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The ability to stop unwanted memories from coming to mind is theorised to be essential for maintaining good mental health. People can employ intentional strategies to prevent conscious intrusions of negative memories, and repeated attempts to stop retrieval both reduces the frequency of intrusions and improves subsequent emotions elicited by those memories. However, it is still unknown whether memory control can improve negative emotions immediately, at the time control is attempted. It is also not clear which strategy is most beneficial for emotion regulation; clearing the mind of any thoughts of negative memories via direct suppression, or substituting memory recall with alternative thoughts. Here, we provide novel evidence that memory control immediately regulates negative emotions associated with autobiographical memories of morally wrong actions. Repeated control significantly improved negative emotions over time, regardless of the strategy used to implement control. Thought substitution involving either positive diversionary thinking or counterfactual thinking both induced positive feelings, whereas direct suppression neutralised emotions, regardless of whether memories were positive or negative. These empirical findings have implications for clinical practice as they indicate that memory control strategies could be effective emotion regulation methods for real-world intrusive memories.

Imagined events can be misremembered as experienced, leading to memory distortions. However, less is known regarding how imagining counterfactual versions of past events can impair existing memories. We addressed this issue, and used EEG to investigate the neurocognitive processes involved when retrieving memories of true events that are associated with a competing imagined event. Participants first performed simple actions with everyday objects (e.g., rolling dice). A week later, they were shown pictures of some of the objects and either imagined the same action they had originally performed, or imagined a counterfactual action (e.g., stacking the dice). Subsequent tests showed that memory for performed actions was reduced after counterfactual imagination when compared to both veridical imagination and a baseline condition that had not been imagined at all, providing novel evidence that counterfactual imagination impairs true memories beyond simple forgetting over time. ERPs and EEG oscillations showed evidence of separate processes associated with memory retrieval versus post-retrieval processes that were recruited to support recall of memories that were challenging to access. The findings show that counterfactual imagination can cause impairments to sensorimotor-rich event memories, and provide new evidence regarding the neurocognitive mechanisms that are recruited when people need to distinguish memories of imagined versus true events.

Some theoretical perspectives suggest people overestimate animals' mental capacities (anthropomorphism), while others suggest the reverse (mind-denial). However, studies have generally not employed objective criteria against which the accuracy or appropriateness of people's judgments about animals can be tested. We employed memory paradigms, in which judgments are clearly right or wrong, in nine experiments (eight preregistered; n = 3,162). When tested shortly after exposure, meat-eaters' memory about companion animals (e.g., dogs) but not food animals (e.g., pigs) showed an anthropomorphic bias: they remembered more information consistent with animals having versus lacking a mind (Experiments 1-4). Vegetarians' and vegans' memory, on the other hand, consistently showed an anthropomorphic bias regarding food and companion animals alike (Experiments 5 and 6). When tested a week after exposure, both those who eat meat and those who do not showed signs of shifting toward a mind-denying bias (Experiments 2, 3, and 6). These biases had important consequences for beliefs about animal minds. Inducing mind-denying memory biases caused participants to see animals as possessing less sophisticated minds (Experiments 7-9). The work demonstrates that memories concerning animals' minds can depart predictably from reality and that such departures can contribute to biased evaluations of their mental capacities. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Our relationships with other animals are governed by how we view their capacity for sentience and suffering. However, there is currently little agreement as to whether people's beliefs about animal minds are largely accurate or inaccurate. We used an innovative task to examine how people update their beliefs in response to noisy but informative clues about animal minds. This allowed us to compare participants' posterior beliefs to what a normative participant ought to believe if they conform to Bayes' theorem. Five studies (four pre-registered; n = 2417) found that participants shifted their beliefs too far in response to clues that suggested animals do not have minds (i.e., overshooting what a normative participant ought to believe), but not far enough in response to clues that suggested animals have minds (i.e., falling short of what a normative participant ought to believe). A final study demonstrated that this effect was attenuated when humans were the targets of belief. The findings demonstrate that people underestimate animal minds in a way that can be said to be inaccurate and highlight the role of belief updating in downplaying evidence of animal minds. The findings are discussed in relation to speciesist beliefs about the supremacy of humans over animals., (Copyright © 2022 The Authors. Published by Elsevier B.V. All rights reserved.)

