Directed forgetting shares mechanisms with attentional withdrawal but not with stop-signal inhibition

The role of prior familiarisation and meaningfulness of verbal and visual stimuli on directed forgetting

ABSTRACTIntentional forgetting of unwanted information is a crucial cognitive function that is often studied with directed forgetting (DF) procedure, whereby cuing some study materials with Forget (F) instruction impairs their memory compared to cuing with Remember (R) instruction. This study investigates how the nature of information (verbal or pictorial), its semantic significance (meaningful or meaningless), and the degree of prior episodic familiarity influence DF. Before the DF phase, stimuli were familiarised by pre-exposing them 0, 2, or 6 times in a prior preview phase. Finally, memory for all items was assessed with old/new recognition test. Experiment 1 employed words, Experiment 2 utilised fractal images, Experiment 3 featured both meaningful and meaningless object images, and Experiment 4 used words and nonwords. Our results indicate that materials that produced better memory performance are not always harder to intentionally forget. Previewed items showed reduced DF compared to non-previewed items regardless of the nature of information, and meaningless stimuli are challenging to intentionally forget regardless of their degrees of familiarisation unless they are meaningless verbal materials. Collectively, the results highlight the importance of joint consideration of the stimulus format, its meaningfulness, and its episodic familiarity in understanding conditions that interact with intentional forgetting.

A computational account of item-based directed forgetting for nonwords: Incorporating orthographic representations in MINERVA 2

Recent research on item-method directed forgetting demonstrates that forget instructions not only decrease recognition for targets, but also decrease false recognition for foils from the same semantic categories as targets instructed to be forgotten. According to the selective rehearsal account of directed forgetting, this finding suggests that remember instructions may engage elaborative rehearsal of the category-level information of items. In contrast to this explanation, Reid and Jamieson (Canadian Journal of Experimental Psychology / Revue canadienne de psychologie expérimentale, 76(2), 75-86, 2022) proposed that the differential rates of false recognition may emerge at retrieval when foils from "remember" and "forget" categories are compared to traces in memory. Using MINERVA S, an instance model of memory based on MINERVA 2 that incorporates structured semantic representations, Reid and Jamieson successfully simulated lower false recognition for foils from "forget" categories without assuming rehearsal of category-level information. In this study, we extend the directed forgetting paradigm to categories consisting of orthographically related nonwords. Presumably participants would have difficulty rehearsing category-level information for these items because they would have no pre-experimental knowledge of these categories. To simulate the findings in MINERVA S, we imported structured orthographic representations rather than semantic representations. The model not only predicted differential rates of false recognition for foils from "remember" and "forget" categories, but also predicted higher rates of false recognition overall than what was observed for semantic categories. The empirical data closely matched these predictions. These data suggest that differential rates of false recognition due to remember and forget instructions emerge at retrieval when participants compare recognition probes to traces stored in memory.

Let me give you something to think about: Does needing to remember something new make it easier to forget something old?

In an item-method directed forgetting task, memory instructions presumably operate by promoting further rehearsal of to-be-remembered (TBR) items and limiting encoding of to-be-forgotten (TBF) items. We asked whether diverting attentional resources away from TBF items and towards a new item that needed to be committed to memory would improve forgetting. To this end, study words in our experiments were presented singly followed by a remember instruction (single-TBR), by a forget instruction (single-TBF), or else were replaced by a new word to be remembered (replace-TBR) in place of the original study word which could be forgotten (replace-TBF). A typical directed forgetting effect was observed across single and replace trials. However, there was no compelling evidence that forgetting was better for replace-TBF compared to single-TBF words, suggesting that, by itself, the explicit redirection of attentional and other processing resources away from forget items may not be sufficient to improve item-method directed forgetting.

Differential Recruitment of Inhibitory Control Processes by Directed Forgetting and Thought Substitution

Humans have the ability to intentionally forget information via different strategies, included suppression of encoding (directed forgetting) and mental replacement of the item to encode (thought substitution). These strategies may rely on different neural mechanisms; namely, encoding suppression may induce prefrontally mediated inhibition, whereas thought substitution is potentially accomplished through modulating contextual representations. Yet, few studies have directly related inhibitory processing to encoding suppression, or tested its involvement in thought substitution. Here, we directly tested whether encoding suppression recruits inhibitory mechanisms with a cross-task design, relating the behavioral and neural data from male and female participants in a Stop Signal task (a task specifically testing inhibitory processing) to a directed forgetting task with both encoding suppression (Forget) and thought substitution (Imagine) cues. Behaviorally, Stop Signal task performance (stop signal reaction times) was related to the magnitude of encoding suppression, but not thought substitution. Two complementary neural analyses corroborated the behavioral result. Namely, brain-behavior analysis demonstrated that the magnitude of right-frontal beta activity following stop signals was related to stop signal reaction times and successful encoding suppression, but not thought substitution; and classifiers trained to discriminate successful and unsuccessful stopping in the Stop Signal task could also classify successful and unsuccessful forgetting following Forget cues, but not Imagine cues. Importantly, inhibitory neural mechanisms were engaged following Forget cues at a later time than motor stopping. These findings not only support an inhibitory account of directed forgetting, and that thought substitution engages separate mechanisms, but also potentially identify a specific time in which inhibition occurs when suppressing encoding.SIGNIFICANCE STATEMENT Forgetting often seems like an unintended experience, but forgetting can be intentional, and can be accomplished with multiple strategies. These strategies, including encoding suppression and thought substitution, may rely on different neural mechanisms. Here, we test the hypothesis that encoding suppression engages domain-general prefrontally driven inhibitory control mechanisms, while thought substitution does not. Using cross-task analyses, we provide evidence that encoding suppression engages the same inhibitory mechanisms used for stopping motor actions, but these mechanisms are not engaged by thought substitution. These findings not only support the notion that mnemonic encoding processes can be directly inhibited, but also have broad relevance, as certain populations with disrupted inhibitory processing may be more successful accomplishing intentional forgetting through thought substitution strategies.

