Remembering can cause forgetting: retrieval dynamics in long-term memory

Phase separation of competing memories along the human hippocampal theta rhythm

Competition between overlapping memories is considered one of the major causes of forgetting, and it is still unknown how the human brain resolves such mnemonic conflict. In the present magnetoencephalography (MEG) study, we empirically tested a computational model that leverages an oscillating inhibition algorithm to minimise overlap between memories. We used a proactive interference task, where a reminder word could be associated with either a single image (non-competitive condition) or two competing images, and participants were asked to always recall the most recently learned word–image association. Time-resolved pattern classifiers were trained to detect the reactivated content of target and competitor memories from MEG sensor patterns, and the timing of these neural reactivations was analysed relative to the phase of the dominant hippocampal 3 Hz theta oscillation. In line with our pre-registered hypotheses, target and competitor reactivations locked to different phases of the hippocampal theta rhythm after several repeated recalls. Participants who behaviourally experienced lower levels of interference also showed larger phase separation between the two overlapping memories. The findings provide evidence that the temporal segregation of memories, orchestrated by slow oscillations, plays a functional role in resolving mnemonic competition by separating and prioritising relevant memories under conditions of high interference.

Examining the effect size and duration of retrieval-induced facilitation

Under certain conditions, the retrieval of some information can increase the recall of other information, a phenomenon known as retrieval-induced facilitation. Chan (Journal of Memory and Language 61:153–170, 2009) proposed two moderating factors to account for why retrieval causes facilitation in some situations and forgetting in others: (1) integration at the time of encoding and (2) the delay between retrieval practice and final test. Chan found a 9–11% facilitation effect when the materials were well integrated and the final test occurred after a 24-h delay. Two sets of experiments sought to replicate and extend Chan’s study by examining retrieval-induced facilitation not only following a 24-h delay but after longer delays (i.e., 1 or 2 weeks). A meta-analysis including these replications and the original experiments was also conducted. The results provide additional evidence of retrieval-induced facilitation, with no evidence that the effect varies as a function of the final delay. However, the size of the effect was found to be somewhat smaller than previously observed.

Simple contextual cueing prevents retroactive interference in short-term perceptual training of orientation detection tasks

Perceptual training of multiple tasks suffers from interference between the trained tasks. Here, we conducted five psychophysical experiments with separate groups of participants to investigate the possibility of preventing the interference in short-term perceptual training. We trained the participants to detect two orientations of Gabor stimuli in two adjacent days at the same retinal location and examined the interference of training effects between the two orientations. The results showed significant retroactive interference from the second orientation to the first orientation (Experiment 1 and Experiment 2). Introducing a 6-h interval between the pre-test and training of the second orientation did not eliminate the interference effect, excluding the interpretation of disrupted reconsolidation as the pre-test of the second orientation may reactivate and destabilize the representation of the first orientation (Experiment 3). Finally, the training of the two orientations was accompanied by fixations in two colors, each serving as a contextual cue for one orientation. The results showed that the retroactive interference was not evident if the participants passively perceived contextual cues during the training and test sessions (Experiment 4). Importantly, this facilitation effect could be observed if the contextual cues appeared only during the training, demonstrating the robustness of the effect (Experiment 5). Our findings suggest that the retroactive interference effect in short-term perceptual training of orientation detection tasks was likely the result of higher-level factors such as shared contextual cues embedded in the tasks. The efficiency of multiple perceptual trainings could be facilitated by associating the trained tasks with different contextual cues.

Long-term memory interference is resolved via repulsion and precision along diagnostic memory dimensions

When memories share similar features, this can lead to interference, and ultimately forgetting. With experience, however, interference can be resolved. This raises the important question of how memories change, with experience, to minimize interference. Intuitively, interference might be minimized by increasing the precision and accuracy of memories. However, recent evidence suggests a potentially adaptive role for memory distortions. Namely, similarity can trigger exaggerations of subtle differences between memories (repulsion). Here, we tested whether repulsion specifically occurs on feature dimensions along which memories compete and whether repulsion is predictive of reduced memory interference. To test these ideas, we developed synthetic faces in a two-dimensional face space (affect and gender). This allowed us to precisely manipulate similarity between faces and the feature dimension along which faces differed. In three experiments, participants learned to associate faces with unique cue words. Associative memory tests confirmed that when faces were similar (face pairmates), this produced interference. Using a continuous face reconstruction task, we found two changes in face memory that preferentially occurred along the feature dimension that was “diagnostic” of the difference between face pairmates: (1) there was a bias to remember pairmates with exaggerated differences (repulsion) and (2) there was an increase in the precision of feature memory. Critically, repulsion and precision were each associated with reduced associative memory interference, but these were statistically dissociable contributions. Collectively, our findings reveal that similarity between memories triggers dissociable, experience-dependent changes that serve an adaptive role in reducing interference.

Retrieval-induced forgetting in children and adolescents with and without obesity

BACKGROUND/OBJECTIVES

Previous research indicates that youth with obesity exhibit deficits in executive functioning (EF), which often take the form of impaired response inhibition. One aspect of EF not previously studied in obesity is the adaptive process known as retrieval-induced forgetting (RIF), the suppression/inhibition of intrusive or non-target items by the retrieval of specific items from memory. The present study investigated if child or adolescent obesity disrupts the ability to inhibit retrieval of intrusive memories.

SUBJECTS/METHODS

We compared the manifestation of RIF in children (ages 8-12) and adolescents (ages 13-18) as a function of their weight status and sex. We also evaluated the effects of these variables on simple recall of items from episodic memory under conditions where competition from intrusive items was reduced.

RESULTS

Children with obesity did not demonstrate significant RIF, whereas RIF was exhibited by preteens without obesity and by teenage participants with- and without obesity (Weight Status × Age Group interaction p = 0.028). This pattern of results did not differ as a function of sex for either age group. No differences in episodic memory were found. Additional analyses using Age as continuous covariate (and not as a nominal group) comparing participants who exhibited RIF with those who did not, found that the no RIF group consumed fast-food meals more frequently (p = 0.024) and had higher percentages of total body adiposity and android fat compared to the RIF group (p's < 0.05).

CONCLUSIONS

The findings expand what is known about the effects of childhood obesity on cognitive functioning, identify impaired RIF with specific behavioral and dietary factors and increased adiposity, and suggest the possibility that impairments in the ability to inhibit intrusive memories of food and eating may contribute to poor early-life weight control.

