Abstract: Preface.- Introduction.- The Cognitive Neuroscience of True and False Memories.- Searching for Repressed Memory.- Motivated Forgetting and Misremembering.- Cognitive Underpinnings of Recovered Memories of Childhood Abuse.- A Theoretical Framework for Understanding Recovered Memory Experiences.

Abstract: Individuals are sometimes exposed to information that may endanger their well-being. In such cases, forgetting or misremembering may be adaptive. Childhood abuse perpetrated by a caregiver is an example. Betrayal trauma theory (BTT) proposes that the way in which events are processed and remembered will be related to the degree to which a negative event represents a betrayal by a trusted, needed other. Full awareness of such abuse may only increase the victim’s risk by motivating withdrawal or confrontation with the perpetrator, thus risking a relationship vital to the victim’s survival. In such situations, minimizing awareness of the betrayal trauma may be adaptive. BTT has implications for the larger memory and trauma field, particularly with regard to forgetting and misremembering events. This chapter reviews conceptual and empirical issues central to the literature on memory for trauma and BTT as well as identifies future research directions derived from BTT.

Abstract: Neural synchronization between distant cell assemblies is crucial for the formation of new memories. To date, however, it remains unclear whether higher-order brain regions can adaptively regulate neural synchrony to control memory processing in humans. We explored this question in two experiments using a voluntary forgetting task. In the first experiment, we simultaneously recorded electroencephalography along with fMRI. The results show that a reduction in neural synchrony goes hand-in-hand with a BOLD signal increase in the left dorsolateral prefrontal cortex (dlPFC) when participants are cued to forget previously studied information. In the second experiment, we directly stimulated the left dlPFC with repetitive transcranial magnetic stimulation during the same task, and show that such stimulation specifically boosts the behavioral forgetting effect and induces a reduction in neural synchrony. These results suggest that prefrontally driven downregulation of long-range neural synchronization mediates goal-directed forgetting of long-term memories.

Abstract: Research from the past decades has shown that retrieval of a speciffic memory (e.g., retrieving part of a previous vacation) typically attenuates retrieval of other memories (e.g., memories for other details of the event), causing retrieval-induced forgetting. More recently, however, it has been shown that retrieval can both attenuate and aid recall of other memories (K.-H. T. Bauml & A. Samenieh, 2010). To identify the circumstances under which retrieval aids recall, we examined retrieval dynamics in listwise directed forgetting, context-dependent forgetting, proactive interference, and in the absence of any induced memory impairment. We found benefificial effffects of selective retrieval in listwise directed forgetting and context- depedent forgetting, but detrimental effects in all the other conditions. Because context-dependent forgetting and listwise directed forgetting arguably reflect impaired context access, the results suggest that memory retrieval aids recall of memories that are subject to impaired context access, but attenuates recall in the absence of such circumstances. The findings are consistent with a two-factor account of memory retrieval and suggest the existence of two faces of memory retrieval.

Abstract: The directed forgetting paradigm is frequently used to determine the ability to voluntarily suppress information. However, little is known about brain areas associated with information to forget. The present study used functional magnetic resonance imaging to determine brain activity during the encoding and retrieval phases of an item-method directed forgetting recognition task with neutral verbal material in order to apprehend all processing stages that information to forget and to remember undergoes. We hypothesized that regions supporting few selective processes, namely recollection and familiarity memory processes, working memory, inhibitory and selection processes should be differentially activated during the processing of to-be-remembered and to-be-forgotten items. Successful encoding and retrieval of items to remember engaged the entorhinal cortex, the hippocampus, the anterior medial prefrontal cortex, the left inferior parietal cortex, the posterior cingulate cortex and the precuneus; this set of regions is well known to support deep and associative encoding and retrieval processes in episodic memory. For items to forget, encoding was associated with higher activation in the right middle frontal and posterior parietal cortex, regions known to intervene in attentional control. Items to forget but nevertheless correctly recognized at retrieval yielded activation in the dorsomedial thalamus, associated with familiarity-based memory processes and in the posterior intraparietal sulcus and the anterior cingulate cortex, involved in attentional processes.