Remembering unpleasant events can trigger negative feelings. Fortunately, research indicates that unwanted retrieval can be suppressed to prevent memories from intruding into awareness, improving our mental state. The current scientific understanding of retrieval suppression, however, is based mostly on simpler memories, such as associations between words or pictures, which may not reflect how people control unpleasant memory intrusions in everyday life. Here, we investigated the neural and behavioural dynamics of suppressing personal and emotional autobiographical memories using a modified version of the Think/No-Think task. We asked participants to suppress memories of their own past immoral actions, which were hypothesised to be both highly intrusive and motivating to suppress. We report novel evidence from behavioural, ERP, and EEG oscillation measures that autobiographical memory retrieval can be suppressed and suggest that autobiographical suppression recruits similar neurocognitive mechanisms as suppression of simple laboratory associations. Suppression did fail sometimes, and EEG oscillations indicated that such memory intrusions occurred from lapses in sustained control. Importantly, however, participants improved at limiting intrusions with repeated practice. Furthermore, both behavioural and EEG evidence indicated that intentional suppression may be more difficult for memories of our morally wrong actions than memories of our morally right actions. The findings elucidate the neurocognitive correlates of autobiographical retrieval suppression and have implications for theories of morally motivated memory control., (© 2022. The Author(s).)

ERP-based forensic memory detection is based on the logic that guilty suspects will hold incriminating knowledge about crimes they have committed, and therefore should show parietal ERP positivities related to recognition when presented with reminders of their crimes. We predicted that such forensic memory detection might however be inaccurate in older adults, because of changes to recognition-related brain activity that occurs with aging. We measured both ERPs and EEG oscillations associated with episodic old/new recognition and forensic memory detection in 30 younger (age < 30) and 30 older (age > 65) adults. EEG oscillations were included as a complementary measure which is less sensitive to temporal variability and component overlap than ERPs. In line with predictions, recognition-related parietal ERP positivities were significantly reduced in the older compared to younger group in both tasks, despite highly similar behavioural performance. We also observed aging-related reductions in oscillatory markers of recognition in the forensic memory detection test, while the oscillatory effects associated with episodic recognition were similar across age groups. This pattern of results suggests that while both forensic memory detection and episodic recognition are accompanied by aging-induced reductions in parietal ERP positivities, these reductions may be caused by non-overlapping mechanisms across the two tasks. Our findings suggest that EEG-based forensic memory detection tests are less valid in older than younger populations, limiting their practical applications., Competing Interests: Declaration of competing interest All authors declare no conflicts of interest., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Sometimes, we intentionally evaluate stimuli to assess whether we recognize them, whereas, at other times, stimuli automatically elicit recognition despite our efforts to ignore them. If multiple stimuli are encountered in the same environment, intentional recognition judgments can be biased by unintentional recognition of to-be-ignored stimuli. Aging is associated with increased distractibility and impaired intentional retrieval processes, which can make older adults more susceptible to distraction-induced recognition biases. We measured recognition memory performance, event-related potentials (ERPs), and electroencephalography oscillations in old (age range = 60-74) and young (age range = 18-24) adults to investigate how aging affects unintentional and intentional memory processes, and how these processes interact over time to produce distraction-induced recognition biases. Older participants had poorer intentional recognition memory, but the biasing effect of unintentional distractor recognition was similar across age groups. ERP effects related to intentional and unintentional recognition that were strongly expressed in the younger group were reduced or absent in the older group. Furthermore, the older group showed qualitatively different ERP activity during intentional recognition compared with the younger group. However, similar patterns of theta and alpha oscillations were found in both age groups, who showed theta power increases for both intentional and unintentional recognition, whereas alpha power was enhanced for intentional recognition but reduced for unintentional recognition. Overall, the findings show that unintentional and intentional recognition involve multiple dissociable memory processes that have different time-courses and functional characteristics and are differentially affected by aging. Whereas aging has strong effects on the neurocognitive mechanisms underlying intentional recognition memory, unintentional recognition mechanisms are less affected. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Imagining counterfactual versions of past events can distort memory. In 3 experiments, we examined whether imagining a false alibi for a mock crime would make suspects appear less guilty in a concealed memory detection test, the autobiographical Implicit Association Test (aIAT), which aims to determine which of 2 autobiographical events are true. First, "guilty" participants completed a mock crime, whereas "innocent" participants completed an innocent act. Next, some of the guilty participants were asked to imagine a false alibi that corresponded to the innocent act. Finally, all groups completed the aIAT. Across experiments, we varied the type of aIAT used and also compared the effectiveness of the false alibi countermeasure when only imagined once, versus when it was repeatedly imagined over a week-long period. The aIAT accurately detected the mock crime as true for guilty participants without a false alibi, but was consistently less able to detect the mock crime as true for guilty participants who had imagined a false alibi. The findings suggest that if guilty suspects fabricate an alibi, this may create a memory for the alibi that appears to be true based on the aIAT, which is problematic for its real-life applications in concealed memory detection. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Aging is thought to involve impairments to cognitive control functions that support episodic memory, for example by enabling people to strategically constrain their retrieval search towards a specific context ("source") in order to facilitate retrieval of goal-relevant memories. The "memory-for-foils" paradigm investigates source-constrained retrieval by assessing whether incidental encoding of new foils during an old/new recognition test differs depending on the type of processing that was previously used during study of the old items in the test. If it does, it suggests that people process foils differently as a result of engaging in source-constrained retrieval attempts. Young adults typically show differences in incidental encoding foils, but such differences have not been found in older adults. Here, we compared source-constrained retrieval and reward effects on incidental foil encoding between younger and older adults, to assess if age-related reductions in strategic retrieval processing are accompanied by differences in responsiveness to external rewards. The results showed only minor effects of rewards on memory processing, in younger adults only. Contrary to prior findings, older adults had equivalent overall memory performance and spontaneously constrained retrieval to the same extent as the young group, showing that aging-related impairments to strategic retrieval processes are not inevitable.