Suppression of non-selected solutions as a possible brain mechanism for ambiguity resolution in the word fragment task completion task

Brain systems dealing with multiple meanings of ambiguous stimuli are relatively well studied, while the processing of non-selected meanings is less investigated in the neurophysiological literature and provokes controversy between existing theories. It is debated whether these meanings are actively suppressed and, if yes, whether suppression characterizes any task that involves alternative solutions or only those tasks that emphasize semantic processing or the existence of alternatives. The current functional MRI event-related study used a modified version of the word fragment completion task to reveal brain mechanisms involved in implicit processing of the non-selected solutions of ambiguous fragments. The stimuli were pairs of fragmented adjectives and nouns. Noun fragments could have one or two solutions (resulting in two words with unrelated meanings). Adjective fragments had one solution and created contexts strongly suggesting one solution for ambiguous noun fragments. All fragmented nouns were presented twice during the experiment (with two different adjectives). We revealed that ambiguity resolution was associated with a reduced BOLD signal within several regions related to language processing, including the anterior hippocampi and amygdala and posterior lateral temporal cortex. Obtained findings were interpreted as resulting from brain activity inhibition, which underlies a hypothesized mechanism of suppression of non-selected solutions.

Rate of forgetting is independent of initial degree of learning

It is commonly assumed that the rate of forgetting depends on initial degree of learning. Hence, comparison of forgetting across groups is usually carried out equating initial performance. However, these matching procedures add confounding variables. In four experiments, following Slamecka and McElree (1983, Exp 3), we challenge this assumption through manipulating initial acquisition by varying the number of presentations of the material and studying the effect on rate of subsequent forgetting. A set of 36 sentences was presented either visually or auditorily. Different participants were exposed to the material two, four or six times. Forgetting was measured by means of a cued recall test at three time-intervals (30 s, 1 day and 1 week in experiments 1 and 2; 30 s, 1 day, and 3 days in experiments 3 and 4). A different subset of 12 sentences was tested at each delay. The outcome of these experiments showed that the initial acquisition depends on number of learning trials. However, the rate of forgetting proved to be independent of initial acquisition. This pattern remains constant across modalities of presentation and of the number of learning trials. The conclusion is that forgetting does not depend on initial acquisition.

The Trajectory of Targets and Critical Lures in the Deese/Roediger-McDermott Paradigm: A Systematic Review

The Deese/Roediger-McDermott (DRM) paradigm has been used extensively to examine false memory. During the study session, participants learn lists of semantically related items (e.g., pillow, blanket, tired, bed), referred to as targets. Critical lures are items which are also associated with the lists but are intentionally omitted from study (e.g., sleep). At test, when asked to remember targets, participants often report false memories for critical lures. Findings from experiments using the DRM show the ease with which false memories develop in the absence of suggestion or misinformation. Given this, it is important to examine factors which influence the generalizability of the findings. One important factor is the persistence of false memory, or how long false memories last. Therefore, we conducted a systemic review to answer this research question: What is the persistence of false memory for specific items in the DRM paradigm? To help answer this question our review had two research objectives: (1) to examine the trajectory of target memory and false memory for critical lures and (2) to examine whether memory for targets exceeded false memory for critical lures. We included empirical articles which tested memory for the same DRM lists with at least two testing sessions. We discuss the results with respect to single-session delays, long-term memory recall and recognition, remember and know judgments for memory, and the effect of development, valence, warning, and connectivity on the trajectory of memory. Overall, the trajectory of targets showed a relatively consistent pattern of decrease across delay. The trajectory of critical lures was inconsistent. The proportion of targets versus critical lures across delay was also inconsistent. Despite the inconsistencies, we conclude that targets and critical lures have a dissimilar trajectory across delay and that critical lures are more persistent than targets. The findings with respect to long-term recall and recognition are consistent with both Fuzzy Trace Theory and Associative-Activation Theory of the DRM effect. The generation of false memory with brief delays (3-4 s) is better explained by Associative-Activation Theory. Examining the connectivity between target items, and critical lures, and the effect that has during study and retrieval, can provide insight into the persistence of false memory for critical lures.

Tracking induced forgetting across both strong and weak memory representations to test competing theories of forgetting

Here we employ a novel analysis to address the question: what causes induced forgetting of pictures? We use baseline memorability as a measure of initial memory strength to ask whether induced forgetting is due to (1) recognition practice damaging the association between the memory representation and the category cue used to activate the representation, (2) the updating of a memory trace by incorporating information about a memory probe presented during recognition practice to the stored trace, (3) inhibitory mechanisms used to resolve the conflict created when correctly selecting the practiced item activates competing exemplars, (4) a global matching model in which repeating some items will hurt memory for other items, or (5) falling into the zone of destruction, where a moderate amount of activation leads to the highest degree of forgetting. None of the accounts of forgetting tested here can comprehensively account for both the novel analyses reported here and previous data using the induced forgetting paradigm. We discuss aspects of forgetting theories that are consistent with the novel analyses and existing data, a potential solution for existing models, proposals for future directions, and considerations when incorporating memorability into models of memory.

Electrophysiological Prints of Grit

While scientific interest in understanding the grit trait has grown exponentially in recent years, one important gap in the grit literature relates to its biological and neural substrate. In the present study, we adopted a hypotheses-driven approach in a large sample of young adults (N = 120) with diverse educational backgrounds and work experiences in order to investigate the electrophysiological correlates of grit both during rest and while performing a learning task. Additionally, we selected a measure of impulsiveness to better understand the neural similarities and differences between grit and related self-control constructs. Based on previous work that implicated the prefrontal cortex in grit, we hypothesized that high grit participants would have lower frontal theta/beta ratio (a broadly used index that reflects prefrontally-mediated top-down processes, which might indicate better control over subcortical information). Furthermore, we expected the perseverance of effort facet of grit to be linked to higher complexity during task engagement because previous research has shown complexity indexes (entropy and fractal dimension) to be linked to effort while performing cognitive tasks. Our results revealed that although there were no differences at rest as a function of grit, the participants with high grit and high consistency of interest scores exhibited lower frontal theta/beta ratios during the learning task. This pattern suggests that individual differences in grit might be more evident when top-down control processes are at work. Furthermore, there was a positive association between perseverance of effort and entropy at task, which might indicate more effort and engagement in the task. Finally, no association was found between the neural indexes (frontal theta/beta ratio, entropy, or fractal dimension) and impulsiveness, neither impulsiveness mediated between grit and brain measures. Finally, when controlling for impulsiveness and demographic variables (gender, age, education, and work experience) the effects at the facet level remained statistically significant. While there is still a long way to fully understand the neural mechanisms of grit, the present work constitutes a step toward unveiling the electrophysiological prints of grit.