Selective remembering and directed forgetting are influenced by similar stimulus properties

Do the properties of to-be-remembered events influence the ability to remember, and also intentionally forget, these events in similar ways? Prior work has examined how the font size, animacy, emotionality, concreteness (the degree to which a word denotes something perceptible), frequency (how often a word appears in language), and length of to-be-remembered words influence memory. However, it was previously unclear whether the forgetting of information is also influenced by these characteristics. In six experiments, we used an item-method directed forgetting task where we presented participants with to-be-remembered and to-be-forgotten words varying in font size (large or small), animacy (animate or inanimate), emotionality (negative or neutral), concreteness (high or low), frequency (high or low), and word length (long or short). Results revealed that animacy, emotionality, concreteness, frequency, and word length (but not font size) influenced both remembering and forgetting. Together, the present findings indicate that the characteristics of presented words can influence remembering as well as directed forgetting, providing further evidence that the remembering and forgetting processes are governed by similar properties.

Instructions to shift eyes do not increase item-method directed forgetting

Successful forgetting of recently-studied information has been shown to be positively correlated with eye movements [Lee, Y. (2018). Withdrawal of spatial overt attention following intentional forgetting: Evidence from eye movements. Memory (Hove, England), 26(4), 503-513. https://doi.org/10.1080/09658211.2017.1378360]. We tested whether eye movements caused forgetting by manipulating instructions to move eyes following forget and remember cues in item-method directed forgetting. In Experiment 1, participants were instructed to move eyes to the periphery after TBF trials or to focus on the centre where the TBF word and cue had been presented. In Experiment 2, we manipulated eye movement instructions within participants such that on half of the TBR and TBF trials participants shifted their eyes to the periphery, and on the other half of the trials, participants focused on the centre of the screen. Experiment 3 replicated Experiment 2 with an added probe task which ensured participants were moving their eyes as instructed. Results overall showed eye movements did not increase directed forgetting. Instructing participants to shift or focus eyes did not interact with the effectiveness of directed forgetting. Furthermore, metacognitive measures collected during study indicated that participants are sensitive to the significant effects of directed forgetting, but - like recall - judgments were not affected by eye movement instructions. From these findings, we concluded that eye movements do not promote intentional forgetting.

Item method directed forgetting occurs independently of borderline personality traits, even for borderline-salient items

Clinical populations sometimes demonstrate difficulties forgetting stimuli related to their trauma-related disorder, perhaps because their intense personal connection to these stimuli produce deficits in the inhibitory control abilities necessary for forgetting. The present work examined this possibility for people who have high levels of traits implicated in borderline personality disorder (BPD). In two well-powered studies, we found no evidence for deficits in forgetting specific to BPD traits, even for people with clinically significant levels of the traits, contrary to previous studies. The present experiments updated the designs from earlier experiments to employ the most contemporary methods to examine directed forgetting recommended by recent reviews. With these improved methods, Study 1 found that participants showed significant directed forgetting for BPD-related words independent of their level of BPD traits, perhaps because the BPD-related words were so strongly associated with one another. Study 2 found that when we removed the strong relatedness between the stimuli, forgetting of BPD-relevant words was significant and did not interact with BPD symptomology. We concluded that in contrast to people with PTSD who show specific inhibitory deficits for trauma-related works, people with BPD show normal, intact inhibitory control even for words that they should find threatening.

Failing to forget? Evidence for both impaired and preserved working memory control in older adults

Voluntary forgetting is accomplished via top-down control over memory contents. Age-related declines in cognitive control may compromise voluntary forgetting. Using a working-memory variant of a directed forgetting task, we examined age differences in forgetting efficacy by analyzing direct measures of memory accuracy and two indirect measures of retention: proactive interference and semantic distortions. The directed forgetting effect in long-term memory was virtually absent in older adults. Further, compared to young adults, older adults recognized fewer to-be-remembered and more to-be-forgotten items in working memory. However, indirect measures of forgetting efficacy suggest some spared ability to control working memory contents in older adults: Both young and older adult participants exhibited reduced proactive interference for to-be-forgotten words (Experiment 1) and reduced semantic errors to to-be-forgotten list associates (Experiment 2) in working memory. Indirect memory measures of forgetting efficacy can provide a fuller understanding of spared and impaired control processes in older adults.