People can employ adaptive strategies to increase the likelihood that previously encoded information will be successfully retrieved. One such strategy is to constrain retrieval toward relevant information by reimplementing the neurocognitive processes that were engaged during encoding. Using EEG, we examined the temporal dynamics with which constraining retrieval toward semantic versus nonsemantic information affects the processing of new "foil" information encountered during a memory test. Time-frequency analysis of EEG data acquired during an initial study phase revealed that semantic compared with nonsemantic processing was associated with alpha decreases in a left frontal electrode cluster from around 600 msec after stimulus onset. Successful encoding of semantic versus nonsemantic foils during a subsequent memory test was related to decreases in alpha oscillatory activity in the same left frontal electrode cluster, which emerged relatively late in the trial at around 1000-1600 msec after stimulus onset. Across participants, left frontal alpha power elicited by semantic processing during the study phase correlated significantly with left frontal alpha power associated with semantic foil encoding during the memory test. Furthermore, larger left frontal alpha power decreases elicited by semantic foil encoding during the memory test predicted better subsequent semantic foil recognition in an additional surprise foil memory test, although this effect did not reach significance. These findings indicate that constraining retrieval toward semantic information involves reimplementing semantic encoding operations that are mediated by alpha oscillations and that such reimplementation occurs at a late stage of memory retrieval, perhaps reflecting additional monitoring processes.