Relearning can eliminate the effect of retrieval-induced forgetting

The retrieval of a subset of items can cause the forgetting of other, non-retrieved items, a phenomenon known as retrieval-induced forgetting. Initial work suggested that giving people the opportunity to restudy non-retrieved items following retrieval practice is sufficient to eliminate the effect of retrieval-induced forgetting, but more recent work has suggested otherwise. If retrieval-induced forgetting is not eliminated by restudy, then such a finding would have important implications for understanding the theoretical nature of retrieval-induced forgetting. It would suggest, for example, that retrieval-induced forgetting reflects more than the temporary reduction in the accessibility of non-retrieved items in memory. The two experiments reported here sought to clarify this issue, with the results suggesting that retrieval-induced forgetting can be eliminated by restudy. Indeed, retrieval-induced forgetting was eliminated by restudy even when the forgetting effect was produced by three rounds of retrieval practice instead of one round of retrieval practice. These findings are consistent with the idea that retrieval-induced forgetting, at least under the conditions of the current experiments, reflects a temporary reduction in the accessibility of non-retrieved items in memory.

The Mechanisms Underlying Interference and Inhibition: A Review of Current Behavioral and Neuroimaging Research

The memory literature has identified interference and inhibition as two major sources of forgetting. While interference is generally considered to be a passive cause of forgetting arising from exposure to additional information that impedes subsequent recall of target information, inhibition concerns a more active and goal-directed cause of forgetting that can be achieved intentionally. Over the past 25 years, our knowledge of the neural mechanisms underlying both interference-induced and inhibition-induced forgetting has expanded substantially. The present paper gives a critical overview of this research, pointing out empirical gaps in the current work and providing suggestions for future studies.

Does a Sense of Social Presence During Conversation Affect Student's Shared Memory? Evidence From SS-RIF Paradigm

People constantly talk to one another about the past, and in so doing, they recount certain details while remaining silent about others. Collaborative or conversational remembering plays an important role in establishing shared representations of the past (e.g., the 911 attacks, Covid-19). According to the socially shared retrieval-induced forgetting (SS-RIF) effect, a listener will forget about relevant but unpracticed information during communication, due to intentional or unintentional selective retrieval of data by the speaker. The SS-RIF paradigm has been applied to explain how collective memory is shaped within the context of conversation/discourse. This study sought to determine if SS-RIF occurred only during face-to-face communication, or whether shared memories could be developed through other types of conversation quite common in modern society. We also investigated whether a level of social interaction in the real-world presence of others is a necessary condition for inducing SS-RIF, and if listeners experience different degrees of SS-RIF due to different levels of perceived social presence. We observed the SS-RIF phenomenon in listeners both in real life and video; the degree of forgetting was the same for the two conditions. These results indicate that social presence may not be associated with SS-RIF. Public silence affects the formation of collective memory regardless of the face-to-face presence of others, and thus physical presence is not necessary to induce SS-RIF.

The effect of retrieval goals on the content recalled from complex narratives

Memories are not always accurately recalled, and one factor that influences memory is the goal of retrieval. Evidence suggests that retrieving a memory to fit a social goal affects the content that is recollected, yet the nature of this effect, and whether this effect remains stable over time, is not fully understood. To this end, we compared the effect of retrieving a complex event (i.e., a narrative) motivated by a social versus an accuracy goal both immediately and after a 24-hour consolidation period. Three groups of young adults encoded audio narratives and recalled these narratives immediately (Session 1) and again after a 24-hour delay (Session 2). One group recalled the narratives to meet a social goal across both sessions (social); another group recalled the narratives for an accuracy goal across both sessions (accuracy); and a final group initially recalled the narratives for a social goal (Session 1) and then for an accuracy goal (Session 2; mixed). We found no effect of group on the number of details that described the overall theme (central details); however, a social goal significantly reduced the number of specific (episodic) details and altered the order in which the details were described. When the goal of retrieval changed across session (i.e., mixed group), the reduction in specific details remained but not the effect on detail order. These results demonstrate that socially motivated memory retrieval selectively alters the specific episodic content contained in the memory, leaving intact the thematic knowledge and overall structure of the memory.

The relative contribution of shape and colour to object memory

The current studies examined the relative contribution of shape and colour in object representations in memory. A great deal of evidence points to the significance of shape in object recognition, with the role of colour being instrumental under certain circumstances. A key but yet unanswered question concerns the contribution of colour relative to shape in mediating retrieval of object representations from memory. Two experiments (N=80) used a new method to probe episodic memory for objects and revealed the relative contribution of colour and shape in recognition memory. Participants viewed pictures of objects from different categories, presented one at a time. During a practice phase, participants performed yes/no recognition with some of the studied objects and their distractors. Unpractised objects shared shape only (Rp–Shape), colour only (Rp–Colour), shape and colour (Rp–Both), or neither shape nor colour (Rp–Neither), with the practised objects. Interference effects in memory between practised and unpractised items were revealed in the forgetting of related unpractised items – retrieval-induced forgetting. Retrieval-induced forgetting was consistently significant for Rp–Shape and Rp–Colour objects. These findings provide converging evidence that colour is an automatically encoded object property, and present new evidence that both shape and colour act simultaneously and effectively to drive retrieval of objects from long-term memory.

Resurrected memories: Sleep-dependent memory consolidation saves memories from competition induced by retrieval practice

Retrieval practice improves retention of tested information, and it can either impair or facilitate retention of untested information. Here, we investigated how semantic relatedness, episodic context, and sleep-dependent memory consolidation determine the effects of retrieval practice on retention of untested items. Participants studied lists of scene-word associations. Each scene was associated with two different words (“pairmates”) that were either semantically related or unrelated and either in the same (temporally close) or different lists (temporally far). In three experiments, retrieval practice of scene-word associations facilitated retention of unpracticed, temporally close pairmates and impaired retention of temporally far, semantically unrelated pairmates. Critically, retrieval practice impaired retention of temporally far, semantically related pairmates if participants were unable to sleep during the retention interval, but it facilitated retention of these items if participants were able to sleep. Our findings suggest that sleep extends the benefits of testing to related information learned in temporally separate episodes.