Abstract: Across 3 experiments we examined the interplay of part-list cuing and forgetting, employing 3 different methods to induce episodic forgetting { list-method directed forgetting, context-dependent forgetting, and proactive interference. For each form of forgetting, participants were asked at test to recall the target items of a previously studied list, in the presence or the absence of the list's remaining items serving as retrieval cues. We found such part-list cuing to amplify the forgetting in proactive interference but to diminish the forgetting in list-method directed forgetting and context-dependent forgetting. These results show that the effects of part-list cuing on forgotten memories depend critically on the circumstances surrounding the forgetting. If the forgetting reflects impaired access to the original encoding context, as has been suggested in list-method directed forgetting and context-dependent forgetting (but not in proactive interference), part-list cues improve access to forgotten memories; if the forgetting does not reflect such a contextual effect, no such beneficial effects emerge and access to forgotten memories may even be impaired.

Abstract: This study examined the effect of the processing demands of to-be-remembered (TBR) words on item-method directed forgetting. Experiment 1 found that a standard memory group remembered fewer to-be-forgotten (TBF) words than a naming group, in which participants simply named the TBR words during the study phase, even though both groups were equally instructed to forget the TBF words. Experiment 2 manipulated the number of TBR words in the study list, keeping the number of TBF words constant, and found that TBF word forgetting was more difficult in the few TBR words condition than the more TBR words condition. The same pattern was found in the result of Experiment 3 when a cued recall test, instead of a free recall test, was used. In all the experiments, participants were asked to recall the TBF words before the TBR words. These findings are consistent with the cognitive load hypothesis that it is easier to forget when there are fewer cognitive resources available during encoding.

Abstract: Results. Results revealed DF, that is, reduced recognition for ' to-be-forgotten ' items in the non-PTSD but not in the PTSD group. Moreover, in the non-PTSD, but not in the PTSD group, false alarms were reduced for ' to-be- remembered ' items. Finally, DF was reduced in those participants who rated the pictures as more arousing, the PTSD group giving, on average, higher arousal ratings. Conclusions. Data indicate that DF is reduced in PTSD and that the reduction is related to stimulus arousal. Furthermore, individuals with PTSD are characterized by a more global encoding style than individuals without PTSD, reflected in a higher false alarm rate. In sum, traumatized individuals with (but not without) PTSD are impaired in their ability to selectively control episodic memory encoding. This impairment may contribute to clinical features of the disorder such as intrusions and flashbacks.

Abstract: The ability to remember an item can be blocked, or negatively primed, by exposure to related items. For example, ALLERGY is less likely to be generated given the word fragment A_L_ _GY if one is first exposed to ANALOGY. We examined whether this memory blocking effect is influenced by list-method directed forgetting. A total of 144 participants learned two lists of items, each consisting of words that were designed to negatively prime performance on a subsequent word fragment completion task. Participants who were told to forget List 1 before learning List 2 suffered significantly less memory blocking owing to the negative primes from List 1 than participants who were told to remember List 1. These results suggest that directed forgetting can modify the memory blocking effect by affecting the accessibility of information in memory.

Abstract: In list-method directed forgetting, people's ability to forget one of the sets of learned material is examined. Research shows that memory for to-be-forgotten items is impaired when assessed by a recall test and by recognition tests reliant on recollective processes. Retrieval inhibition and context-change mechanisms have been proposed to account for the directed forgetting effects and both of them account for the results obtained with recognition tests. However, the context change account makes a specific prediction that recollection is impaired by directed forgetting only if it makes use of contextual associations. In the present study, directed forgetting was examined with two types of recollection-based tasks making use of different types of associations, namely a list discrimination task utilising contextual associations and an associative recognition task utilising interitem associations. Consistent with the context change account, the costs of directed forgetting were observed in a list discrimination task and were not observed in an associative recognition task. The results indicate that impairment in recollection due to directed forgetting is not general and provide converging evidence to support the context-change account.

Abstract: Research in the past four decades has repeatedly shown that selective retrieval of some (non-target) memories can impair subsequent retrieval of other (target) information, a finding known as retrieval-induced forgetting. More recently, however, there is evidence that selective retrieval can both impair and enhance recall of related memories (K-H. T. Bauml & Samenieh, 2010). To identify possible experimental dissociations between the detrimental and the beneficial effects of memory retrieval, we examined retrieval dynamics in listwise directed forgetting, varying the delay between preceding non-target and subsequent target recall. When target recall immediately followed non-target recall, we replicated the prior work and found detrimental effects of memory retrieval on to-be-remembered items but beneficial effects on to-be-forgotten items. In contrast, when a delay was introduced between non-target and target recall, the detrimental effects were present but the beneficial effects were absent. The results demonstrate a first experimental dissociation between the two effects of memory retrieval. They are consistent with a recent two-factor account of the two faces of selective memory retrieval.