Background: Lesions of the angular gyrus (AnG) region of human parietal cortex do not cause amnesia, but appear to be associated with reduction in the ability to consciously experience the reliving of previous events., Objectives/hypothesis: We used continuous theta burst stimulation to test the hypothesis that the cognitive mechanism implicated in this memory deficit might be the integration of retrieved sensory event features into a coherent multimodal memory representation., Methods: Healthy volunteers received stimulation to AnG or a vertex control site after studying stimuli that each comprised a visual object embedded in a scene, with the name of the object presented auditorily. Participants were then asked to make memory judgments about the studied stimuli that involved recollection of single event features (visual or auditory), or required integration of event features within the same modality, or across modalities., Results: Participants' ability to retrieve context features from across multiple modalities was significantly reduced after AnG stimulation compared to stimulation of the vertex. This effect was observed only for the integration of cross-modal context features but not for integration of features within the same modality, and could not be accounted for by task difficulty as performance was matched across integration conditions following vertex stimulation., Conclusion: These results support the hypothesis that AnG is necessary for the multimodal integration of distributed cortical episodic features into a unified conscious representation that enables the experience of remembering., (Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.)

The ability to control unwanted memories is critical for maintaining cognitive function and mental health. Prior research has shown that suppressing the retrieval of unwanted memories impairs their retention, as measured using intentional (direct) memory tests. Here, we review emerging evidence revealing that retrieval suppression can also reduce the unintended influence of suppressed traces. In particular, retrieval suppression (a) gradually diminishes the tendency for memories to intrude into awareness and (b) reduces memories' unintended expressions on indirect memory tests. We present a neural account in which, during suppression, retrieval cues elicit hippocampally triggered neocortical activity that briefly reinstates features of the original event, which, in turn, are suppressed by targeted neocortical and hippocampal inhibition. This reactivation-dependent reinstatement principle could provide a broad mechanism by which suppressing retrieval of intrusive memories limits their indirect influences., Competing Interests: Declaration of Conflicting Interests: The authors declared that they had no conflicts of interest with respect to their authorship or the publication of this article.

Distractibility can lead to accidents and academic failures as well as memory problems. Recent evidence suggests that intentional recognition memory can be biased by unintentional recognition of distracting stimuli in the same environment. It is unknown whether unintentional and intentional recognition depend on the same underlying neurocognitive mechanisms. We assessed whether human participants' recognition of previously seen (old) or not seen (new) target stimuli was affected by whether a to-be-ignored distractor was old or new. ERPs were recorded to investigate the neural correlates of this bias. The results showed that the old/new status of salient distractors had a biasing effect on target recognition accuracy. Both intentional and unintentional recognition elicited early ERP effects that are thought to reflect relatively automatic memory processes. However, only intentional recognition elicited the later ERP marker of conscious recollection, consistent with previous suggestions that recollection is under voluntary control. In contrast, unintentional recognition was associated with an enhanced late posterior negativity, which may reflect monitoring or evaluation of memory signals. The findings suggest that unintentional and intentional recognition involve dissociable memory processes.

To remember a previous event, it is often helpful to use goal-directed control processes to constrain what comes to mind during retrieval. Behavioral studies have demonstrated that incidental learning of new "foil" words in a recognition test is superior if the participant is trying to remember studied items that were semantically encoded compared to items that were non-semantically encoded. Here, we applied subsequent memory analysis to fMRI data to understand the neural mechanisms underlying the "foil effect". Participants encoded information during deep semantic and shallow non-semantic tasks and were tested in a subsequent blocked memory task to examine how orienting retrieval towards different types of information influences the incidental encoding of new words presented as foils during the memory test phase. To assess memory for foils, participants performed a further surprise old/new recognition test involving foil words that were encountered during the previous memory test blocks as well as completely new words. Subsequent memory effects, distinguishing successful versus unsuccessful incidental encoding of foils, were observed in regions that included the left inferior frontal gyrus and posterior parietal cortex. The left inferior frontal gyrus exhibited disproportionately larger subsequent memory effects for semantic than non-semantic foils, and significant overlap in activity during semantic, but not non-semantic, initial encoding and foil encoding. The results suggest that orienting retrieval towards different types of foils involves re-implementing the neurocognitive processes that were involved during initial encoding., (Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Research links the medial prefrontal cortex (mPFC) with a number of social cognitive processes that involve reflecting on oneself and other people. Here, we investigated how mPFC might support the ability to recollect information about oneself and others relating to previous experiences. Participants judged whether they had previously related stimuli conceptually to themselves or someone else, or whether they or another agent had performed actions. We uncovered a functional distinction between dorsal and ventral mPFC subregions based on information retrieved from episodic long-term memory. The dorsal mPFC was generally activated when participants attempted to retrieve social information about themselves and others, regardless of whether this information concerned the conceptual or agentic self or other. In contrast, a role was discerned for ventral mPFC during conceptual but not agentic self-referential recollection, indicating specific involvement in retrieving memories related to self-concept rather than bodily self. A subsequent recognition test for new items that had been presented during the recollection task found that conceptual and agentic recollection attempts resulted in differential incidental encoding of new information. Thus, we reveal converging fMRI and behavioral evidence for distinct neurocognitive forms of self-referential recollection, highlighting that conceptual and bodily aspects of self-reflection can be dissociated., (© The Author 2014. Published by Oxford University Press.)