List-method directed forgetting: Do critical findings generalize from short to long retention intervals?

People can purposefully forget information that has become irrelevant, as is demonstrated in list-method directed forgetting (LMDF). In this task, participants are cued to intentionally forget an already studied list (list 1) before encoding a second list (list 2); this induces forgetting of the first-list items. Most research on LMDF has been conducted with short retention intervals, but very recent studies indicate that such directed forgetting can be lasting. We examined in two experiments whether core findings in the LMDF literature generalize from short to long retention intervals. The focus of Experiment 1 was on the previous finding that, with short retention interval, list-2 encoding is necessary for list-1 forgetting to arise. Experiment 1 replicated the finding after a short delay of 3 min between study and test and extended it to a longer delay of 20 min. The focus of Experiment 1 was on the absence of list-1 forgetting in item recognition, previously observed after short retention interval. Experiment 1 replicated the finding after a short delay of 3 min between study and test and extended it to longer delays of 20 min and 24 h. Implications of the results for theoretical explanations of LMDF are discussed.

Accessibility and Historical Change: An Emergent Cluster Led Uncles and Aunts to Become Aunts and Uncles

There are times when a curiously odd relic of language presents us with a thread, which when pulled, reveals deep and general facts about human language. This paper unspools such a case. Prior to 1930, English speakers uniformly preferred male-before-female word order in conjoined nouns such as uncles and aunts; nephews and nieces; men and women. Since then, at least a half dozen items have systematically reversed their preferred order (e.g., aunts and uncles, nieces and nephews) while others have not (men and women). We review evidence that the unusual reversals began with mother and dad(dy) and spread to semantically and morphologically related binomials over a period of decades. The present work proposes that three aspects of cognitive accessibility combine to quantify the probability of A&B order: (1) the relative accessibility of the A&B terms individually, (2) competition from B&A order, and critically, (3) cluster strength (i.e., similarity to related A'&B' cases). The emergent cluster of female-first binomials highlights the influence of semantic neighborhoods in memory retrieval. We suggest that cognitive accessibility can be used to predict the word order of both familiar and novel binomials generally, as well as the diachronic change focused on here.

Oscillatory Correlates of Selective Restudy

Prior behavioral work has shown that selective restudy of some studied items leaves recall of the other studied items unaffected when lag between study and restudy is short, but improves recall of the other items when lag is prolonged. The beneficial effect has been attributed to context retrieval, assuming that selective restudy reactivates the context at study and thus provides a retrieval cue for the other items (Bäuml, 2019). Here the results of two experiments are reported, in each of which subjects studied a list of items and then, after a short 2-min or a prolonged 10-min lag, restudied some of the list items. Participants' electroencephalography (EEG) was recorded during both the study and restudy phases. In Experiment 2, but not in Experiment 1, subjects engaged in a mental context reinstatement task immediately before the restudy phase started, trying to mentally reinstate the study context. Results of Experiment 1 revealed a theta/alpha power increase from study to restudy after short lag and an alpha/beta power decrease after long lag. Engagement in the mental context reinstatement task in Experiment 2 eliminated the decrease in alpha/beta power. The results are consistent with the view that the observed alpha/beta decrease reflects context retrieval, which became obsolete when there was preceding mental context reinstatement.

Medium strength visual long-term memories are the most fragile

What memories do humans forget? One theory proposes that memories stored with moderate activation levels are weakened when faced with competitive stress so that they are particularly prone to be forgotten. However, research suggests that visual long-term memories are stronger than memories of other modalities, and therefore may never fall into this moderate activation zone. Here we tested these competing predictions by showing to-be-remembered pictures while we recorded event-related potentials (ERPs) indexing memory activation during encoding. We found that visual memories with medium levels of activation when first encoded were more prone to forgetting than memories with high or low encoding activation levels, but this only occurred if a memory was faced with competition. This study shows that we forget moderately activated memories when they are subjected to competition, regardless of the modality of experience.

Cumulative semantic cost without successful naming

Accessing semantic information has negative consequences for successive recovering attempts of similar information. For instance, in the course of picture-naming tasks, the time required to name an object is determined by the total number of items from the same category that have already been named; naming latencies increase proportionally to the total number of semantically related words named previously. This phenomenon is called cumulative semantic cost (or interference). Two picture-naming experiments with children (4–11 years old, 229 participants) investigate whether having successfully named the previous within-category items is a necessary condition for the cumulative semantic cost to appear. We anticipated that younger children would have a larger rate of nonresponses compared with older children, reflecting the fact that younger children have not yet consolidated many lexical representations. Our results confirmed this prediction. Critically, we also observed that cumulative semantic cost was independent of having successfully retrieved previous within-category lexical items. Furthermore, picture trials for which the previous within-category item elicited a nonresponse showed the same amount of cost as those picture trials for which the previous within-category item elicited a correct naming event. Our findings indicate that it is the attempt to retrieve a lexical unit, and not the successful retrieval of a specific lexical unit, that causes semantic cost in picture naming. This cost can be explained by a mechanism of weakening the semantic-to-lexical mappings of semantic coordinate words. The findings are also discussed in the context of retrieval-induced forgetting effects in memory recall research.

Delving Into the Working Mechanism of Prediction in Sentence Comprehension: An ERP Study

The present study aims to delineate the working mechanism of prediction in sentence comprehension, by disentangling the influence of the facilitated general memory retrieval from the coexistent influence of the predicted language-specific semantic and/or syntactic information for the first time. The results support that prediction might influence the downstream cognitive processing in two aspects: (1) the pre-activated information facilitates the retrieval of a matched input in memory and, (2) the pre-activated information interacts with higher-level semantic/syntactic processing. More importantly, the present findings suggest that these two types of influences seem to occur at different stages of sentence comprehension: the facilitated memory retrieval of the input modulates N400 amplitude and the latency of post-N400 late central-parietal positivity/P600, while the predicted semantic/syntactic information and/or their interactions modulate the amplitude of the late positivity. The present findings would be helpful for interpreting the underlying mechanism of observed effects in prediction studies.