Abstract: Results of research investigating the link between anxiety sensitivity (AS) and memory biases toward threat have been inconsistent. There may be subgroups of high AS individuals who differ in their preferred mode of attending to threat-related information, thereby impacting memory. The impact of individual attention style on intentional forgetting of words varying in emotional valence was examined among individuals with varying levels of AS. By incorporating an inhibition of return (IOR) task (to yield a proxy of attentional allocation) within the study phase of the item-method directed forgetting paradigm, we categorized high, moderate, and low AS individuals according to their attention style in response to threat stimuli: ‘threat attenders’ (small IOR effect) and ‘threat avoiders’ (large IOR effect). Among high AS individuals only, ‘threat avoiders’ showed greater intentional forgetting of threat-related words than ‘threat attenders’. High AS ‘threat avoiders’ also had higher levels of anxiety-related psychopathology (AS and health anxiety) than high AS ‘threat attenders’.

Abstract: Background Intentional forgetting refers to the surprising phenomenon that we can forget previously successfully encoded memories if we are instructed to do so. Here, we show that participants cannot only intentionally forget episodic memories but they can also mirror the “forgetting performance” of an observed model. Methodology/Principal Findings In four experiments a participant observed a model who took part in a memory experiment. In Experiment 1 and 2 observers saw a movie about the experiment, whereas in Experiment 3 and 4 the observers and the models took part together in a real laboratory experiment. The observed memory experiment was a directed forgetting experiment where the models learned two lists of items and were instructed either to forget or to remember the first list. In Experiment 1 and 3 observers were instructed to simply observe the experiment (“simple observation” instruction). In Experiment 2 and 4, observers received instructions aimed to induce the same learning goal for the observers and the models (“observation with goal-sharing” instruction). A directed forgetting effect (the reliably lower recall of to-be-forgotten items) emerged only when models received the “observation with goal-sharing” instruction (P .1 in Experiment 1 and 3). Conclusion If people observe another person with the same intention to learn, and see that this person is instructed to forget previously studied information, then they will produce the same intentional forgetting effect as the person they observed. This seems to be a an important aspect of human learning: if we can understand the goal of an observed person and this is in line with our behavioural goals then our learning performance will mirror the learning performance of the model.

Abstract: The influence of self-reference and emotionally valent material on list-method directed forgetting was investigated. Participants studied lists 1 and 2, both of which consisted of positive, negative, and neutral trait adjectives. Each participant was randomly assigned to one of three experimental conditions: self-reference judgment, social desirability judgment, and control (no specific judgment). Half of the participants in each condition received the forget instruction telling them to forget list 1 and to remember list 2 (forget group). The other half received the remember instruction telling them to remember both lists 1 and 2 (remember group). All participants were then asked to recall all the list words, including those that they were instructed to forget. Results indicated that the directed forgetting effect disappeared in the self-reference judgment condition: in the forget group, list 1 recall was poorer than recall of list 2, and the Forget group participants recalled fewer list 1 words compared to the remember group participants. Neither the emotional valence nor self-reference of the material modulated the magnitude of this effect. It is concluded that self-reference may modify directed forgetting.

Abstract: Across six experiments, I examined the role of metacognitive control in item-method directed forgetting. In Experiment 1, participants studied loud and quiet items, which were subsequently cued as to-be-remembered (TBR) or to-be-forgotten (TBF). Typically, the volume of stimuli does not influence recall, although loud items are judged as more memorable than quiet items (Rhodes & Castel, 2009). In contrast, there was a unique recall advantage for loud TBR items when participants engaged in directed forgetting. Giving participants extra opportunities to engage rehearsal does not produce the selective advantage for loud items (Experiment 2), nor does emphasizing the importance of some items over others (Experiments 3 and 4). Experiment 5 manipulated the encoding fluency of the stimuli using a font type manipulation, which did not produce recall differences between the fluently and less fluently processed items despite the effect of font type on judgments of learning. Finally, Experiment 6 investigated participants' beliefs about what helps them disengage from TBF items and what helps them retain TBR items. Specifically, after TBF or TBR items, participants were told to select earlier studied line drawings that varied both in perceptual size (small vs. large size image) and conceptual size (drawing of a small vs. large object in real life). I propose two mechanisms to explain the results. According to the rehearsal strategy mechanism, people use beliefs about item memorability to selectively rehearse certain items as a way to forget other items. According to the salience mechanism, people are drawn to perceptually salient stimuli when performing directed forgetting.

