803 research outputs found

    Suppressing Unwanted Autobiographical Memories Reduces Their Automatic Influences: Evidence from Electrophysiology and an Implicit Autobiographical Memory Test

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    The present study investigated the extent to which people can suppress unwanted autobiographical memories in a mock crime memory detection context. Participants encoded sensorimotor-rich memories by enacting a lab crime (stealing a ring) and received direct suppression instructions so as to evade guilt detection in a brainwave-based concealed information test. Aftereffects of suppression on automatic memory processes were measured in an autobiographical implicit association test (aIAT). Results showed that suppression attenuated brainwave activity (P300) that is associated with crime-relevant memory retrieval, rendering innocent and guilty/suppression participants indistinguishable. However, guilty/suppression and innocent participants 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. Lastly, extending recent findings that suppression can impair implicit memory processes; we provide novel evidence that suppression reduces automatic cognitive biases that are otherwise associated with actual autobiographical memories

    From Cue to Recall : The Temporal Dynamics of Long-Term Memory Retrieval

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    A fundamental function of long-term memory is the ability to retrieve a specific memory when encountering a retrieval cue. The purpose of this dissertation was to further our understanding of such cued recall by investigating the temporal dynamics from the presentation of the retrieval cue until the target memory is recalled. Retrieval cues are often related with several memories. When such a retrieval cue is presented, the associated memories will compete for retrieval and this retrieval competition needs to be handled in order to retrieve the sought after target memory. Study 1 and Study 2 investigated the temporal dynamics of such competitive semantic cued recall. Interestingly, previous research has shown that the ability to retrieve the currently relevant target memory comes with a cost, namely retrieval-induced forgetting of the competing memories. These studies also investigated the role of competitor activation and target retrieval in this forgetting phenomenon. Study 1 investigated the electrophysiological correlates of reactivation of competing currently irrelevant memories and the role of such competitor activation in retrieval-induced forgetting. Competitor activation was related to an FN400 event-related potential (ERP) effect and this effect predicted increased levels of retrieval-induced forgetting, indicating that this forgetting effect is dependent on competitor activation. Study 2 examined processes involved in target retrieval in a similar competitive semantic cued recall task. The main finding in this study was that attempts to retrieve the target memory were related to a late posterior negativity ERP effect. Another important finding was that behavioural and ERP measures of target retrieval were unrelated to retrieval-induced forgetting. Retrieval cues can sometimes elicit involuntary retrieval of unwanted memories. Such memory intrusions are a core symptom of post-traumatic stress disorder. Study 3 investigated the temporal dynamics of such memory intrusions. One of the key findings was that memory intrusions were related to a negative slow wave ERP effect possibly reflecting the activation of the intruding memory in working memory. Taken together the findings in the dissertation indicate that cued recall involves several cognitive processes ranging from early automatic memory reactivation to conscious processes such as working memory activation and recollection. The findings have implications for cognitive theories of memory and have relevance for several clinical conditions including depression and post-traumatic stress disorder

    Tracking the intrusion of unwanted memories into awareness with event-related potentials

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    Involuntary retrieval of unwanted memories is a common symptom in several clinical disorders, including post-traumatic stress disorder. With an aim to track the temporal dynamics of such memory intrusions, we recorded electrophysiological measures of brain activity while participants engaged in a Think/No-Think task. We presented the left hand word (the cue) of previously encoded word pairs in green or red font. We asked participants to think of the associated right hand word (the associate) when the cue appeared in green (Think condition) and to avoid thinking of the associate when the cue appeared in red (No-Think condition). To isolate cases when participants experienced an intrusive memory, at the end of each trial, participants judged whether the response had come to mind; we classified memories that came to mind during No-Think trials, despite efforts to stop retrieval, as intrusions. In an event-related potential (ERP) analysis, we observed a negative going slow wave (NSW) effect that indexed the duration of a trace in mnemonic awareness; whereas voluntary retrieval and maintenance of the associate was related to a sustained NSW that lasted throughout the 3-s recording epoch, memory intrusions generated short-lived NSWs that were rapidly truncated. Based on these findings, we hypothesize that the intrusion-NSW reflects the associate briefly penetrating working memory. More broadly, these findings exploit the high temporal resolution of ERPs to track the online dynamics of memory intrusions