Selective attention to stimulus representations in perception and memory: commonalities and differences

It has been proposed that the deployment of selective attention to perceptual and memory representations might be governed by similar cognitive processes and neural resources. However, evidence for this simple and appealing proposal remains inconclusive, which might be due to a considerable divergence in tasks and cognitive demands when comparing attentional selection in memory versus perception. To examine whether selection in both domains share common attentional processes and only differ in the stimuli they act upon (external vs. internal), we compared behavioral costs or benefits between selection domains. In both domains, participants had to attend a target stimulus from a set of simultaneously presented stimuli or simultaneously active memory representations, respectively, with set, target, or both, being repeated or changed across trials. The results of two experiments delineated principal similarities and differences of selection processes in both domains: While positive priming from stimulus repetition was found in both selection domains, we found no consistent effects of negative priming when shifting the focus of attention to a previously to-be-ignored stimulus. However, priming in the perception task was mainly due to repetitions of the target feature (here: color), whereas for the memory task, repetition of the same set of stimulus representations was most important. We propose that the differences can be attributed to a reduced cognitive effort when the now relevant memory representation had already been pre-activated (even as a distractor) in the previous trial. Additionally, our experiments both underscore the importance of taking stimulus-response associations into account, which may be a hidden factor behind differences between domains. We conclude that any attempt of comparing internal versus external attentional selection has to consider inherent differences in selection dynamics across representational domains.

Recognition-induced forgetting is caused by episodic, not semantic, memory retrieval tasks

Recognition-induced forgetting is a within-category forgetting effect that results from accessing memory representations. Advantages of this paradigm include the possibility of testing the memory of young children using visual objects before they can read, the testing of multiple types of stimuli, and use with animal models. Yet it is unknown whether just episodic memory tasks (Have you seen this before?) or also semantic memory tasks (Is this bigger than a loaf of bread?) will lead to this forgetting effect. This distinction will be critical in establishing a model of recognition-induced forgetting. Here, we implemented a design in which both these tasks were used in the same experiment to determine which was leading to recognition-induced forgetting. We found that episodic memory tasks, but not semantic memory tasks, created within-category forgetting. These results show that the difference-of-Gaussian forgetting function of recognition-induced forgetting is triggered by episodic memory tasks and is not driven by the same underlying memory signal as semantic memory.

Recognition-induced forgetting of schematically related pictures

Recognition-induced forgetting is the category-specific forgetting of pictures that occurs when a subset of a category of pictures is recognized, leading to forgetting of the remaining pictures. We have previously shown that recognition-induced forgetting does not operate over categories created by temporal relationships, suggesting that this effect does not operate over episodic memory representations. Here we systematically tested whether schematically related categories of pictures are immune to recognition-induced forgetting. We found that sufficiently weak schematically related memories are vulnerable to recognition-induced forgetting. These results offer an alternative interpretation for evidence that recognition-induced forgetting does not operate over episodic memory representations. Evidence that the strength of schematic grouping modulates forgetting supports a model of recognition-induced forgetting in which the key determinant of forgetting is moderate activation. This is the first demonstration that recognition-induced forgetting operates over perceptually distinct objects, demonstrating the ubiquity of such forgetting.

Part-List Cues Hinder Familiarity but Not Recollection in Item Recognition: Behavioral and Event-Related Potential Evidence

Participants' memory performance is normally poorer when a subset of previously learned items is provided as retrieval cues than none of the retrieval cues is provided. This phenomenon is called the part-list cuing effect, which has been discovered in numerous behavioral studies. However, there is currently no relevant behavioral or event-related potential (ERP) research to investigate whether the forgetting effect caused by part-list cues is more sensitive to recollection or to familiarity. By combining the part-list cuing paradigm with the Remember/Know procedure, we investigated this issue in the present ERP study. Behavioral data showed part-list cuing induced detrimental effect in two aspects: significantly lowered familiarity of the target items and decreased memory discrimination score (P_r score) for "Know" but not for "Remember" items in the part-list cue condition than in the no-part-list cue condition. ERP data revealed that the FN400 old/new effects, which are associated with familiarity, were absent when providing part-list cues, whereas the late positive complex (LPC) old/new effects, which are associated with recollection, were observed comparably in both part-list cue and no-part-list cue conditions. Converging behavioral and ERP results suggested that part-list cues hindered familiarity-based retrieval but not recollection-based retrieval of item recognition. Theoretical implications of the findings for the part-list cuing effect are discussed.

Expert Event Segmentation of Dance Is Genre-Specific and Primes Verbal Memory

By chunking continuous streams of action into ordered, discrete, and meaningful units, event segmentation facilitates motor learning. While expertise in the observed repertoire reduces the frequency of event borders, generalization of this effect to unfamiliar genres of dance and among other sensorimotor experts (musicians, athletes) remains unknown, and was the first aim of this study. Due to significant overlap in visuomotor, language, and memory processing brain networks, the second aim of this study was to investigate whether visually priming expert motor schemas improves memory for words related to one’s expertise. A total of 112 participants in six groups (ballet, Bharatanatyam, and “other” dancers, athletes, musicians, and non-experts) segmented a ballet dance, a Bharatanatyam dance, and a non-dance control sequence. To test verbal memory, participants performed a retrieval-induced forgetting task between segmentation blocks. Dance, instrument, and sport word categories were included to probe the second study aim. Results of the event segmentation paradigm clarify that previously-established expert segmentation effects are specific to familiar genres of dance, and do not transfer between different types of experts or to non-dance sequences. Greater recall of dance category words among ballet and Bharatanatyam dancers provides novel evidence for improved verbal memory primed by activating familiar sensorimotor representations.

Decisions bias future choices by modifying hippocampal associative memories

Decision-making is guided by memories of option values. However, retrieving items from memory renders them malleable. Here, we show that merely retrieving values from memory and making a choice between options is sufficient both to induce changes to stimulus-reward associations in the hippocampus and to bias future decision-making. After allowing participants to make repeated choices between reward-conditioned stimuli, in the absence of any outcome, we observe that participants prefer stimuli they have previously chosen, and neglect previously unchosen stimuli, over otherwise identical-valued options. Using functional brain imaging, we show that decisions induce changes to hippocampal representations of stimulus-outcome associations. These changes are correlated with future decision biases. Our results indicate that choice-induced preference changes are partially driven by choice-induced modification of memory representations and suggest that merely making a choice - even without experiencing any outcomes - induces associative plasticity.