The present study investigated the extent to which people can suppress unwanted autobiographical memories in a memory-detection context involving a mock crime. Participants encoded sensorimotor-rich memories by enacting a lab-based crime (stealing a ring) and received instructions to suppress memory of the crime in order to evade guilt detection in a brain-wave-based concealed-information test. Aftereffects of suppression on automatic memory processes were measured in an autobiographical Implicit Association Test. Results showed that suppression attenuated brain-wave activity (the P300) associated with crime-relevant memory retrieval, which rendered waveforms from innocent and guilty participants indistinguishable. However, the two groups could nevertheless be discriminated via the late-posterior-negative slow wave, which may reflect the need to monitor response conflict arising between voluntary suppression and automatic recognition processes. Finally, extending recent findings that suppression can impair implicit memory processes, we provide novel evidence that suppression reduces automatic cognitive biases often associated with actual autobiographical memories., (© The Author(s) 2015.)

The contribution of lateral parietal regions such as the angular gyrus to human episodic memory has been the subject of much debate following widespread observations of left parietal activity in healthy volunteers during functional neuroimaging studies of memory retrieval. Patients with lateral parietal lesions are not amnesic, but recent evidence indicates that their memory abilities may not be entirely preserved. Whereas recollection appears intact when objective measures such as source accuracy are used, patients often exhibit reduced subjective confidence in their accurate recollections. When asked to recall autobiographical memories, they may produce spontaneous narratives that lack richness and specificity, but can remember specific details when prompted. Two distinct theoretical accounts have been proposed to explain these results: that the patients have a deficit in the bottom-up capturing of attention by retrieval output, or that they have an impairment in the subjective experience of recollection. The present study aimed to differentiate between these accounts using continuous theta burst stimulation (cTBS) in healthy participants to disrupt function of specific left parietal subregions, including angular gyrus. Inconsistent with predictions of the attentional theory, angular gyrus cTBS did not result in greater impairment of free recall than cued recall. Supporting predictions of the subjective recollection account, temporary disruption of angular gyrus was associated with highly accurate source recollection accuracy but a selective reduction in participants' rated source confidence. The findings are consistent with a role for angular gyrus in the integration of memory features into a conscious representation that enables the subjective experience of remembering.

Failing to remember whether we performed, or merely imagined performing, an everyday action can occasionally be inconvenient, but in some circumstances it can have potentially dangerous consequences. In this fMRI study, we investigated the brain activity patterns, and objective and subjective behavioral measures, associated with recollecting such everyday actions. We used an ecologically valid "reality-monitoring" paradigm in which participants performed, or imagined performing, specified actions with real objects drawn from one of two boxes. Lateral brain areas, including prefrontal cortex, were active when participants recollected both the actions that had been associated with objects and the locations from which they had been drawn, consistent with a general role in source recollection. By contrast, medial prefrontal and motor regions made more specific contributions, with supplementary motor cortex activity being associated with recollection decisions about actions but not locations, and medial prefrontal cortex exhibiting greater activity when remembering performed rather than imagined actions. These results support a theoretical interpretation of reality monitoring that entails the fine-grained discrimination between multiple forms of internally and externally generated information.

