Showing papers on "Interference theory published in 2021"

Evidence against a large effect of sleep in protecting verbal memories from interference.

Abstract: The human brain has evolved to acquire novel information rapidly while serving the need to store long-term memories in a stable and lasting form. Presenting interfering information directly after learning can lead to forgetting of the original material. It has been suggested that sleep aids the stabilization of new memories and protects them from interference. Here, we aim to replicate in two separate experiments the claim that sleep protects memories from retroactive interference (Current Biology, 16, 2006 and 1290; PLoS ONE, 4, 2009 and e4117). We let participants study wordlists before letting them sleep for an afternoon nap or for a full night. In a control condition, subjects stayed awake for the same amount of time. After the consolidation interval, participants learnt an interfering wordlist and were tested on memory of the original wordlist. Sleep did not stabilize memory for the original wordlist in either study. We discuss our findings in the light of recent advances in computational neuroscience, and conclude that the stabilizing effect of sleep against interference has been overestimated.

Abrupt hippocampal remapping signals resolution of memory interference.

Abstract: Remapping refers to a decorrelation of hippocampal representations of similar spatial environments. While it has been speculated that remapping may contribute to the resolution of episodic memory interference in humans, direct evidence is surprisingly limited. We tested this idea using high-resolution, pattern-based fMRI analyses. Here we show that activity patterns in human CA3/dentate gyrus exhibit an abrupt, temporally-specific decorrelation of highly similar memory representations that is precisely coupled with behavioral expressions of successful learning. The magnitude of this learning-related decorrelation was predicted by the amount of pattern overlap during initial stages of learning, with greater initial overlap leading to stronger decorrelation. Finally, we show that remapped activity patterns carry relatively more information about learned episodic associations compared to competing associations, further validating the learning-related significance of remapping. Collectively, these findings establish a critical link between hippocampal remapping and episodic memory interference and provide insight into why remapping occurs. When two memories are similar, their encoding and retrieval can be disrupted by each other. Here the authors show that memory interference is resolved through abrupt remapping of activity patterns in the human hippocampal CA3 and dentate gyrus.

Testing potential mechanisms underlying test-potentiated new learning.

Abstract: An emerging body of studies demonstrates that practicing retrieval of studied information, by comparison with restudying or no treatment, can facilitate subsequent learning and retrieval of new information, a phenomenon termed the forward testing effect (FTE) or test-potentiated new learning. Several theoretical explanations have been proposed to account for the FTE. A release-from-PI theory proposes that interpolated testing induces context changes and enhances event segregation, which in turn protect new learning from proactive interference (PI). A strategy-change view hypothesizes that prior tests teach learners to adopt more effective/elaborative learning and retrieval strategies in subsequent study and test phases. Finally, a reset-of-encoding account proposes that interim testing on studied information reduces memory load, resets the subsequent encoding process, and enhances encoding of new information. The current study recruited a large sample (over 1,000 participants) and employed a multilist learning task and mediation analyses to test these theories. The results suggest that prior list intrusions (an index of PI) significantly mediated the FTE, supporting the release-from-PI theory. In addition, interim testing enhanced strategic processing of temporal information during new learning (reflected by increased clustering), and temporal clustering significantly mediated the FTE, supporting a role for strategy-change in the FTE. Lastly, a variety of indices were constructed to represent the benefit of reset-of-encoding, but none of them provided evidence supporting the reset-of-encoding view. The results shed new light on the complex mechanisms underlying the forward benefits of testing. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Episodic memory enhancement versus impairment is determined by contextual similarity across events.

Abstract: For over a century, stability of spatial context across related episodes has been considered a source of memory interference, impairing memory retrieval. However, contemporary memory integration theory generates a diametrically opposite prediction. Here, we aimed to resolve this discrepancy by manipulating local context similarity across temporally disparate but related episodes and testing the direction and underlying mechanisms of memory change. A series of experiments show that contextual stability produces memory integration and marked reciprocal strengthening. Variable context, conversely, seemed to result in competition such that new memories become enhanced at the expense of original memories. Interestingly, these patterns were virtually inverted in an additional experiment where context was reinstated during recall. These observations 1) identify contextual similarity across original and new memories as an important determinant in the volatility of memory, 2) present a challenge to classic and modern theories on episodic memory change, and 3) indicate that the sensitivity of context-induced memory changes to retrieval conditions may reconcile paradoxical predictions of interference and integration theory.

Working memory recruits long-term memory when it is beneficial: Evidence from the Hebb effect.