Serial dependence in vision: Merely encoding the previous-trial target is not enough

The reported perception of a visual stimulus on one trial can be biased by the stimulus that was presented on the previous trial. In the present study we asked whether encoding the previous-trial stimulus is sufficient to produce this serial dependence effect, or whether the effect also depends on postencoding processes. To distinguish between these possibilities, we designed a task in which participants reported either the color or the direction of a set of colored moving dots on each trial. The to-be-reported dimension was indicated by a postcue after stimulus offset, so participants were required to encode both features of every stimulus. We assessed serial dependence for motion perception as a function of which feature dimension had been reported on the previous trial. In Experiment 1, we found a serial dependence effect for motion only when participants had reported the direction of motion on the previous trial, and not when they had encoded the direction of motion but reported the color of the stimulus. Experiment 2 confirmed that this pattern of results was not driven by the difficulty of the color task. When we used the same response modality for both motion and color reports in Experiment 3, we found significant serial dependence effects following both color-report and motion-report trials, but the effect was significantly weaker following color-report trials. Together, these findings indicate that postperceptual processes play a critical role in serial dependence and that the mere encoding of the previous-trial target is not sufficient to produce the serial dependence effect.

Category labels can influence the effects of selective retrieval on nonretrieved items

Using lists of unrelated items as study material, recent studies have shown that selective retrieval of some studied items can impair or improve recall of the nonretrieved items, depending on whether the lag between study and selective retrieval is short or long. This study examined whether the results generalize when the items are studied together with their category labels (e.g., BIRD-magpie) and the category labels are reexposed as retrieval cues at test (e.g., BIRD-m___), a procedure often used in research on the effects of selective retrieval. Two lag conditions were employed in this study: a short 1-min lag between study and selective retrieval, and a longer 15-min lag that included mental context change tasks to enhance the lag-induced contextual drift. Experiment 1 employed lists of unrelated items in the absence of any category labels and replicated both the detrimental effect (after short lag) and the beneficial effect (after long lag) of selective retrieval. Experiment 1 was identical to Experiment 1 but provided the items' category labels during both study and retrieval, and Experiment 1 was identical to Experiment 1 but employed a categorized list. In both experiments, selective retrieval impaired recall in both lag conditions, indicating a critical role of category labels for the effects of selective retrieval. The results of the three experiments are consistent with a two-factor explanation of selective retrieval and the proposal that reexposure of category labels during retrieval can reinstate study context after longer lag.

Does retrieving a memory insulate it against memory inhibition? A retroactive interference study

Several recent studies suggest that an initial retrieval attempt imbues retrieved memories with special resilience against future interference and other forgetting mechanisms. Here we report two experiments examining whether memories established through initial retrieval remain subject to retrieval-induced forgetting. Using a version of a classical retroactive interference design, we trained participants on a list of A-B pairs via anticipation - constituting a form of retrieval practice. After next training participants on interfering A-C pairs, they performed 0-12 additional A-C anticipation trials. Because these trials required retrieval of A-C pairs, they should function similarly to retrieval practice in paradigms establishing retrieval-induced forgetting. We observed robust evidence that retroactive interference generalises to final memory tests involving novel, independent memory probes. Moreover, in contrast to practising retrieval of A-C items, their extra study failed to induce cue-independent forgetting of the original B items. Together, these findings substantiate the role of retrieval-related inhibitory processes in a traditional retroactive interference design. Importantly, they indicate that an initial retrieval attempt on a competitor does not abolish retrieval-induced forgetting, at least not in the context of this classic design. Although such an attempt may protect against inhibition in some circumstances, the nature of those circumstances remains to be understood.

Do reminders of the crime reverse the memory-undermining effect of simulating amnesia?

Research shows that simulating amnesia impairs actual memory for a mock crime. Lack of rehearsal has been suggested as the most likely explanation for this finding because feigning amnesia is linked to reduced thinking about the offence. We investigated whether reminders about the crime could reverse the memory-undermining effect of simulation. In two studies, participants watched a video of a violent crime. After, they were asked to either simulate amnesia or confess the crime. During the week between the first and second memory test phase, participants were provided with reminders of the crime in two different modalities. In Study 1 (pilot), participants received frames of the mock crime video via WhatsApp. Findings showed that such reminders did not enhance ex-simulators' memory. In Study 2, participants were asked to put sequences of the mock crime in the right order. This latter modality led to enhanced memory for the offence in simulating participants. Theoretical and practical implications of our findings for the legal field are discussed.

Modality-specific forgetting

A large body of literature agrees that accessing a target memory appears to trigger a difference-of-Gaussian memory activation pulse under which the target representation is activated and categorically flanking items are suppressed and forgotten. The nature of the underlying forgetting mechanism is far from settled, with support for several theories of forgetting. Here we argue the debate is partly fueled by different forgetting mechanisms underlying the forgetting of different memoranda. We capitalized on the unique aspect of the recognition-induced forgetting paradigm to test forgetting of both pictures and words in identical recognition-practice and restudy tasks. We found that memory for pictures and words followed different patterns of forgetting. Specifically, forgetting was retrieval specific for words, in that forgetting occurred only when words were recognized, and not when words were merely restudied. However, forgetting was not retrieval specific for pictures, in that forgetting occurred both when pictures were recognized as well as restudied. Further, patterns of forgetting operated along different category-level groupings for pictures and words. Words grouped along the superordinate level were susceptible to forgetting but pictures were not. The strength of this design is the ability to directly compare forgetting for different memoranda, establishing that patterns of forgetting are modality specific. These findings demonstrate that the mechanisms underlying forgetting may differ as a function of the particular memoranda, emphasizing the need for examining forgetting in long-term memory across modalities.

Unintentional forgetting is beyond cognitive control

Intentional forgetting refers to the attempt to marshal top-down control to purposefully forget, and has been demonstrated in the laboratory using directed forgetting paradigms. Here, we asked whether the mechanisms of top-down control can run in the opposite direction to prevent the forgetting of information; that is, can we actively resist unintentional forgetting? Recognition-induced forgetting is an unintentional forgetting effect in which accessing one memory leads to the forgetting of related memories. Just as intentional forgetting possesses intuitively appealing control over eliminating undesirable memories, resisting unintentional forgetting over desired memories would improve cognitive performance. We showed subjects a 9-min video to teach them about the recognition-induced forgetting paradigm and how recognition of certain objects unintentionally leads to forgetting of semantically related objects. After testing their comprehension of the video, we conducted a typical recognition-induced forgetting experiment and challenged the subjects to resist this form of unintentional forgetting. Despite their knowledge of the forgetting effect, and the challenge to subjects to resist the forgetting induced by the paradigm, recognition-induced forgetting persisted. These results show that knowledge of this unintentional forgetting phenomenon and the challenge to resist forgetting do not eliminate it, suggesting that it is cognitively impenetrable.