Brain-activity markers of guilty knowledge have been promoted as accurate and reliable measures for establishing criminal culpability. Tests based on these markers interpret the presence or absence of memory-related neural activity as diagnostic of whether or not incriminating information is stored in a suspect's brain. This conclusion critically relies on the untested assumption that reminders of a crime uncontrollably elicit memory-related brain activity. However, recent research indicates that, in some circumstances, humans can control whether they remember a previous experience by intentionally suppressing retrieval. We examined whether people could use retrieval suppression to conceal neural evidence of incriminating memories as indexed by Event-Related Potentials (ERPs). When people were motivated to suppress crime retrieval, their memory-related ERP effects were significantly decreased, allowing guilty individuals to evade detection. Our findings indicate that brain measures of guilty knowledge may be under criminals' intentional control and place limits on their use in legal settings., (Copyright © 2013 The Authors. Published by Elsevier B.V. All rights reserved.)

Functional MRI research suggests that different frontal and parietal cortical regions support strategic processes that are engaged at different stages of recollection, from pre-retrieval processing of a cue to post-retrieval maintenance and evaluation of recollected information. Whereas some of these regions respond in a domain-general way, other regions are sensitive to the type of information being recollected. However, the low temporal resolution of fMRI cannot distinguish component processes at the time-scale at which recollection occurs. We therefore combined fMRI with the excellent temporal resolution of source localised EEG/MEG to investigate the spatiotemporal neural dynamics of recollection. fMRI and EEG/MEG data were collected from the same participants in two sessions while they retrieved different types of episodic information. This multimodal imaging approach revealed striking consistency between the regions identified with fMRI and EEG/MEG, providing novel evidence of how these brain areas interact over time to support source recollection. For domain-general recollection, results from both modalities converged in showing the strongest activations in medial parietal cortex, which according to EEG/MEG was reliable at a late retrieval stage. Domain-specific source recollection increased fMRI and EEG/MEG activation in the left lateral prefrontal cortex, which EEG/MEG indicated also to be recruited during a post-recollection stage. The findings suggest that although medial parietal and left lateral prefrontal regions mediate functionally different retrieval processes, they are both engaged at a late stage of episodic retrieval., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Interference between competing memories is a major source of retrieval failure, yet, surprisingly little is known about how competitive memory activation arises in the brain. One possibility is that interference during episodic retrieval might be produced by relatively automatic conceptual priming mechanisms that are independent of strategic retrieval processes. Such priming-driven interference might occur when the competing memories have strong pre-existing associations to the retrieval cue. We used ERPs to measure the neural dynamics of retrieval competition, and investigated whether the ERP correlates of interference were affected by varying task demands for selective retrieval. Participants encoded cue words that were presented either two or four times, paired either with the same or different strongly associated words across repetitions. In a subsequent test, participants either selectively recalled each cue's most recent associate, or simply judged how many times a cue had been presented, without requiring selective recall. Interference effects on test performance were only seen in the recall task. In contrast, ERPs during test revealed an early posterior positivity for high interference items that was present in both retrieval tasks. This early ERP effect likely reflects a conceptual priming-related N400 reduction when many associations to a cue were pre-activated. A later parietal positivity resembling the ERP correlate of conscious recollection was found only in the recall task. The results suggest that early effects of proactive interference are relatively automatic and independent of intentional retrieval processes, consistent with suggestions that interference can arise through conceptual priming., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Much recent interest has centered on understanding the relationship between brain structure variability and individual differences in cognition, but there has been little progress in identifying specific neuroanatomical bases of such individual differences. One cognitive ability that exhibits considerable variability in the healthy population is reality monitoring; the cognitive processes used to introspectively judge whether a memory came from an internal or external source (e.g., whether an event was imagined or actually occurred). Neuroimaging research has implicated the medial anterior prefrontal cortex (PFC) in reality monitoring, and here we sought to determine whether morphological variability in a specific anteromedial PFC brain structure, the paracingulate sulcus (PCS), might underlie performance. Fifty-three healthy volunteers were selected on the basis of MRI scans and classified into four groups according to presence or absence of the PCS in their left or right hemisphere. The group with absence of the PCS in both hemispheres showed significantly reduced reality monitoring performance and ability to introspect metacognitively about their performance when compared with other participants. Consistent with the prediction that sulcal absence might mean greater volume in the surrounding frontal gyri, voxel-based morphometry revealed a significant negative correlation between anterior PFC gray matter and reality monitoring performance. The findings provide evidence that individual differences in introspective abilities like reality monitoring may be associated with specific structural variability in the PFC.