Abstract: When encoding task-relevant information in working memory (WM), we can use prior knowledge to facilitate task performance. For instance, when memorizing a phone number, we can benefit from recognizing some parts as known chunks (e.g., 911) and focus on memorizing the novel parts. Prior knowledge from long-term memory (LTM), however, can also proactively interfere with WM contents. Here, we show that WM selectively recruits information from LTM only when it is helpful, not when it would interfere. We used variants of the Hebb paradigm in which WM is tested through immediate serial recall of lists. Some lists were repeated frequently across trials, so they were acquired in LTM, as reflected in increasing serial-recall performance across repetitions. We compared interference conditions in which that LTM knowledge could interfere with holding another list in WM to a neutral condition in which that knowledge could be neither beneficial nor harmful. In Experiments 1-3, lists in the interference conditions shared their items with the learned lists but not their order. We observed no proactive interference. In Experiments 4 and 5, the interference lists' first three items overlapped exactly with the learned lists, and only the remaining items had a new order. This made LTM knowledge partially beneficial and partially harmful. Participants could use LTM flexibly to improve performance for the first part of the list without experiencing interference on the second half. LTM-mediated learning of the first part even boosted memory for the unknown second part. We conclude that there is a flexible gate controlling the flow of information from LTM and WM so that LTM knowledge is recruited only when helpful. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Proactive interference in working memory is related to adult age and cognitive factors: cross-sectional and longitudinal evidence from the Betula study.

Abstract: In working memory (WM), successful maintenance of information is affected by interference. Older adults may be especially susceptible to the effects of interference, which may cause age-related cog...

Retroactive interference model of forgetting

Abstract: Memory and forgetting constitute two sides of the same coin, and although the first has been extensively investigated, the latter is often overlooked. A possible approach to better understand forgetting is to develop phenomenological models that implement its putative mechanisms in the most elementary way possible, and then experimentally test the theoretical predictions of these models. One such mechanism proposed in previous studies is retrograde interference, stating that a memory can be erased due to subsequently acquired memories. In the current contribution, we hypothesize that retrograde erasure is controlled by the relevant “importance” measures such that more important memories eliminate less important ones acquired earlier. We show that some versions of the resulting mathematical model are broadly compatible with the previously reported power-law forgetting time course and match well the results of our recognition experiments with long, randomly assembled streams of words.

Neurogenesis-induced forgetting is associated with reduced neuronal activity in CA1 during context fear memory retrieval

Abstract: Hippocampal neurogenesis has a role in many essential learning and memory processes, including forgetting. This forgetting process is important because it prevents proactive interference between old and new memories. While several studies have now established the role of neurogenesis in forgetting, the specific mechanisms mediating neurogenesis-induced forgetting have not been elucidated. The goal of this study was to examine how increased neurogenesis affects the recall of context fear memory in addition to its effects on population activity within hippocampal subregions. We trained mice in contextual fear conditioning and then increased neurogenesis via 4 weeks of voluntary wheel running. Increased neurogenesis led to a reduction in freezing behaviour during context testing, replicating previous studies showing that increased neurogenesis causes forgetting of context fear memories. Additionally, we mapped the expression of the immediate early gene c-Fos within hippocampal subregions and found that increasing neurogenesis led to reduced CA1 c-Fos expression during context testing. The results suggest that reduced CA1 population activity may underlie the association between increased neurogenesis and forgetting.

Post‐training stimulation of the right dorsolateral prefrontal cortex impairs working memory training performance

Abstract: Research investigating transcranial direct current stimulation (tDCS) to enhance cognitive training augments both our understanding of its long-term effects on cognitive plasticity as well as potential applications to strengthen cognitive interventions. Previous work has demonstrated enhancement of working memory training while applying concurrent tDCS to the dorsolateral prefrontal cortex (DLPFC). However, the optimal stimulation parameters are still unknown. For example, the timing of tDCS delivery has been shown to be an influential variable that can interact with task learning. In the present study, we used tDCS to target the right DLPFC while participants trained on a visuospatial working memory task. We sought to compare the relative efficacy of online stimulation delivered during training to offline stimulation delivered either immediately before or afterwards. We were unable to replicate previously demonstrated benefits of online stimulation; however, we did find evidence that offline stimulation delivered after training can actually be detrimental to training performance relative to sham. We interpret our results in light of evidence suggesting a role of the right DLPFC in promoting memory interference, and conclude that while tDCS may be a promising tool to influence the results of cognitive training, more research and an abundance of caution are needed before fully endorsing its use for cognitive enhancement. This work suggests that effects can vary substantially in magnitude and direction between studies, and may be heavily dependent on a variety of intervention protocol parameters such as the timing and location of stimulation delivery, about which our understanding is still nascent.