Oscillatory Correlates of Intentional Forgetting: The Role of Theta and Alpha Power in Item-Method Directed Forgetting

Results from item-method directed forgetting suggest that individuals are able to intentionally forget processed information. Most research suggests that either selective rehearsal of to-be-remembered or inhibitory control of to-be-forgotten information is accountable for the effects of intentional forgetting. Some research, however, hypothesized that the time to process information mediates the underlying mechanism. To test this hypothesis, the current study investigated associations between oscillatory power in theta (3–7.5 Hz) and alpha frequencies (8–13 Hz) and intentional forgetting in human participants and explored whether or not these mechanisms depended on processing time. Previously, theta power was shown to be associated with the creation of episodic memory traces and alpha power with inhibition. We therefore expected to find associations between these neural signatures and behavioral effects. Consistent with our hypotheses, we revealed increased theta power for to-be-remembered and increased alpha power for to-be-forgotten information and that the effects of activity in both frequency bands were influenced by the time individuals were given for processing the memory cue. These results suggest that not one but two mechanisms, rehearsal and inhibitory control, are accountable for item-method directed forgetting, both with different temporal profiles.

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.

Separation of item and context in item-method directed forgetting

Contextual information plays a critical role in directed forgetting (DF) of lists of items, whereas DF of individual items has been primarily associated with item-level processing. This study was designed to investigate whether context processing also contributes to the forgetting of individual items. Participants first viewed a series of words, with task-irrelevant scene images (used as "context tags") interspersed between them. Later, these words reappeared without the scenes and were followed by an instruction to remember or forget that word. Multivariate pattern analyses of fMRI data revealed that the reactivation of context information associated with the studied words (i.e., scene-related activity) was greater whereas the item-related information diminished after a forget instruction compared to a remember instruction. Critically, we found the magnitude of the separation between item information and context information predicted successful forgetting. These results suggest that the unbinding of an item from its context may support the intention to forget, and more generally they establish that contextual processing indeed contributes to item-method DF.

Intention matters more than attention: Item-method directed forgetting of items at attended and unattended locations

This study embedded attentional cues in the study phase of an item-method directed forgetting task. We used an unpredictive onset cue (Experiment 1), a predictive onset cue (Experiment 2), or a predictive central cue (Experiments 3-6) to direct attention to the left or right. In Experiments 1-5, this was followed by a pink or blue study word that required a speeded colour discrimination; in Experiment 6, it was followed by a pink or blue word or nonword that required a lexical decision. Each study word was followed by an instruction to Remember or Forget. A yes-no recognition test confirmed better recognition of to-be-remembered words than to-be-forgotten words; a cueing effect confirmed the effectiveness of predictive cues in allocating attentional resources. There was, however, no evidence that the directed forgetting effect differed for attended and unattended words: Encoding depends more on the memory intention formed after a study word has disappeared than on the availability of processing resources when that word first appears.

Emotional memories are (usually) harder to forget: A meta-analysis of the item-method directed forgetting literature

The current meta-analysis explored whether emotional memories are less susceptible to item-method directed forgetting than neutral memories. Basic analyses revealed superior memory for remember (R) than forget (F) items in both the neutral, M = 19.6%, CI_95% [16.1, 23.1], and the emotional, M = 15.1%, CI_95% [12.4, 17.7], conditions. Directed forgetting in either valence condition was larger for (a) words than for other stimuli; (b) recall than recognition tests; (c) studies that used recall prior to recognition testing; (d) shorter lists; and (e) studies that included buffer items. Direct comparison of the magnitude of the directed forgetting effect across neutral and emotional conditions within studies revealed relatively diminished directed forgetting of emotional items compared to neutral items, with an average difference of 4.2%, CI_95% [2.0, 6.4]. However, the nature of this finding varied broadly across studies, meaning that whether - and to what degree - emotional memories are more resilient than neutral memories likely depends on the methodological features of the study in question. Moderator analyses revealed larger differences (a) in studies for which the emotional items were more arousing than the neutral items, and (b) when buffer items were included. Together, these findings suggest that emotional memories are often more resilient to intentional forgetting than neutral memories, although further research is necessary to characterize the circumstances under which these differences emerge.

Forgetting under difficult conditions: Item-method directed forgetting under perceptual processing constraints

Intentional forgetting of unwanted items is effortful, yet directed forgetting seems to improve when a secondary task is performed. According to the cognitive load hypothesis of directed forgetting, allocating attentional resources to another task improves forgetting by restricting unwanted encoding of to-be-forgotten (TBF) items. Alternatively, it might be that anything that makes studying more difficult will encourage greater effort to perform the task well and therefore lead to improved intentional forgetting. To assess these proposals we imposed data-processing limitations on study words in an item-method directed forgetting paradigm. Across six experiments, the perceptual quality of study words was manipulated by varying: (1) the duration of study word presentation (Experiments 1-4); (2) the contrast of the displayed word against its visual background (Experiment 5); or (3) the amount of visual background noise on which the word was presented (Experiment 6). In Experiments 4-6, a lexical decision task corroborated the difficulty of study word processing. Despite evidence that relatively low visual contrast and relatively high visual background noise, in particular, create challenging conditions, we found no evidence that perceptual quality impacts the magnitude of the directed forgetting effect. This work suggests that data limitations have no discernible effect on forgetting and corroborate that only attentional resource limitations improve directed forgetting.

