppressed. In this study, participants first engaged in a sentence reading task and then performed a perceptual identification task after completing an N-back task or after a 24-hour delay. The perceptual identification task presented previously expected and unexpected words and previously predicted but not presented words to measure implicit memory for the critical items. This study aims to investigate the mechanisms underlying the persistence of prediction representations and the long-term effects of prediction errors on implicit learning. Our results indicate that prediction errors can promote implicit learning and can persist for more than 24 hours. Furthermore, originally correct but not seen in reality prediction representations persist to facilitate performance on the implicit memory task after 24 hours. This may reflect long-term changes in the internal representation probabilities of prediction representations.

Economic burden and quality of life of patients with dementia in China: a systematic review and meta-analysis.

China has the largest number of dementia patients worldwide. The prolonged course of dementia has a serious negative impact on the economy and quality of life of patients and their families. The purpose of this study was to conduct a systematic review and meta-analysis of the existing literature about economic burden and quality of life of people with dementia in China. Six databases were systematically searched for observational studies of the economic burden or quality of life of dementia that were published before June 30, 2024. This review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. A total of 36,411 papers were identified, and 21 studies met the inclusion criteria. The annual economic burden of dementia was 20,893 RMB (3,104 USD). The total costs associated with mild, moderate, and severe dementia were 16,619 RMB (2,469 USD), 22,283 RMB (3,311 USD), and 34,611 RMB (5,143 USD), respectively, indicating that the cost increased significantly with increasing dementia severity. In terms of the quality of life, the combined total score for the Quality of Life-Alzheimer's Disease scale was 30.11, with lower scores for the Housekeeping, Recreation, and Memory items. Dementia imposes a significant economic and quality of life burden on Chinese patients. The government should pay more attention to dementia and develop a comprehensive prevention and treatment system to reduce the heavy burden of dementia. This systematic review has the registration number CRD42022374470 on PROSPERO.

Effects of long-term exposure to high-altitude on episodic memory: The moderating role of daytime dysfunction

Chronic exposure to high-altitude hypoxic environments may influence short-term memory and working memory. However, its impact on long-term memory, specifically episodic memory, remains understudied. In this study, we systematically investigated the effects of long-term exposure to high altitude (3650 m) on episodic memory, including item memory and source memory. Moreover, we examined the moderating role of daytime dysfunction on the relationship between altitude and episodic memory. In total, 97 participants were enrolled in the study: 49 were from the high-altitude (HA) group, comprising those born and raised in low altitude (LA) areas (< 500 m) and had migrated to HA for 2∼3 years after turning 18; and 48 were from the LA group, who had never lived at high altitudes. Episodic memory was evaluated using a what-when-where task, whereas daytime dysfunction was measured by the Pittsburgh Sleep Quality Index. For item memory, hit rate and correct rejection rate were significantly lower in the HA group relative to the LA group. For source binding memory, the performance in what-where binding and what-when-where binding were decreased in the HA group, but the what-when binding did not differ between the two groups. Furthermore, the effects of altitude on hit rate, what-where binding, and what-when-where binding were significantly pronounced in individuals with higher levels of daytime dysfunction. These findings suggest that long-term exposure to high-altitude hypoxic environments influences episodic memory performance, including item recognition and source-binding memory. Specifically, spatial source memory is affected by high-altitude exposure, whereas temporal source memory remains unaffected. Moreover, these results highlight the importance of considering sleep quality, especially good daytime function, in maintaining optimal episodic memory function following chronic exposure to high altitudes.

Latent memory traces for prospective items in visual working memory

Latent memory traces for prospective items in visual working memory

Categorically distinct subsets allow flexible memory selection in hybrid search.

In many everyday situations, we search our visual surroundings for any one of many memorized items held in memory, a process termed hybrid search. In some cases, only a portion of the memorized mental list is relevant within a specific visual context, thus, restricting memory search to the relevant subset would be desirable. Previous research had shown that participants largely fail to "partition" memory into several distinct subsets, on a trial-by-trial basis. However, given the known role of semantic content in long-term memory organization, we hypothesized that semantically defined subset categories might serve as a more powerful means for flexible memory selection in dynamic hybrid search situations. Experiment 1 revealed that, indeed, semantic characteristics (i.e., object category), but not perceptual features (e.g., arbitrary color), can provide a firm basis for flexible memory partitioning. Experiments 2 and 3 further showed that such memory partitioning is costless and is independent of the nature of the surrounding visual distractors (i.e., a categorically homogeneous or heterogeneous display). These findings demonstrate that confining one's memory search to a currently relevant subset of items is highly effective when the different memory subsets are defined by clear semantic categories. The results underscore the importance of conceptual information in the organization of activated long-term memory and in forming the basis for a flexible trial-by-trial memory selection. Our findings further highlight the relationship between visual search and memory search, and they may shed light on the processes contributing to a successful construction of bounded episodes in long-term memory. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Attentional boost effect: research based on source memory and emotional materials.