Repeatedly Measuring Political Interest: Can we Reduce Respondent’ Recall Ability and Memory Effects in Surveys Using Memory Interference Tasks?

Abstract: It is common practice in behavioral and social sciences to repeat questions, such as in pretest–posttest designs. However, if respondents recall their first answer to a repeated question and use it to decide their second answer, this may cause memory effects, affecting empirical findings. So far, only a few studies have investigated respondents’ recall ability and memory effects in surveys. Thus, we conducted an experiment in a probability-based online panel (N = 4,681) where we repeatedly asked a question on political interest. Our results reveal that respondents’ recall ability is high and was not reduced by the implementation of memory interference tasks. Memory effects, in contrast, were low (about 7%). They were also not reduced by memory interference tasks.

Adaptive Memory Distortions Are Predicted by Feature Representations in Parietal Cortex.

Abstract: Similarity between memories is a primary cause of interference and forgetting. Exaggerating subtle differences between memories is therefore a potential mechanism for reducing interference. Here, we report a human fMRI study (n = 29, 19 female) that tested whether behavioral and neural expressions of memories are adaptively distorted to reduce interference. Participants learned and repeatedly retrieved object images, some of which were identical except for subtle color differences. Behavioral measures of color memory revealed exaggeration of differences between similar objects. Importantly, greater memory exaggeration was associated with lower memory interference. fMRI pattern analyses revealed that color information in parietal cortex was stronger during memory recall when color information was critical for discriminating competing memories. Moreover, greater representational distance between competing memories in parietal cortex predicted greater color memory exaggeration and lower memory interference. Together, these findings reveal that competition between memories induces adaptive, feature-specific distortions in parietal representations and corresponding behavioral expressions.SIGNIFICANCE STATEMENT Similarity between memories is a primary cause of interference and forgetting. Here, we show that, when remembering highly similar objects, subtle differences in the features of these objects are exaggerated in memory to reduce interference. These memory distortions are reflected in, and predicted by, overlap of activity patterns in lateral parietal cortex. These findings provide unique insight into how memory interference is resolved and specifically implicate lateral parietal cortex in representing feature-specific memory distortions.

Dissociating the effects of delay and interference on dog (Canis familiaris) working memory.

Abstract: Delayed matching-to-sample (dMTS) is commonly used to study working memory (WM) processes in non-humans. Previous procedures for studying dog WM, including versions of the dMTS, did not separate the impact of delay and interference on memory performance. These studies were also limited to auditory and spatial stimuli, neglecting dogs' dominant sensory modality (i.e., olfaction). Therefore, we designed the first olfactory dMTS in dogs, with systematically varied delays and number of odors in a session, to dissociate the effects of delay and within-session proactive interference on dog WM. Dogs (n = 5) initially trained on matching-to-sample with 48 odors, with a zero-second delay, were tested on four delay lengths (0, 30, 60, and 90 s), counterbalanced across three, trial-unique, sessions. Although there was a slight decrease in accuracy across delays, dogs performed above chance on delays up to 60 s, suggesting a WM duration of at least 60 s. To explore the effect of within-session proactive interference on WM duration, the size of the stimulus set was reduced to six and two odors. There was no effect on the memory function with six odors compared to the trial-unique sessions. However, the interference caused by the two-odor set was enough to decrease accuracy at each delay length. These findings suggest that forgetting in dog working memory for odors can be simultaneously influenced by delay and within-session proactive interference.

Great tits who remember more accurately have difficulty forgetting, but variation is not driven by environmental harshness.

Abstract: The causes of individual variation in memory are poorly understood in wild animals. Harsh environments with sparse or rapidly changing food resources are hypothesized to favour more accurate spatial memory to allow animals to return to previously visited patches when current patches are depleted. A potential cost of more accurate spatial memory is proactive interference, where accurate memories block the formation of new memories. This relationship between spatial memory, proactive interference, and harsh environments has only been studied in scatter-hoarding animals. We compare spatial memory accuracy and proactive interference performance of non-scatter hoarding great tits (Parus major) from high and low elevations where harshness increases with elevation. In contrast to studies of scatter-hoarders, we did not find a significant difference between high and low elevation birds in their spatial memory accuracy or proactive interference performance. Using a variance partitioning approach, we report the first among-individual trade-off between spatial memory and proactive interference, uncovering variation in memory at the individual level where selection may act. Although we have no evidence of harsh habitats affecting spatial memory, our results suggest that if elevation produced differences in spatial memory between elevations, we could see concurrent changes in how quickly birds can forget.