ERP and behavioural measures of cognitive effort associated to forget negative and neutral words

The cognitive effort associated with remembering (R) vs forgetting (F) neutral and negative words was analyzed through a visual detection task integrated in an item-method directed forgetting task. Thirty-three younger adults participated in the experiment while their electrophysiological activity was registered in the study phase. The results shown: (1) negative words evoked more positive ERPs than neutral words on frontal regions, suggesting a preferential processing of negative words. (2) F-cues evoked more positive ERPs than R-cues did for neutral rather than negative words between 500 and 900 ms. This effect could reflect the difficulty in implementing inhibitory mechanisms on negative words. (3) At visual detection task, RTs for post-F probes were longer than for post-R probes. In 350-550 ms time window, ERPs were more positive for post-F probes than post-R probes in over right frontal regions and left medial parietal regions. Additionally, larger P2 were evoked by post-F negative probes than by post-R negative and post-F neutral ones. (4) In recognition test, participants recognized more negative TBF words than neutral ones. The ERP and behavioral results indicate that forgetting is more difficult than remembering, especially when words have a negative content, which implies a greater recruitment of parietal and frontal regions.

What can directed forgetting tell us about clinical populations?

This paper reviews and critically assesses the implications of directed forgetting (DF) research on clinical populations. We begin by reviewing the typical methods and results of the item method and list method directed forgetting procedures and provide best practice recommendations for future studies using clinical populations. Next, we note that DF was often interpreted as being due to inhibition, and when clinical populations showed impaired directed forgetting, it was treated as evidence in inhibitory control difficulties. However, inhibition may not be the cause of DF effects, based on current understanding of these cognitive tasks. We instead suggest that item method DF is tied to attentional control, which might include inhibitory mechanisms (or might not). In contrast, list method DF is tied to two forms of memory control: control of mental context (indicated by effective forgetting of List 1), and changes in the strategies used to remember (indicated by better learning of List 2). We review the current state of the clinical DF literature, assess its strength based on our best practice recommendations, and call for more research when warranted.

Parameters of Memory Reconsolidation: Learning Mode Influences Likelihood of Memory Modification

When previously consolidated hippocampally dependent memory traces are reactivated they enter a vulnerable state in which they can be altered with new information, after which they must be re-consolidated in order to restabilize the trace. The existing body of literature on episodic reconsolidation largely focuses on the when and how of successful memory reactivation. What remains poorly understood is how the nature of newly presented information affects the likelihood of a vulnerable episodic memory being altered. We used our episodic memory reconsolidation paradigm to investigate if the intention to encode impacts what subsequently becomes attributed to an older, reactivated memory. Participants learned two lists of objects separated by 48 h. We integrated a modified item-list directed-forgetting paradigm into the encoding of the second object list by cueing participants to learn some of the objects intentionally (intentional learning), while other objects were presented without a cue (incidental learning). Under conditions of memory reactivation, subjects showed equal rates of memory modification for intentionally- and incidentally-learned objects. However, in the absence of reactivation we observed high misattribution rates of incidentally-learned objects. We consider two interpretations of these data, with contrasting implications for understanding the conditions that influence memory malleability, and suggest further work that should help decide between them.

Active Forgetting: Adaptation of Memory by Prefrontal Control

Over the past century, psychologists have discussed whether forgetting might arise from active mechanisms that promote memory loss to achieve various functions, such as minimizing errors, facilitating learning, or regulating one's emotional state. The past decade has witnessed a great expansion in knowledge about the brain mechanisms underlying active forgetting in its varying forms. A core discovery concerns the role of the prefrontal cortex in exerting top-down control over mnemonic activity in the hippocampus and other brain structures, often via inhibitory control. New findings reveal that such processes not only induce forgetting of specific memories but also can suppress the operation of mnemonic processes more broadly, triggering windows of anterograde and retrograde amnesia in healthy people. Recent work extends active forgetting to nonhuman animals, presaging the development of a multilevel mechanistic account that spans the cognitive, systems, network, and even cellular levels. This work reveals how organisms adapt their memories to their cognitive and emotional goals and has implications for understanding vulnerability to psychiatric disorders.