    Memory control ability modulates intrusive memories after analogue trauma

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    AbstractBackgroundMost people suffer from intrusive memories in the aftermath of trauma. For survivors' well-being, it is key that these intrusions are controlled. Memory control can be exerted through retrieval suppression. Poor retrieval suppression, however, should be associated with persistent distressing intrusions and posttraumatic stress disorder (PTSD). This study tested the hypothesis that individual differences in retrieval suppression predict intrusive memories after trauma. Retrieval suppression was examined with the think/no-think task (TNT) using behavioral and event related potential (ERP) measures.MethodsTwenty-four healthy participants watched a “traumatic” film after performing the TNT task. The frequency and distress of intrusions from the “traumatic” film was measured with an electronic diary. Additionally the Impact of Event Scale (IES) was assessed.ResultsIn line with our hypothesis, behavioral measures of retrieval suppression ability predicted reduced distress ratings for intrusions (r=−.53, p<.01). Further ERP markers of retrieval suppression (a fronto-centrally distributed N2) predicted reduced distress ratings for intrusions (r=−.45, p<.05) and reduced IES Intrusion scores (r=−.56, p<.01).LimitationsThe presented film is a relatively mild stressor as compared to a real-life trauma. Further studies are needed to explore the role of memory control processes for real-life trauma.ConclusionsParticipants with lower retrieval suppression ability exhibited less distressing intrusive memories after analogue trauma. The ERP correlate of retrieval suppression was associated with less distressing intrusive memories and reduced IES Intrusion scores, suggesting that deficient memory control is a potential risk factor for developing PTSD

    The think/no-think alcohol task: a new paradigm for assessing memory suppression in alcohol-related contexts

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    Background Research with the Think/No-Think (TNT) task has shown that voluntary suppression of an unwanted memory may lead to its later forgetting. To date, however, no study has assessed the memory suppression abilities in alcohol-related contexts despite the potential implications that it might have for alcohol research. With this aim, we developed a new version of the TNT paradigm, the TNT Alcohol (TNTA) task, which consists of 36 neutral pictures paired with 36 alcohol/no-alcohol images that are instructed to be suppressed or recollected. Methods Electroencephalographic activity was recorded from 64 electrodes while 20 young healthy females performed the TNTA task. The event-related potentials (ERPs) typically involved in memory suppression/recollection were analyzed, namely the fronto-central N2, the late parietal positivity (LPP), and the frontal slow wave (FSW). Results Findings revealed reduced recall for previously learned images that were subsequently instructed to be suppressed (No-Think) relative to those instructed to be retrieved (Think) and those not cued to be suppressed or retrieved (Baseline). This reduction seemed to be more prominent for alcohol-related memories. In addition, ERP analysis showed that compared to attempts of recollection, attempts of memory suppression were associated with attenuated LPP amplitude-more pronounced for alcohol-related memories-(indicating reduced conscious recollection for No-Think images) as well as with increased FSW (suggesting strategic control aiming at decrease accessibility of unwanted memories). Conclusions These results replicate and extend previously reported behavioral and ERP findings in the TNT paradigm and suggest that the TNTA task may be a useful instrument to measure the ability to suppress alcohol-related memories.This study was supported by the project NORTE-01-0145-FEDER-028672, funded by the Portuguese Foundation for Science and Technology (FCT) and the European Regional Development Fund (FEDER). EL-C and AC were supported by a Postdoctoral Fellowship of the FCT (SFRH/BPD/109750/2015 and SFRH/BPD/91440/2012, respectively), as well as by the Psychology Research Centre (UID/PSI/01662/2013), co-financed by FEDER through COMPETE2020 under the PT2020 Partnership Agreement (POCI-01-0145-FEDER-007653)

    Effects of Long-Term Memory on Visual Attention and Access to Visual Consciousness