There are some past experiences that we would prefer not to remember. Previous research has shown that repeatedly stopping retrieval of an unwanted memory increases the probability of later forgetting of that memory, and engages prefrontal control mechanisms to attenuate activity in the hippocampus. However, the mechanisms of preventing memory retrieval, and how these relate to the later forgetting, are yet to be fully understood. Here we present neural and behavioural evidence that two distinct strategies for retrieval stopping - direct memory suppression and self-distracting thought substitution - contribute to forgetting of unwanted memories in qualitatively different ways. Only direct memory suppression reduced centro-parietal positivity in the event-related potentials (ERP) between 300 and 600 ms post-stimulus, consistent with a reduction in the ERP correlate of recollection. Furthermore, only direct memory suppression produced later inhibitory forgetting that was predicted by an earlier negative ERP effect that may be associated with motor inhibition. In contrast, thought substitution produced later non-inhibitory forgetting and had no effect on the ERP correlate of recollection. Our findings demonstrate the first ERP and behavioural dissociation between inhibitory and non-inhibitory forgetting, and suggest that unwanted memories may be directly suppressed without selective retrieval of alternative memories.

Voluntary control processes can be recruited to facilitate recollection in situations where a retrieval cue fails to automatically bring to mind a desired episodic memory. We investigated whether voluntary control processes can also stop recollection of unwanted memories that would otherwise have been automatically recollected. Participants were trained on cue-associate word-pairs, then repeatedly presented with the cue and asked to either recollect or avoid recollecting the associate, while having the event-related potential (ERP) correlate of conscious recollection measured. Halfway through the phase, some cues switched instructions so that participants had to start avoiding recall of associates they had previously repeatedly recalled, and vice versa. ERPs during recollection avoidance showed a significantly reduced positivity in the correlate of conscious recollection, and switching instructions reversed the ERP effect even for items that had been previously repeatedly recalled, suggesting that voluntary control processes can override highly practiced, automatic recollection. Avoiding recollection of particularly prepotent memories was associated with an additional, earlier ERP negativity that was separable from the later voluntary modulation of conscious recollection. The findings have implications for theories of memory retrieval by highlighting the involvement of voluntary attentional processes in controlling conscious recollection.

We investigated neurocognitive processes of voluntarily avoiding conscious recollection by asking participants to either attempt to recollect (the Think condition) or to avoid recollecting (the No-Think condition) a previously exposed paired associate. Event-related potentials (ERPs) during Think and No-Think trials were separated on the basis of previous learning success versus failure. This separation yielded temporal and topographic dissociations between early ERP effects of a Think versus No-Think strategy, which were maximal between 200 and 300 ms after stimulus presentation and independent of learning status, and a later learning-specific ERP effect maximal between 500 and 800 ms after stimulus presentation. In this later time-window, Learned Think items elicited a larger late left parietal positivity than did Not Learned Think, Learned No-Think, and Not Learned No-Think items; moreover, Learned No-Think and Not Learned Think items did not differ in late left parietal positivity. Because the late left parietal positivity indexes conscious recollection, the results provide firm evidence that conscious recollection of recollectable information can be voluntarily avoided on an item-specific basis and help to clarify previous neural evidence from the Think/No-Think procedure, which could not separate item-specific from strategic processes.