In support of selective rehearsal: Double-item presentation in item-method directed forgetting

Despite the substantial evidence highlighting the role of selective rehearsal in item-method directed forgetting, recent work has suggested that forgetting may occur as a function of an active inhibitory mechanism that is more effortful than elaborative rehearsal processes. In the present work, we test this hypothesis by implementing a double-item presentation within the item-method directed forgetting paradigm. Participants studied two unrelated items at a time. Some words were followed by the same cue, and participants were instructed to remember or forget both items (pure condition). On other trials, participants were to remember one but forget the other word (mixed condition). Selective rehearsal and inhibition accounts make distinct predictions regarding memory performance in the double-item presentation. In Experiment 1, we compared recognition performance in the pure and mixed conditions, while in Experiment 2, we included a neutral baseline condition to further distinguish between the selective rehearsal and inhibition accounts. Contrary to the inhibition account but consistent with selective rehearsal, we found for both remember and forget items that recognition was greater in the mixed than in the pure condition. Recognition for forget items also did not differ from neutral items. We conclude that selective rehearsal, not inhibition, is responsible for item-method directed forgetting.

High-Intensity Acute Exercise and Directed Forgetting on Memory Function

Background and Objectives: Despite accumulating research demonstrating that acute exercise may enhance memory function, very little research has evaluated whether acute exercise can effectuate intentional directed forgetting (DF), an adaptative strategy to facilitate subsequent memory performance. Materials and Methods: A three-arm parallel-group randomized controlled intervention was employed. Participants were randomized into one of three groups, including: (1) exercise plus DF (Ex + DF), (2) DF (directed forgetting) only (DF) and (3) R (remember) only (R). The acute bout of exercise included 15 min of high-intensity treadmill exercise. The memory assessment involved the presentation of two-word lists. After encoding the first word list, participants were either instructed to forget all of those words (DF) or to remember them. Following this, participants encoded the second word list. Results: We observed a statistically significant main effect for list F(1, 57) = 12.27, p < 0.001, η²_p = 0.18, but no main effect for group F(2, 57) = 1.32, p = 0.27, η²_p = 0.04, or list by group interaction, F(2, 57) = 2.89, p = 0.06, η²_p = 0.09. Conclusions: This study demonstrates a directed forgetting effect in that cueing an individual to forget a previously encoded list of items facilitates memory performance on a subsequent list of items. However, we failed to demonstrate any beneficial effect of acute exercise in facilitating directed forgetting. These findings are discussed in the context of directed forgetting theories, particularly the attention inhibition mechanism, as well as the timing of the acute bout of exercise.

The role of forgetting cues in directed forgetting: Ceasing maintenance rehearsal

The effect of forgetting cues on maintenance rehearsal in item-method directed forgetting (DF) paradigm was explored from behavioral and electrophysiological evidence. In Experiment 1, maintenance rehearsal was induced by a maintenance cue. Specifically, after the studied word, a maintenance (M) cue was presented before the presentation of a remembering/forgetting cue. When an M cue appeared, participants were required to wait for the following remembering (M-R) or forgetting (M-F) cue to determine whether the word needs to be remembered or not, and words were kept in short-term memory with maintenance rehearsal until the presentation of M-R/M-F cues. Four conditions were utilized: maintain-remembering (M-R), maintain-forgetting (M-F), maintenance (M), and forgetting (F). The results showed that, 1) superior recognition was found for the M-R relative to the M-F words, revealing a typical DF effect; 2) No recognition difference was found between M and M-F words, indicating that M-F cues showed little effect in promoting forgetting; 3) Inferior recognition was found for F than M words, indicating that the maintenance rehearsal might cease or be reduced by the presentation of F cues. In Experiment 2, event related potentials time-locked to cue (M-R, M-F, M, and F cues) onset during study phase. An enhanced fronto-central P3a component was evoked for F relative to M cues, indicating a more intensive attention orienting or attentional inhibition process triggered by F cues. These results demonstrated that forgetting cues might trigger an inhibition process to terminate the maintenance rehearsal process.

Remember to blink: Reduced attentional blink following instructions to forget

This study used rapid serial visual presentation (RSVP) to determine whether, in an item-method directed forgetting task, study word processing ends earlier for forget words than for remember words. The critical manipulation required participants to monitor an RSVP stream of black nonsense strings in which a single blue word was embedded. The next item to follow the word was a string of red fs that instructed the participant to forget the word or green rs that instructed the participant to remember the word. After the memory instruction, a probe string of black xs or os appeared at postinstruction positions 1-8. Accuracy in reporting the identity of the probe string revealed an attenuated attentional blink following instructions to forget. A yes-no recognition task that followed the study trials confirmed a directed forgetting effect, with better recognition of remember words than forget words. Considered in the context of control conditions that required participants to commit either all or none of the study words to memory, the pattern of probe identification accuracy following the directed forgetting task argues that an intention to forget releases limited-capacity attentional resources sooner than an instruction to remember-despite participants needing to maintain an ongoing rehearsal set in both cases.