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    In dieser Dissertation zeige ich anhand einer Reihe von Beispielen, wie das Langzeitgedächtnis die perzeptuelle Verarbeitung beeinflussen kann. Anhand einer Aufgabe zur visuellen Aufmerksamkeit verdeutliche ich, inwiefern episodische Erinnerungen perzeptuelle Distrakoreffekte reduzieren können. In Experiment 1 sollten Versuchspersonen zuvor gelernte Worte entweder ins Gedächtnis zu rufen oder die Erinnerung an die Worte zu unterdrücken. Anschließend mussten sie unter Zeitdruck neue, bisher nicht präsentierte Worte semantisch einordnen, wobei die Zielworte von den zuvor abgerufenen oder unterdrückten Worten flankiert waren. Da die flankierenden Worte für die semantische Entscheidungsaufgabe irrelevant und die Versuchspersonen instruiert worden waren, diese zu ignorieren, kann von einem perzeptuellen Distraktoreffekt ausgegangen werden. Distraktoreffekte waren für zuvor unterdrückte Gedächtnisinhalte im Vergleich zur abgerufenen Gedächtnisinhalten deutlich reduziert, was nahelegt, dass episodische Gedächtnisinhalte die Wahrnehmung beeinflussen. Auf dieser Erkenntnis aufbauend zeige ich in Experiment 2, wie die suppressionsinduzierte Reduktion der Verarbeitung von Distraktorreizen durch individuelle Differenzen maskiert werden kann. Schließlich wurden den Versuchspersonen in Experiment 3 in einer „Attentional-Blink“-Aufgabe unbekannte Objekte als zweites von zwei aufeinander folgenden Zielobjekten dargeboten. Versuchspersonen konnten Objekte, die mit einer neu gelernten semantischen Information assoziiert waren, besser erkennen als Objekte, die mit minimaler Information assoziiert waren. Dieser Effekt ging mit einer Modulation der ereigniskorrelierten Potenziale 100ms nach Erscheinen des Reizes einher. Diese Ergebnisse zeigen, dass Inhalte aus dem Langzeitgedächtnis Wahrnehmungsprozesse beeinflussen können und leisten damit einen weiteren Beitrag zur Erkenntnis, dass die Wahrnehmung gegenüber höheren Kognitionen nicht unabhängig ist.Numerous studies are emerging which suggest that long-term memories can influence early perceptual processing. Notwithstanding, these finding have come under fire from critics who view perceptual processing as independent of cognition. In this dissertation I demonstrate novel instances of long-term memory effects on perceptual processing, both in the context of an attentional task where I look at the extent to which episodic memory can reduce perceptual distraction and in a conscious detection task where I assess the effect of semantic knowledge on peoples ability to consciously detect briefly presented objects. In experiment one, participants retrieved or suppressed previously memorised words. Following this task, participants made speeded semantic judgments on novel target words that were flanked by the words that had previously undergone suppression or retrieval. Because the flanking words were irrelevant to the semantic judgment and were supposed to be ignored, any influence of their presence on semantic judgment speed can be taken as a marker of perceptual distraction. Results showed that the tendency for flankers to distract from target processing was markedly reduced if those flankers had undergone suppression. In experiment two, I expanded upon this finding by showing how this suppression-induced reduction in distractor processing can be masked by individual differences. Finally, in experiment three, I presented pictures of novel objects to participants as the second of two targets in an attentional blink paradigm. Results showed that participants were able to perceive objects associated with newly acquired semantic knowledge better than objects associated with minimal knowledge, a finding that was associated with a modulation of event-related brain potentials 100 msec after stimulus onset. Taken together, these experiments contribute to the growing body of evidence showing that information from long-term memory can influence perceptual processing