The Impact of Acute Exercise Timing on Memory Interference.

Abstract: This study evaluated whether the timing of acute exercise can attenuate a memory interference effect Across two experiments, participants completed an AB/AC memory task Participants studied eight

Poor Mnemonic Discrimination Predicts Overgeneralization of Fear

Abstract: Anxiety disorders are characterized by difficulty distinguishing safe contexts from previous or imagined threats. Conditioned fears spread beyond what is reasonable or adaptive, leading to broad and interfering anxieties when people overgeneralize their fears. Difficulties with mnemonic discrimination, a component process of memory supporting the integration of old and new experiences, may foster overgeneralization and increase risk for anxiety disorders. Individuals along a spectrum of anxiety severity (n = 117) completed a differential fear conditioning paradigm and the computerized Mnemonic Similarity Task. The task measures mnemonic discrimination by requiring individuals to differentiate between highly similar old and new entities. We predicted that low mnemonic discrimination would be associated with overgeneralization, i.e., flatter slopes of change in response to stimuli increasingly dissimilar to the conditioned stimulus. Conditional growth models showed that as expected, participants with the highest mnemonic discrimination scores also exhibited the steepest declines in fear ratings as stimuli increasingly differed from the conditioned stimulus. Results were unchanged after adjusting for recognition memory, self-reported anxiety, and clinical diagnoses and symptoms. Results support the hypothesis that memory interference (i.e., low mnemonic discrimination) could increase vulnerability for overgeneralization. Findings justify additional exploration of mnemonic discrimination and its role in anxious psychopathology.

Adult neurogenesis mediates forgetting of multiple types of memory in the rat

Abstract: The formation and retention of hippocampus-dependent memories is impacted by neurogenesis, a process that involves the production of new neurons in the dentate gyrus of the hippocampus. Recent studies demonstrate that increasing neurogenesis after memory formation induces forgetting of previously acquired memories. Neurogenesis-induced forgetting was originally demonstrated in mice, but a recent report suggests that the same effect may be absent in rats. Although a general species difference is possible, other potential explanations for these incongruent findings are that memories which are more strongly reinforced become resilient to forgetting or that perhaps only certain types of memories are affected. Here, we investigated whether neurogenesis-induced forgetting occurs in rats using several hippocampal dependent tasks including contextual fear conditioning (CFC), the Morris Water Task (MWT), and touchscreen paired associates learning (PAL). Neurogenesis was increased following training using voluntary exercise for 4 weeks before recall of the previous memory was assessed. We show that voluntary running causes forgetting of context fear memories in a neurogenesis-dependent manner, and that neurogenesis-induced forgetting is present in rats across behavioral tasks despite differences in complexity or reliance on spatial, context, or object memories. In addition, we asked whether stronger memories are less susceptible to forgetting by varying the strength of training. Even with a very strong training protocol in the CFC task, we still observed enhanced forgetting related to increased neurogenesis. These results suggest that forgetting due to neurogenesis is a conserved mechanism that aids in the clearance of memories. Significance Statement Recent evidence indicates that hippocampal neurogenesis mediates forgetting of older memories and enhances encoding of new memories free of proactive interference. This evidence comes from multiple rodent species, behavioral tasks, and methods of increasing neurogenesis. However, a recent paper by (Kodali et al. 2016) found that voluntary exercise-induced neurogenesis did not cause forgetting in the Morris Water Task in rats. The results call into question whether the phenomenon is a conserved function of neurogenesis across species. In the present study, we show that voluntary running causes robust forgetting in rats in a neurogenesis-dependent manner and that the effect is present across three different behavioral tasks, confirming the existence of the phenomenon in rats and adding to the growing evidence that forgetting is a conserved function of hippocampal neurogenesis.

The role of prior-event retrieval in encoding changed event features.

Abstract: When people experience everyday activities, their comprehension can be shaped by expectations that derive from similar recent experiences, which can affect the encoding of a new experience into memory. When a new experience includes changes—such as a driving route being blocked by construction—this can lead to interference in subsequent memory. One potential mechanism of effective encoding of event changes is the retrieval of related features from previous events. Another such mechanism is the generation of a prediction error when a predicted feature is contradicted. In two experiments, we tested for effects of these two mechanisms on memory for changed features in movies of everyday activities. Participants viewed movies of an actor performing everyday activities across two fictitious days. Some event features changed across the days, and some features violated viewers’ predictions. Retrieval of previous event features while viewing the second movie was associated with better subsequent memory, providing evidence for the retrieval mechanism. Contrary to our hypotheses, there was no support for the error mechanism: Prediction error was not associated with better memory when it was observed correlationally (Experiment 1) or directly manipulated (Experiment 2). These results support a key role for episodic retrieval in the encoding of new events. They also indicate boundary conditions on the role of prediction errors in driving new learning. Both findings have clear implications for theories of event memory.