Decomposing item-method directed forgetting of emotional pictures: Equivalent costs and no benefits

Using an item-method directed forgetting task, we presented negative, neutral, and positive photographic pictures, one at a time, each followed by an instruction to remember or forget. We determined that the directed forgetting effect, defined as better subsequent recognition of to-be-remembered (TBR) items than to-be-forgotten (TBF) items, was equivalent across negative, neutral, and positive pictures. To disentangle the underlying costs (i.e., decrease in memory for TBF items) and benefits (i.e., increase in memory for TBR items), we compared recognition memory performance in the directed forgetting task to that of a novel within-subjects remember-all control condition (Experiment 1) and to a between-subjects remember-all control group (Experiment 2). We observed costs without benefits across all three emotions-negative, neutral, and positive-in both experiments. These results demonstrate that equivalent directed forgetting effects for emotional stimuli are not attributable to different underlying component processes. Instead, our results suggest that selection for encoding is accomplished in similar ways, regardless of emotional content.

Too hard to forget? ERPs to remember, forget, and uninformative cues in the encoding phase of item-method directed forgetting

In item-method directed forgetting, worse memory performance occurs for to-be-forgotten (TBF) than for to-be-remembered (TBR) items. However, recently TBF items have been found to be recognized more accurately than uninformative (UI) items not associated with any specific task. Here, we compare ERPs elicited by cues signaling the remember or the forget instruction with those elicited by uninformative cues. Participants were presented with a series of complex pictures, each followed by a symbolic TBR, TBF, or UI cue. On a yes-no recognition test, accuracy was higher for TBR than for both TBF and UI items. However, TBF items were recognized more accurately than UI items. ERPs elicited by the TBR cue were larger than ERPs elicited by both TBF and UI cues at the frontal P2, the late frontal negativity, and the late parietal positivity complex. This is consistent with more attention capture, selective rehearsal, and long-term memory encoding of TBR. In contrast, both TBF and UI cues induced a larger frontal N2 than TBR cues. Critically, TBF elicited a larger late right-frontal positivity than both UI and TBR cues and a larger late parietal positivity than UI cues. Moreover, the late right-frontal positivity was correlated with better recognition performance. It may therefore reflect processing orientation rather than inhibition per se. Results suggest that, when compared to UI cues, both TBR and TBF cues are processed actively. Distinct processing is seen at right frontal and centroparietal positive ERPs that may mediate better subsequent recognition of TBF than of UI items.

A grand memory for forgetting: Directed forgetting across contextual changes

Using an item-method directed forgetting task, we presented homographic homophonic nouns embedded in sentences. At study, each sentence was followed by an instruction to remember or forget the embedded word. On a subsequent yes-no recognition test, each word was again embedded within a sentence. In Experiments 1, 2, and 4 we varied the embedding sentence at test so that it was identical to that at study, changed but retained the meaning of the studied word, or changed to alter the meaning of the studied word. Repeated context - whether the sentence and/or the word meaning - proved to be as useful a retrieval cue for TBF items as for TBR items. In Experiment 3, we demonstrated that physical repetition was insufficient to produce context effects for either TBR or TBF items. And, in Experiment 4, we determined that participants were equally accurate in reporting context repetition/change following the correct recognition of TBR and TBF items. When considered in light of the existing literature, our results suggest that when context can be dissociated from the study item, it is encoded in "one shot" and not vulnerable to subsequent efforts to limit unwanted encoding.

Item-method directed forgetting: Effects at retrieval?

In an item-method directed forgetting paradigm, words are presented one at a time, each followed by an instruction to Remember or Forget; a directed forgetting effect is measured as better subsequent memory for Remember words than Forget words. The dominant view is that the directed forgetting effect arises during encoding due to selective rehearsal of Remember over Forget items. In three experiments we attempted to falsify a strong view that directed forgetting effects in recognition are due only to encoding mechanisms when an item method is used. Across 3 experiments we tested for retrieval-based processes by colour-coding the recognition test items. Black colour provided no information; green colour cued a potential Remember item; and, red colour cued a potential Forget item. Recognition cues were mixed within-blocks in Experiment 1 and between-blocks in Experiments 2 and 3; Experiment 3 added explicit feedback on the accuracy of the recognition decision. Although overall recognition improved with cuing when explicit test performance feedback was added in Experiment 3, in no case was the magnitude of the directed forgetting effect influenced by recognition cueing. Our results argue against a role for retrieval-based strategies that limit recognition of Forget items at test and posit a role for encoding intentions only.

Item-method directed forgetting and working memory capacity: A hierarchical multinomial modeling approach

Intentional forgetting of information that has recently been encoded is regarded an active and adaptive process and is widely studied using the item-method or the list-method directed forgetting (DF) paradigm. In the present research, we tested whether inter-individual differences in working-memory capacity (WMC), that have been identified as a relevant predictor of DF within the list method, are also related to stronger DF effects within the item method. Furthermore, we investigated relationships between WMC and item-method DF at different processing stages by applying the multinomial storage–retrieval model hierarchically to our data. Results showed that individuals with high WMC are better able to store to-be-remembered information than individuals with low WMC, whereas WMC was not related to retrieval of to-be-remembered information or to either storage or retrieval of to-be-forgotten information. Implications for theoretical accounts of item-method DF are discussed.

