Memory Control Lab - Publications

2018
Justin C. Hulbert, Michael C Anderson (2018) What doesn’t kill you makes you stronger: Psychological trauma and its relationship to enhanced memory control Journal of Experimental Psychology: General Advance online publication.  
Control processes engaged in halting the automatic retrieval of unwanted memories have been shown to reduce the later recallability of the targets of suppression. Like other cognitive skills that benefit from practice, we hypothesized that memory control is similarly experience dependent, such that individuals with greater real-life experience at stopping retrieval would exhibit better inhibitory control over unwanted memories. Across two experiments, we found that college students reporting a greater history of trauma exhibited more suppression-induced forgetting of both negative and neutral memories than did those in a matched group who had reported experiencing little to no trauma. The association was especially evident on a test of suppression-induced forgetting involving independent retrieval cues that are designed to better isolate the effects of inhibitory control on memory. Participants reporting more trauma demonstrated greater generalized forgetting of suppressed material. These findings raise the possibility that, given proper training, individuals can learn to better manage intrusive experiences, and are broadly consistent with the view that moderate adversity can foster resilience later in life.
Yuhua Guo, Taylor W Schmitz, Marieke Mur, Catarina S Ferreira, Michael C Anderson (2018) A supramodal role of the basal ganglia in memory and motor inhibition: Meta-analytic evidence Neuropsychologia 108:8. 117-134. 
The ability to stop actions and thoughts is essential for goal-directed behaviour. Neuroimaging research has revealed that stopping actions and thoughts engage similar cortical mechanisms, including the ventro- and dorso-lateral prefrontal cortex. However, whether and how these abilities require similar subcortical mechanisms remains unexplored. Specifically of interest are the basal ganglia, subcortical structures long-known for their motor functions, but less so for their role in cognition. To investigate the potential common mechanisms in the basal ganglia underlying action and thought stopping, we conducted meta-analyses using fMRI data from the Go/No-Go, Stop-signal, and Think/No-Think tasks. All three tasks require active stopping of prepotent actions or thoughts. To localise basal ganglia activations, we performed high-resolution manual segmentations of striatal subregions. We found that all three tasks recovered clusters in the basal ganglia, although the specific localisation of these clusters differed. Although the Go/No-Go and Stop-signal tasks are often interchangeably used for measuring action stopping, their cluster locations in the basal ganglia did not significantly overlap. These different localised clusters suggest that the Go/No-Go and Stop-signal tasks may recruit distinct basal ganglia stopping processes, and therefore should not be treated equivalently. More importantly, the basal ganglia cluster recovered from the Think/No-Think task largely co-localised with that from the Stop-signal task, but not the Go/No-Go task, possibly indicating that the Think/No-Think and Stop-signal tasks share a common striatal circuitry involved in the cancellation of unwanted thoughts and actions. The greater similarity of the Think/No-Think task to the Stop-Signal rather than Go/No-Go task also was echoed at the cortical level, which revealed highly overlapping and largely right lateralized set of regions including the anterior DLPFC, VLPFC, Pre-SMA and ACC. Overall, we provide novel evidence suggesting not only that the basal ganglia are critical for thought stopping, but also that they are involved in specific stopping subprocesses that can be engaged by tasks in different domains. These findings raise the possibility that the basal ganglia may be part of a supramodal network responsible for stopping unwanted processes more broadly.
2017
Taylor Schmitz, Marta Correia, Catarina Ferreira, Andrew Prescot, Michael C Anderson (2017) Hippocampal GABA enables inhibitory control over unwanted thoughts Nature Communications 8:1311. 1-36. 
Intrusive memories, images, and hallucinations are hallmark symptoms of psychiatric disorders. Although often attributed to deficient inhibitory control by the prefrontal cortex, difficulty in controlling intrusive thoughts is also associated with hippocampal hyperactivity, arising from dysfunctional GABAergic interneurons. How hippocampal GABA contributes to stopping unwanted thoughts is unknown. Here we show that GABAergic inhibition of hippocampal retrieval activity forms a key link in a fronto-hippocampal inhibitory control pathway underlying thought suppression. Subjects viewed reminders of unwanted thoughts and tried to suppress retrieval while being scanned with functional magnetic resonance imaging. Suppression reduced hippocampal activity and memory for suppressed content. 1H magnetic resonance spectroscopy revealed that greater resting concentrations of hippocampal GABA predicted better mnemonic control. Higher hippocampal, but not prefrontal GABA, predicted stronger fronto-hippocampal coupling during suppression, suggesting that interneurons local to the hippocampus implement control over intrusive thoughts. Stopping actions did not engage this pathway. These findings specify a multi-level mechanistic model of how the content of awareness is voluntarily controlled.