Retrieval-induced forgetting in a social context: Do the same mechanisms underlie forgetting in speakers and listeners?

Selectively retrieving details from memory can result in forgetting related information, a finding known as retrieval-induced forgetting (RIF). The effect has mostly been examined in individuals, but RIF can also be socially transmitted and arise in listeners who are exposed to a speaker's selective memory retrieval. Whether within-individual RIF (WI-RIF) in speakers and socially shared RIF (SS-RIF) in listeners arise on the basis of the same cognitive mechanisms is unclear, however. In four experiments, we assessed both WI-RIF and SS-RIF while varying final test format to examine the potential involvement of output interference, strength-based blocking, and inhibition. WI-RIF and, to a similar degree, SS-RIF were observed on cued-recall tests with and without controlled output order at test, indicating that output interference cannot account for the observed forgetting. In contrast, SS-RIF was reduced relative to WI-RIF on tests of item recognition. These findings are consistent with the view that inhibition and blocking contribute to both WI-RIF and SS-RIF, but that the contribution of inhibition is reduced in listeners relative to speakers.

Theta oscillations show impaired interference detection in older adults during selective memory retrieval

Seemingly effortless tasks, such as recognizing faces and retrieving names, become harder as we age. Such difficulties may be due to the competition generated in memory by irrelevant information that comes to mind when trying to recall a specific face or name. It is unknown, however, whether age-related struggles in retrieving these representations stem from an inability to detect competition in the first place, or from being unable to suppress competing information once interference is detected. To investigate this, we used the retrieval practice paradigm, shown to elicit memory interference, while recording electrophysiological activity in young and older adults. In two experiments, young participants showed Retrieval-Induced Forgetting (RIF), reflecting the suppression of competing information, whereas older adults did not. Neurally, mid-frontal theta power (~4-8 Hz) during the first retrieval cycle, a proxy for interference detection, increased in young compared to older adults, indicating older adults were less capable of detecting interference. Moreover, while theta power was reduced across practice cycles in younger adults, a measure of interference resolution, older adults did not show such a reduction. Thus, in contrast with younger adults, the lack of an early interference detection signal rendered older adults unable to recruit memory selection mechanisms, eliminating RIF.

Verbal Learning and Memory After Cochlear Implantation in Postlingually Deaf Adults: Some New Findings with the CVLT-II

OBJECTIVES

Despite the importance of verbal learning and memory in speech and language processing, this domain of cognitive functioning has been virtually ignored in clinical studies of hearing loss and cochlear implants in both adults and children. In this article, we report the results of two studies that used a newly developed visually based version of the California Verbal Learning Test-Second Edition (CVLT-II), a well-known normed neuropsychological measure of verbal learning and memory.

DESIGN

The first study established the validity and feasibility of a computer-controlled visual version of the CVLT-II, which eliminates the effects of audibility of spoken stimuli, in groups of young normal-hearing and older normal-hearing (ONH) adults. A second study was then carried out using the visual CVLT-II format with a group of older postlingually deaf experienced cochlear implant (ECI) users (N = 25) and a group of ONH controls (N = 25) who were matched to ECI users for age, socioeconomic status, and nonverbal IQ. In addition to the visual CVLT-II, subjects provided data on demographics, hearing history, nonverbal IQ, reading fluency, vocabulary, and short-term memory span for visually presented digits. ECI participants were also tested for speech recognition in quiet.

RESULTS

The ECI and ONH groups did not differ on most measures of verbal learning and memory obtained with the visual CVLT-II, but deficits were identified in ECI participants that were related to recency recall, the buildup of proactive interference, and retrieval-induced forgetting. Within the ECI group, nonverbal fluid IQ, reading fluency, and resistance to the buildup of proactive interference from the CVLT-II consistently predicted better speech recognition outcomes.

CONCLUSIONS

Results from this study suggest that several underlying foundational neurocognitive abilities are related to core speech perception outcomes after implantation in older adults. Implications of these findings for explaining individual differences and variability and predicting speech recognition outcomes after implantation are discussed.

Recognition-induced forgetting does not occur for temporally grouped objects unless they are semantically related

Recent evidence has shown that practice recognizing certain objects hurts memories of objects from the same category, a phenomenon called recognition-induced forgetting. In all previous studies of this effect, the objects have been related by semantic category (e.g., instances of vases). However, the relationship between objects in many real-world visual situations stresses temporal grouping rather than semantic relations (e.g., a weapon and getaway car at a crime scene), and temporal grouping is thought to cluster items in models of long-term memory. The goal of the present study was to determine whether temporally grouped objects suffer recognition-induced forgetting. To this end, we implemented a modified recognition-induced forgetting paradigm in which the objects were temporally clustered at study. Across four experiments, we found that recognition-induced forgetting occurred only when the temporally clustered objects were also semantically related. We conclude by discussing how these findings relate to real-world vision and inform models of memory.

Inhibitory control during selective retrieval may hinder subsequent analogical thinking

Analogical reasoning is a complex cognitive activity that involves access and retrieval of pre-existing knowledge in order to find a suitable solution. Prior work has shown that analogical transfer and reasoning can be influenced by unconscious activation of relevant information. Based on this idea, we report two experiments that examine whether reduced access to relevant information in memory may further disrupt analogical reasoning unwittingly. In both experiments, we use an adaptation of the retrieval practice paradigm [1] to modulate memory accessibility of potential solutions to a subsequent set of analogy problems of the type 'A is to B as C is to ?'. Experiment 1 showed a retrieval-induced impairment in analogical problem solving. Experiment 2 replicated this finding and demonstrated that it cannot be due to the deliberative episodic retrieval of the solutions to the analogies. These findings, predictable from an inhibitory framework of memory control, provide a new focus for theories of analogical transfer and highlight the importance of unconscious memory processes that may modulate problem solving.