The attentional boost effect (ABE) refers to the phenomenon that stimuli which appear with targets in a detection task are better remembered than those that appear with distractors. Previous studies have consistently reported a robust ABE in item memory, but inconsistent conclusions have been drawn for source memory. Additionally, regarding the impact of emotional stimuli on the ABE, conclusions have also been inconsistent. The aim of this research was to clarify these inconsistencies. In Experiment 1, participants were asked to memorize different emotional background words (primary task), monitor the symbols above the words, press the spacebar when encountering the "+" (secondary task), and remember the size of the emotional background stimuli (as a source feature). Results revealed that the ABE of negative stimuli was stronger in item memory. For source memory, an ABE was observed only for large fonts. In Experiment 2, participants performed the same task as in Experiment 1, except for recalling the color of emotional stimuli instead of their size. Results indicated a stronger ABE for emotional stimuli in item memory, with no ABE observed in source memory. These findings suggest: (1) Item and source memory are regulated by distinct cognitive processes, leading to differential effects of emotionality on ABE in both types of memory. (2) Contrary to previous literature, emotional stimuli, such as negative words, do not consistently diminish the ABE.

Distress reactions and susceptibility to misinformation for an analogue trauma event

Accuracy of memory is critical in legal and clinical contexts. These contexts are often linked with high levels of emotional distress and social sources that can provide potentially distorting information about stressful events. This study investigated how distress was associated with susceptibility to misinformation about a trauma analogue event. We employed an experimental design whereby in Phase 1, participants (N = 243, aged 20–72, 122 females, 117 males, 4 gender diverse) watched a trauma film (car crash) and heard an audio summary that contained misinformation (misled items), true reminders (consistent items), and no reminders (control items) about the film. Participants rated their total distress, and symptoms of avoidance, intrusions, and hyperarousal, in response to the film. They then completed cued recall, recognition, and source memory tasks. One week later in Phase 2, participants (N = 199) completed the same measures again. Generalised linear mixed models were used. A significant misinformation effect was found, and importantly, participants with higher distress levels showed a smaller misinformation effect, owing to especially poor memory for consistent items compared to their less distressed counterparts. Distress was also associated with improved source memory for misled items. Avoidance of the film’s reminders was associated with a smaller misinformation effect during immediate retrieval and a larger misinformation effect during delayed retrieval. Findings suggest that distress is associated with decreased susceptibility to misinformation in some cases, but also associated with poorer memory accuracy in general. Limitations are discussed, and the need for further research is highlighted.

Classification of Known and Unknown Study Items in a Memory Task Using Single-Trial Event-Related Potentials and Convolutional Neural Networks.

This study examines the feasibility of using event-related potentials (ERPs) obtained from electroencephalographic (EEG) recordings as biomarkers for long-term memory item classification. Previous studies have identified old/new effects in memory paradigms associated with explicit long-term memory and familiarity. Recent advancements in convolutional neural networks (CNNs) have enabled the classification of ERP trials under different conditions and the identification of features related to neural processes at the single-trial level. We employed this approach to compare three CNN models with distinct architectures using experimental data. Participants (N = 25) performed an association memory task while recording ERPs that were used for training and validation of the CNN models. The EEGNET-based model achieved the most reliable performance in terms of precision, recall, and specificity compared with the shallow and deep convolutional approaches. The classification accuracy of this model reached 62% for known items and 66% for unknown items. Good overall accuracy requires a trade-off between recall and specificity and depends on the architecture of the model and the dataset size. These results suggest the possibility of integrating ERP and CNN into online learning tools and identifying the underlying processes related to long-term memorization.

Evidence for separate backward recall and n-back working memory factors: a large-scale latent variable analysis

ABSTRACT Multiple studies have explored the factor structure of working memory (WM) tasks, yet few have done so controlling for both the domain and category of the memory items in a single study. In the current pre-registered study, we conducted a large-scale latent variable analysis using variant forms of n-back and backward recall tasks to test whether they measured a single underlying construct, or were distinguished by stimuli-, domain-, or paradigm-specific factors. Exploratory analyses investigated how the resulting WM factor(s) were linked to fluid intelligence. Participants (N = 703) completed a fluid reasoning test and multiple n-back and backward recall tasks containing memoranda that varied across (spatial or verbal material) and within (verbal digits or letters) domain, allowing the variance specific to task content and paradigm to be assessed. Two distinct but related backward recall and n-back constructs best captured the data, in comparison to other plausible model constructions (single WM factor, two-factor domain, and three-factor materials models). Common variance associated with WM was a stronger predictor of fluid reasoning than a residual n-back factor, but the backward recall factor predicted fluid reasoning as strongly as the common WM factor. These data emphasise the distinctiveness between backward recall and n-back tasks.

Prefrontal and lateral entorhinal neurons co-dependently learn item-outcome rules.

The ability to learn novel items depends on brain functions that store information about items classified by their associated meanings and outcomes1-4, but the underlying neural circuit mechanisms of this process remain poorly understood. Here we show that deep layers of the lateral entorhinal cortex (LEC) contain two groups of 'item-outcome neurons': one developing activity for rewarded items during learning, and another for punished items. As mice learned an olfactory item-outcome association, we found that the neuronal population of LEC layers 5/6 (LECL5/6) formed an internal map of pre-learned and novel items, classified into dichotomic rewarded versus punished groups. Neurons in the medial prefrontal cortex (mPFC), which form a bidirectional loop circuit with LECL5/6, developed an equivalent item-outcome rule map during learning. When LECL5/6 neurons were optogenetically inhibited, tangled mPFC representations of novel items failed to split into rewarded versus punished groups, impairing new learning by mice. Conversely, when mPFC neurons were inhibited, LECL5/6 representations of individual items were held completely separate, disrupting both learning and retrieval of associations. These results suggest that LECL5/6 neurons and mPFC neurons co-dependently encode item memory as a map of associated outcome rules.