Abstract: We investigated the role of emotion on item and source memory using the item method of directed forgetting (DF) paradigm. We predicted that emotion would produce source memory impairment because emotion would make it more difficult to distinguish between to-be-remembered (R items) and to-be-forgotten items (F items) by making memory strength of R and F items similar to each other. Participants were presented with negatively arousing, positively arousing, and neutral pictures. After each picture, they received an instruction to remember or forget the picture. At retrieval, participants were asked to recall both R and F items and indicate whether each item was an R or F item. Recall was higher for the negatively arousing than for the positively arousing or neutral pictures. Further, DF occurred for the positively arousing and neutral pictures, whereas DF was not significant for the negatively arousing pictures. More importantly, the negatively arousing pictures, particularly the ones with violent content, showed a higher tendency of producing misattribution errors than the other picture types, supporting the notion that negative emotion may produce source memory impairment, even though it is still not clear whether the impairment occurs at encoding or retrieval.

Abstract: After encoding, memory contents need to undergo a phase of stabilization in order to be remembered in the long-term. Such stabilization is referred to as memory consolidation, and is assumed to be observable in less time-dependent forgetting and less susceptibility to interference. Evidence for a role of sleep in the effective consolidation of memories has previously been provided. In addition, research on the so-called testing effect has also indicated a contribution of retrieval practice to long-term memory, as the active retrieval from memory has been shown to be able to boost retention. This thesis investigated effects of sleep and retrieval on memory consolidation. Effects of sleep-associated memory consolidation were examined by inducing interference in paired-associate learning and by applying list-method directed forgetting: Replicating previous work, sleep was found to be of preferential benefit for memories that are hard to access; thereby, sleep counteracted both incidental and intentional forms of forgetting. Applying the retrieval-practice paradigm, effects of retrieval-associated consolidation were observed: Retrieval was found to stabilize directly retrieved and related memories, thereby making them less susceptible to both time-dependent forgetting and retroactive interference. The data presented here indicate that both sleep and retrieval may be associated with memory consolidation. Possible differences and parallels between sleep-associated and retrieval-associated memory consolidation as well as implications of such a proposal are discussed.

Abstract: In list-method directed forgetting, people are cued to forget a previously studied item list and to learn a new list instead Such cuing typically leads to forgetting of the first list and to memory enhancement of the second, referred to as list 1 forgetting and list 2 enhancement In the present study, two experiments are reported that examined influences of items’ serial learning position in a list and the two lists’ output order on list-method directed forgetting The results show that list output order influences list 2 enhancement but not list 1 forgetting The enhancement was higher when list 2 was recalled first than when list 1 was recalled first and, in both cases, was higher for early list 2 items than for middle and late list 2 items In contrast, the forgetting was equally present for all list 1 items and did not depend on the two lists’ output order The findings suggest that two separate factors can contribute to list 2 enhancement: one (encoding) factor that is restricted to early list 2 items and does not depend on list output order, and another (retrieval) factor that pertains to all list 2 items and varies with the two lists’ output order A new two-mechanism account of directed forgetting is suggested that reconciles previous (encoding or retrieval) views on list 2 enhancement

Abstract: Remembering the past is a core feature of human beings, enabling them to maintain a sense of wholeness and identity and preparing them for the demands of the future. Forgetting operates in a dynamic neural connection with remembering, allowing the elimination of unnecessary or irrelevant information overload and decreasing interference. Stress and traumatic experiences could affect this connection, resulting in memory disturbances, such as functional amnesia. An overview of clinical, epidemiological, neuropsychological, and neurobiological aspects of functional amnesia is presented, by preponderantly resorting to own data from patients with functional amnesia. Patients were investigated medically, neuropsychologically, and neuroradiologically. A detailed report of a new case is included to illustrate the challenges posed by making an accurate differential diagnosis of functional amnesia, a condition that may encroach on the boundaries between psychiatry and neurology. Several mechanisms may play a role in "forgetting" in functional amnesia, such as retrieval impairments, consolidating defects, motivated forgetting, deficits in binding and reassembling details of the past, deficits in establishing a first person autonoetic connection with personal events, and loss of information. In a substantial number of patients, we observed a synchronization abnormality between a frontal lobe system, important for autonoetic consciousness, and a temporo-amygdalar system, important for evaluation and emotions, which provides empirical support for an underlying mechanism of dissociation (a failure of integration between cognition and emotion). This observation suggests a mnestic blockade in functional amnesia that is triggered by psychological or environmental stress and is underpinned by a stress hormone mediated synchronization abnormality during retrieval between processing of affect-laden events and fact-processing.