Forget Me if You Can: Attentional capture by to-Be-remembered and to-Be-forgotten visual stimuli

Previous studies on directed forgetting in visual working memory (VWM) have shown that, if people are cued to remember only a subset of the items currently held in VWM, they will completely forget the uncued, no longer relevant items. While this finding is indicative of selective remembering, it remains unclear whether directed forgetting can also occur in the absence of any concurrent to-be-remembered information. In the current study, we addressed this matter by asking participants to memorize a single object that could be followed by a cue to forget or remember this object. Following the cue, we assessed the object’s activation in VWM by determining whether a matching distractor would capture attention in a visual search task. The results showed that, compared to a cue to remember, a cue to forget led to a reduced likelihood of attentional capture by a matching distractor. In addition, we found that capture effects by to-be-remembered and to-be-forgotten distractors remained stable as the interval between the onset of the cue and the search task increased from 700 ms to 3900 ms. We conclude that, in the absence of any to-be-remembered objects, an instruction to forget an object held in WM leads to a rapid but incomplete deactivation of the representation of that object, thus allowing it to continue to produce a weak biasing effect on attentional selection for several seconds after the instruction to forget.

No evidence for age-related differences in item-method directed forgetting of emotional words

Research indicates that people can intentionally forget, but it is less clear how ageing and emotion interact with this ability. The present research investigated item-method directed forgetting of negative, neutral, and positive words in young (20-35 years), young-old (60-74 years), and old-old (75-89 years) adults. Although old-old adults showed overall reduced memory compared to young and young-old adults, all three age groups showed intentional forgetting. Moreover, intentional forgetting was not affected by the valence of the word in any of the three age groups. These findings suggest that younger and older adults can intentionally forget information that is neutral or emotional in nature. The present study's results extend previous research by showing that this ability is preserved in very old age.

What Is the Effect of Basic Emotions on Directed Forgetting? Investigating the Role of Basic Emotions in Memory

Studies presenting memory-facilitating effect of emotions typically focused on affective dimensions of arousal and valence. Little is known, however, about the extent to which stimulus-driven basic emotions could have distinct effects on memory. In the present paper we sought to examine the modulatory effect of disgust, fear, and sadness on intentional remembering and forgetting using widely used item-method directed forgetting (DF) paradigm. Eighteen women underwent fMRI scanning during encoding phase in which they were asked either to remember (R) or to forget (F) pictures. In the test phase all previously used stimuli were re-presented together with the same number of new pictures and participants had to categorize them as old or new, irrespective of the F/R instruction. On the behavioral level we found a typical DF effect, i.e., higher recognition rates for to-be-remembered (TBR) items than to-be-forgotten (TBF) ones for both neutral and emotional categories. Emotional stimuli had higher recognition rate than neutral ones, while among emotional those eliciting disgust produced highest recognition, but at the same time induced more false alarms. Therefore, when false alarm corrected recognition was examined the DF effect was equally strong irrespective of emotion. Additionally, even though subjects rated disgusting pictures as more arousing and negative than other picture categories, logistic regression on the item level showed that the effect of disgust on recognition memory was stronger than the effect of arousal or valence. On the neural level, ROI analyses (with valence and arousal covariates) revealed that correctly recognized disgusting stimuli evoked the highest activity in the left amygdala compared to all other categories. This structure was also more activated for remembered vs. forgotten stimuli, but only in case of disgust or fear eliciting pictures. Our findings, despite several limitations, suggest that disgust have a special salience in memory relative to other negative emotions, which cannot be put down to differences in arousal or valence. The current results thereby support the suggestion that a purely dimensional model of emotional influences on cognition might not be adequate to account for observed effects.

The representational consequences of intentional forgetting: Impairments to both the probability and fidelity of long-term memory

We investigated whether intentional forgetting impacts only the likelihood of later retrieval from long-term memory or whether it also impacts the fidelity of those representations that are successfully retrieved. We accomplished this by combining an item-method directed forgetting task with a testing procedure and modeling approach inspired by the delayed-estimation paradigm used in the study of visual short-term memory (STM). Abstract or concrete colored images were each followed by a remember (R) or forget (F) instruction and sometimes by a visual probe requiring a speeded detection response (E1-E3). Memory was tested using an old-new (E1-E2) or remember-know-no (E3) recognition task followed by a continuous color judgment task (E2-E3); a final experiment included only the color judgment task (E4). Replicating the existing literature, more "old" or "remember" responses were made to R than F items and RTs to postinstruction visual probes were longer following F than R instructions. Color judgments were more accurate for successfully recognized or recollected R than F items (E2-E3); a mixture model confirmed a decrease to both the probability of retrieving the F items as well as the fidelity of the representation of those F items that were retrieved (E4). We conclude that intentional forgetting is an effortful process that not only reduces the likelihood of successfully encoding an item for later retrieval, but also produces an impoverished memory trace even when those items are retrieved; these findings draw a parallel between the control of memory representations within working and long-term memory.