Neural Underpinnings of Proactive Interference in Working Memory: Evidence From Patients With Unilateral Lesions

Abstract: Proactive interference in working memory refers to the fact that memory of past experiences can interfere with the ability to hold new information in working memory. The left inferior frontal gyrus (LIFG) has been proposed to play an important role in resolving proactive interference in working memory. However, the role of white matter pathways and other cortical regions has been less investigated. Here we investigated proactive interference in working memory using the Recent Probes Test (RPT) in 15 stroke patients with unilateral chronic lesions in left (n = 7) or right (n = 2) prefrontal cortex (PFC), or left temporal cortex (n = 6). We examined the impact of lesions in both gray and white matter regions on the size of the proactive interference effect. We found that patients with left PFC lesions performed worse overall, but the proactive interference effect in this patient group was comparable to that of patients with right PFC lesions, temporal lobe lesions, and controls. Interestingly, the size of the interference effect was significantly correlated with the degree of damage in the extreme/external capsule and marginally correlated with the degree of damage in the inferior frontal occipital fasciculus (IFOF). These findings suggests that ventral white matter pathways connecting the LIFG to left posterior regions play a role in resolving proactive interference in working memory. This effect was particularly evident in one patient with a very large interference effect (>3 SDs above controls) who had mostly spared LIFG, but virtually absent ventral white matter pathways (i.e., passing through the extreme/external capsules and IFOF). This case study further supports the idea that the role of the LIFG in resolving interference in working memory is dependent on connectivity with posterior regions via ventral white matter pathways.

The influence of long-term memory on working memory: Age-differences in proactive facilitation and interference

Abstract: Prior learning can hinder subsequent memory, especially when there is conflict between old and new information The ability to handle this proactive interference is an important source of differences in memory performance between younger and older adults In younger participants, Oberauer et al (2017, Journal of Experimental Psychology: Learning, Memory, and Cognition, 43[1], 1) report evidence of proactive facilitation from previously learned information in a working memory task in the absence of proactive interference between long-term and working memory In the present work, we examine the generality of these findings to different stimulus materials and to older adults Participants first learned image–word associations and then completed an image–word working memory task Some pairs were the same as those initially learned, for which we expected facilitation relative to previously unencountered pairs Other pairs were made up of previously learned elements in different combinations, for which we might expect interference Younger and older participants showed similar levels of facilitation from previously learned associations relative to new pairs In addition, older participants exhibited proactive interference from long-term to working memory, whereas younger participants exhibited facilitation, even for pairings that conflicted with those learned earlier in the experiment These findings confirm older adults’ greater susceptibility to proactive interference and we discuss the theoretical implications of younger adults’ apparent immunity to interference

Emotionally valenced and modality-specific dual tasks: Effects on voluntary reminding and proactive interference in trauma-exposed individuals suffering from PTSD.

Abstract: Objectives: People suffering from posttraumatic stress disorder (PTSD) often experience distressing traumatic memories. Therapeutic methods that apply a secondary task while clients recall a trauma memory may further assist in modifying the vividness and emotionality of the trauma memory and in reducing intrusions. In this experiment, we aimed to investigate whether the emotional valence (positive vs. neutral) and sensory modality (visual vs. auditory) of a secondary task reduces the vividness and emotionality of the trauma memory and the proactive interference. Method: Sixty PTSD patients exposed to road traffic accident traumas were randomized to one of four groups in a 2 (emotional valence: positive, neutral) × 2 (modality: visual, auditory) design. Participants were then exposed to a positive or a neutral clip that was visual or auditory and were required to recall the trauma memory during exposure to the clip. Vividness and emotionality of the trauma memory and proactive interference were assessed before and after exposure to the clip and at a 1-week follow-up. Results: Results revealed that participants who recalled the trauma memory while exposed to the positive clip reported their trauma memory as being less distressing (but not less vivid) and indicated less proactive interference than did participants exposed to the neutral clip. Nevertheless, modality had no significant effect in attenuating the proactive interference under conditions of modality congruence. Conclusion: Inducing positive emotion while performing a dual task may be an effective module in therapeutic approaches. (PsycInfo Database Record (c) 2021 APA, all rights reserved).