Feedback increases benefits but not costs of retrieval practice: Retrieval-induced forgetting is strength independent

We examined how the provision of feedback affected two separate effects of retrieval practice: strengthening of practiced information and forgetting of related, unpracticed information. Feedback substantially increased recall of retrieval-practiced items. This unsurprising result shows once again that restudy opportunities boost the benefits of testing. In contrast, retrieval-induced forgetting was unaffected by the manipulation and occurred in equal size with or without feedback. These findings demonstrate strength independence of retrieval-induced forgetting and thus support a theoretical account assuming that an inhibitory mechanism causes retrieval-induced forgetting. According to this theory, inhibition resolves competition that arises during retrieval attempts but is unrelated to the consequences of retrieval practice concerning practiced items. The present results match these assumptions and contradict the theoretical alternative that blocking by strengthened information might explain retrieval-induced forgetting. We discuss our findings against the background of previous studies.

Improving Memory Inhibition: A Study of Retrieval Induced Forgetting, Executive Control, and Chronic Aerobic Exercise

Chronic aerobic exercise is being established as a way to enhance executive functions and prevent cognitive decline. In the current study, we are aiming to investigate whether chronic aerobic exercise would also modulate long-term memory retrieval under the context of the Retrieval Practice Paradigm. According to Anderson et al. (1994), the retrieval of relevant information may decrease the access to other related information inducing the failure to remember or forgetting Interestingly, it has been shown (Román et al., 2009) that this process is mediated by the level of attentional resources. In order to test if chronic aerobic exercise benefits attentional resources, we have applied the Dual Retrieval Practice Task. The purpose of this task is to evaluate the Retrieval Induced Forgetting (RIF) effect, which is supposed to index adaptive forgetting. More specifically, the Dual Retrieval Practice Task assesses the effects of memory retrieval on forgetting information directly related to the information that has been previously retrieved, but also studies the involvement of attentional resources on this type of forgetting (retrieval induced forgetting). This task alternates memory retrieval practice with an updating task in order to load attentional resources. Two groups of physically active and sedentary young participants were evaluated. The results showed that while active participants were able to show RIF despite the overload of the attentional resources, sedentary participants were not. These results are discussed in terms of the modulatory role of chronic aerobic exercise on executive control and retrieval induced forgetting.

Retrieval-Induced Forgetting in a Pentylenetetrazole-Induced Epilepsy Model in the Rat

The selective retrieval of some information may lead to the forgetting of related, but non-retrieved information. This memory phenomenon is termed retrieval-induced forgetting (RIF). Active inhibition is thought to function to resolve interference from competing information during retrieval, which results in forgetting. Epilepsy is associated with impaired inhibitory control that contributes to executive dysfunction. The purpose of this study is to investigate whether rats in a kindling model of epilepsy demonstrate normal levels of RIF. Rats were divided into two groups: saline and kindling. Pentylenetetrazole was injected intraperitoneally until the rats kindled. RIF was tested using a modified version of the spontaneous object recognition test, consisting of a sample phase, retrieval or interference phase, and a test phase. Exploration time for each object was analyzed. RIF was demonstrated in the saline group when rats subjected to the retrieval phase failed to discriminate between the familiar object and the novel object later in the test phase. Kindled rats, on the other hand, did not suffer forgetting even when they were subjected to the retrieval phase, as they spent significantly longer times exploring the novel rather than the familiar object in the test phase. Therefore, RIF was not observed in the kindling group. These findings indicate impaired retrieval-induced forgetting in kindled rats, which may be suggestive of a deficit in the inhibitory control of memory.

A retrieval-specific mechanism of adaptive forgetting in the mammalian brain

Forgetting is a ubiquitous phenomenon that is actively promoted in many species. How and whether organisms’ behavioral goals drive which memories are actively forgotten is unknown. Here we show that processes essential to controlling goal-directed behavior trigger active forgetting of distracting memories that interfere with behavioral goals. When rats need to retrieve particular memories to guide exploration, it reduces later retention of other memories encoded in that environment. As with humans, this retrieval-induced forgetting is competition-dependent, cue-independent and reliant on prefrontal control: Silencing the medial prefrontal cortex with muscimol abolishes the effect. cFos imaging reveals that prefrontal control demands decline over repeated retrievals as competing memories are forgotten successfully, revealing a key adaptive benefit of forgetting. Occurring in 88% of the rats studied, this finding establishes a robust model of how adaptive forgetting harmonizes memory with behavioral demands, permitting isolation of its circuit, cellular and molecular mechanisms.

Forgetting is ubiquitous across the animal kingdom, but neuroscience is only beginning to address its mechanisms. This study shows that rats, like humans, actively forget memories that interfere with retrieval, and that this retrieval-induced forgetting requires the prefrontal cortex.

Memory and availability-biased metacognitive illusions for flags of varying familiarity

Research on everyday attention suggests that frequent interaction with objects often does not benefit memory or metamemory for them. Across three experiments, participants gave confidence judgments and completed eight-alternative forced-choice tests of the US, Canadian, and Mexican flags. In Experiment 1, environmental availability was correlated with confidence for the US flag, despite similar recognition performance at a saturated time point in the US (July 4th) and a neutral time point (August 6th). In Experiment 2, participants that were asked to verbally describe the flags before judging and remembering them were less accurate and more overconfident than were controls. Experiment 3 utilized a draw-study paradigm wherein participants who first drew the flag had reliably more accurate recognition and confidence scores than those who only studied it. These findings illuminate a persistent metacognitive bias, demonstrate a powerful learning intervention, and extend theories of errorful learning by highlighting the role of attention.

Retrieval-Induced Forgetting as Motivated Cognition

Recalling information from a particular category can reduce one’s memory capability for related, non-retrieved information. This is known as the retrieval-induced forgetting effect (RIF; Anderson et al., 1994). The present paper reviews studies that show that the RIF effect is motivated. More specifically, we describe research showing that the need for closure (NFC; the motivation to attain epistemic certainty; Kruglanski and Webster, 1996) generally enhances the RIF, because this prevents uncertainty and confusion from the intrusion of unwanted memories during selective-retrieval. However, when the content of the to-be-forgotten information serves the retriever’s goals, NFC reduces RIF. Overall, the present findings are consistent with the view that motivation can affect the magnitude of RIF effects which, in turn, can serve as a mechanism for reaching preferred conclusions.