    ERP evidence for the control of emotional memories during strategic retrieval

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    Neural evidence for the strategic retrieval of task-relevant ‘target’ memories at the expense of less relevant ‘nontarget’ memories has been demonstrated across a wide variety of studies. In ERP studies, this evidence consists of the ERP correlate of recollection (i.e. the ‘left parietal old/new effect’) being evident for targets and attenuated for nontargets. It is not yet known, however, whether this degree of strategic control can be extended to emotionally valenced words, or whether these items instead reactivate associated memories. The present study used a paradigm previously employed to demonstrate the strategic retrieval of neutral words (Herron & Rugg, Psychonomic Bulletin and & Review, 10(3), 703-–710, 2003b) to assess the effects of stimulus valence on behavioural and event-related potential (ERP) measures of strategic retrieval. While response accuracy and reaction times associated with targets were unaffected by valence, negative nontargets and new items were both associated with an elevated false alarm rate and longer RTs than their neutral equivalents. Both neutral and negative targets and nontargets elicited early old/new effects between 300 and 500 ms. Critically, whereas neutral and negative targets elicited robust and statistically equivalent left parietal old/new effects between 500 and 800 ms, these were absent for neutral and negative nontargets. A right frontal positivity associated with postretrieval monitoring was evident for neutral targets versus nontargets, for negative versus neutral nontargets, and for targets versus new items. It can therefore be concluded that the recollection of negatively valenced words is subject to strategic control during retrieval, and that postretrieval monitoring processes are influenced by emotional valence

    Inhibitory effects of thought substitution in the think/no-think task: evidence from independent cues

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    When people try not to think about a certain item, they can accomplish this goal by using a thought substitution strategy and think about something else. Research conducted with the think/no-think (TNT) paradigm indicates that such strategy leads subsequently to forgetting the information participants tried not to think about. The present study pursued two goals. First, it investigated the mechanism of forgetting due to thought substitution, contrasting the hypothesis by which forgetting is due to blocking caused by substitutes with the hypothesis that forgetting is due to inhibition (using an independent cue methodology). Second, a boundary condition for forgetting due to thought substitution was examined by creating conditions under which the generation of appropriate substitutes would be impaired. In two experiments, participants completed a TNT task under thought substitution instructions in which either words or pseudo-words were used as original cues and memory was assessed with original and independent cues. The results revealed forgetting in both original and independent cue tests, supporting the inhibitory account of thought substitution, but only when cues were words, and not when they were non-words, pointing to the ineffectiveness of a thought substitution strategy when original cues lack semantic content

    Cognitive control of attention, emotion, and memory : an ERP study

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    Unwanted retrieval of negative memories can be problematic for many clinical populations. The Think/No-Think (T/NT) task (Anderson &amp; Green, 2001) is a new paradigm for studying cognitive control during cued recall. In this task participants view a cue item and are asked to consciously retrieve (think) or interrupt retrieval (no-think) of the associated target item. Eyer (2009) found that self-reported mindfulness was correlated with T/NT cued recall, suggesting a relationship between control of memory retrieval and a general cognitive control skill. The current study measured event-related potentials (ERPs; i.e., electrical brain responses time-locked to cue presentation) for negative and neutral stimuli on the TNT task to assess cognitive control during retrieval. Method: Participants (N = 35) completed questionnaires (e.g., mindfulness, intrusive thoughts) and cognitive tasks related to cognitive control (e.g., attention, working memory span). Then, ERPs were recorded during the TNT task, followed by a final cued recall test. Results: Analyses of ERPs found evidence to support somewhat separable neural networks for control of memory retrieval and for processing the emotional content of the target pictures, with some time windows only exhibiting a main effect of strategy or of emotional valence. However, there was widespread evidence for interactions of these subsystems across a range of time latencies post-cue presentation. Of particular note was a significant Strategy x Valence interaction for the early P1 component (125-164 ms). The overall size of the N2 (250–324 ms) peak was correlated with a wide range of self- report and cognitive test measures of cognitive control at frontal electrode sites. Discussion: The present study adds to knowledge of the timing of control processes during performance of the TNT task through its use of ERP methodology. The effect of the emotional valence of the to-be-recalled target on the early P1 ERP component suggests surprisingly early emotional processing during memory retrieval. The present results also suggest that at least some of the control processes used during the TNT task are part of a larger general-purpose cognitive control system. These results suggest that individual traits provide important and varying influences on the cognitive control of emotional memories
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