'Forget me (not)?' - Remembering Forget-Items Versus Un-Cued Items in Directed Forgetting

Humans need to be able to selectively control their memories. This capability is often investigated in directed forgetting (DF) paradigms. In item-method DF, individual items are presented and each is followed by either a forget- or remember-instruction. On a surprise test of all items, memory is then worse for to-be-forgotten items (TBF) compared to to-be-remembered items (TBR). This is thought to result mainly from selective rehearsal of TBR, although inhibitory mechanisms also appear to be recruited by this paradigm. Here, we investigate whether the mnemonic consequences of a forget instruction differ from the ones of incidental encoding, where items are presented without a specific memory instruction. Four experiments were conducted where un-cued items (UI) were interspersed and recognition performance was compared between TBR, TBF, and UI stimuli. Accuracy was encouraged via a performance-dependent monetary bonus. Experiments varied the number of items and their presentation speed and used either letter-cues or symbolic cues. Across all experiments, including perceptually fully counterbalanced variants, memory accuracy for TBF was reduced compared to TBR, but better than for UI. Moreover, participants made consistently fewer false alarms and used a very conservative response criterion when responding to TBF stimuli. Thus, the F-cue results in active processing and reduces false alarm rate, but this does not impair recognition memory beyond an un-cued baseline condition, where only incidental encoding occurs. Theoretical implications of these findings are discussed.

Memory instruction interacts with both visual and motoric inhibition of return

In the item-method directed forgetting paradigm, the magnitude of inhibition of return (IOR) is larger after an instruction to forget (F) than after an instruction to remember (R). In the present experiments, we further investigated this increased magnitude of IOR after F than after R memory instructions, to determine whether this F > R IOR pattern occurs only for the motoric form of IOR, as predicted, or also for the visual form. In three experiments, words were presented in one of two peripheral locations, followed by either an F or an R memory instruction. Then, a target appeared either at the same location as the previous word or at the other location. In Experiment 1, participants maintained fixation throughout the trial until the target appeared, at which point they made a saccade to the target. In Experiment 2, they maintained fixation throughout the entire trial and made a manual localization response to the target. The F > R IOR difference in reaction times occurred for both the saccadic and manual responses, suggesting that memory instructions modify both motoric and visual forms of IOR. In Experiment 3, participants made a perceptual discrimination response to report the identity of a target while the eyes remained fixed. The F > R IOR difference also occurred for these manual discrimination responses, increasing our confidence that memory instructions modify the visual form of IOR. We relate our findings to postulated differences in attentional withdrawal following F and R instructions and consider the implications of the findings for successful forgetting.

Inhibition-induced forgetting: when more control leads to less memory

The ability to inhibit prepotent responses is a core executive function, but the relation of response inhibition to other cognitive operations is poorly understood. In the study reported here, we examined inhibitory control through the lens of incidental memory. Participants categorized face stimuli by gender in a go/no-go task (Experiments 1 and 2) or a stop-signal task (Experiment 3) and, after a short delay, performed a surprise recognition memory task for those faces. Memory was impaired for stimuli presented during no-go and stop trials compared with those presented during go trials. Experiment 4 showed that this inhibition-induced forgetting was not attributable to event congruency. In Experiment 5, we combined a go/no-go task with a dot-probe test and found that probe detection during no-go trials was inferior to that on go trials. This result supports the hypothesis that inhibition-induced forgetting occurs when response inhibition shunts attentional resources from perceptual stimulus encoding to action control.

Neural mechanisms of motivated forgetting

•

Motivated forgetting of unwanted memories shapes what we retain of our personal past.

•

Motivated forgetting is achieved in part by inhibitory control over encoding or retrieval.

•

Prefrontal cortex reduces hippocampal and cortical activity to suppress memories.

•

Electrophysiological activity during motivated forgetting implicates active inhibition.

•

A neurobiological model of memory control can inform disordered control over memory.

Not all memories are equally welcome in awareness. People limit the time they spend thinking about unpleasant experiences, a process that begins during encoding, but that continues when cues later remind someone of the memory. Here, we review the emerging behavioural and neuroimaging evidence that suppressing awareness of an unwelcome memory, at encoding or retrieval, is achieved by inhibitory control processes mediated by the lateral prefrontal cortex. These mechanisms interact with neural structures that represent experiences in memory, disrupting traces that support retention. Thus, mechanisms engaged to regulate momentary awareness introduce lasting biases in which experiences remain accessible. We argue that theories of forgetting that neglect the motivated control of awareness omit a powerful force shaping the retention of our past.

Event-method directed forgetting: forgetting a video segment is more effortful than remembering it

Videos were presented depicting events such as baking cookies or cleaning a fish tank. Periodically, the video paused and an instruction to Remember (R) or Forget (F) the preceding video segment was presented; the video then resumed. Participants later responded more accurately to cued-recall questions (E1) and to true/false statements (E2-5) regarding R segments than F segments. This difference was larger for specific information (the woman added 3 cups of flour) than for general information (the woman added flour). Participants were also slower to detect visual probes presented following F instructions compared to those presented following R instructions. These findings suggest that intentional forgetting is an effortful process that can be performed even on segments of otherwise continuous events and that the result is a relatively impoverished representation of the unwanted information in memory.