Pierre Gagnepain, Justin Hulbert, Michael C Anderson (2017) Parallel Regulation of Memory and Emotion Supports the Suppression of Intrusive Memories The Journal of Neuroscience 37: 6423-6441
Intrusive memories often take the form of distressing images that emerge into a person's awareness, unbidden. A fundamental goal of clinical neuroscience is to understand the mechanisms allowing people to control these memory intrusions and reduce their emotional impact. Mnemonic control engages a right fronto-parietal network that interrupts episodic retrieval by modulating hippocampal activity; less is known, however, about how this mechanism contributes to affect regulation. Here we report evidence in humans (males and females) that stopping episodic retrieval to suppress an unpleasant image triggers parallel inhibition of mnemonic and emotional content. Using functional magnetic resonance imaging, we found that regulation of both mnemonic and emotional content were driven by a shared fronto-parietal inhibitory network, and were predicted by a common profile of MTL down-regulation involving the anterior hippocampus and the amygdala. Critically, effective connectivity analysis confirmed that reduced amygdala activity was not merely an indirect consequence of hippocampal suppression; rather, both the hippocampus and the amygdala were targeted by a top-down inhibitory control signal originating from the dorsolateral prefrontal cortex. This negative coupling was greater when unwanted memories intruded into awareness and needed to be purged. Together, these findings support the broad principle that retrieval suppression is achieved by regulating hippocampal processes in tandem with domain-specific brain regions involved in reinstating specific content, in an activity-dependent fashion.
Kevin van Schie, Michael C Anderson (2017) Successfully controlling intrusive memories is harder when control must be sustained Memory 25: 9. 1201-1216
After unpleasant events, people often experience intrusive memories that undermine their peace of mind. In response, they often suppress these unwanted memories from awareness. Such efforts may fail, however, when inhibitory control demands are high due to the need to sustain control, or when fatigue compromises inhibitory capacity. Here we examined how sustained inhibitory demand affected intrusive memories in the Think/No-Think paradigm. To isolate intrusions, participants reported, trial-by-trial, whether their preceding attempt to suppress retrieval had triggered retrieval of the memory they intended to suppress. Such counter-intentional retrievals provide a laboratory model of the sort of involuntary retrieval that may underlie intrusive memories. Using this method, we found that longer duration trials increased the probability of an intrusion. Moreover, on later No-Think trials, control over intrusions suddenly declined, with longer trial durations triggering more relapses of items that had been previously been purged. Thus, the challenges of controlling retrieval appear to cause a decline in control over time, due to a change in state, such as fatigue. These findings raise the possibility that characteristics often true of people with psychiatric disorders - such as compromised sleep, and increased demand on control - may contribute to difficulties in suppressing intrusive memories.
Andrea Greve, Elisa Cooper, Alexander Kaula, Michael C Anderson, Richard Henson (2017) Does prediction error drive one-shot declarative learning? Journal of memory and language 94: 149-165 
The role of prediction error (PE) in driving learning is well-established in fields such as classical and instrumental conditioning, reward learning and procedural memory; however, its role in human one-shot declarative encoding is less clear. According to one recent hypothesis, PE reflects the divergence between two probability distributions: one reflecting the prior probability (from previous experiences) and the other reflecting the sensory evidence (from the current experience). Assuming unimodal probability distributions, PE can be manipulated in three ways: (1) the distance between the mode of the prior and evidence, (2) the precision of the prior, and (3) the precision of the evidence. We tested these three manipulations across five experiments, in terms of peoples' ability to encode a single presentation of a scene-item pairing as a function of previous exposures to that scene and/or item. Memory was probed by presenting the scene together with three choices for the previously paired item, in which the two foil items were from other pairings within the same condition as the target item. In Experiment 1, we manipulated the evidence to be either consistent or inconsistent with prior expectations, predicting PE to be larger, and hence memory better, when the new pairing was inconsistent. In Experiments 2a-c, we manipulated the precision of the priors, predicting better memory for a new pairing when the (inconsistent) priors were more precise. In Experiment 3, we manipulated both visual noise and prior exposure for unfamiliar faces, before pairing them with scenes, predicting better memory when the sensory evidence was more precise. In all experiments, the PE hypotheses were supported. We discuss alternative explanations of individual experiments, and conclude the Predictive Interactive Multiple Memory Signals (PIMMS) framework provides the most parsimonious account of the full pattern of results.
Xiaoqing Hu, Zara M Bergström, Pierre Gagnepain, Michael C Anderson (2017) Suppressing Unwanted Memories Reduces Their Unintended Influences. Current directions in psychological science 26: 2. 197-206 
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.
Matthew D Sacchet, Benjamin J Levy, J Paul Hamilton, Arkadiy Maksimovskiy, Paula T Hertel, Jutta Joormann, Michael C Anderson, Anthony D Wagner, Ian H Gotlib (2017) Cognitive and neural consequences of memory suppression in major depressive disorder. Cognitive, affective & behavioral neuroscience 17: 1. 77-93 
Negative biases in cognition have been documented consistently in major depressive disorder (MDD), including difficulties in the ability to control the processing of negative material. Although negative information-processing biases have been studied using both behavioral and neuroimaging paradigms, relatively little research has been conducted examining the difficulties of depressed persons with inhibiting the retrieval of negative information from long-term memory. In this study, we used the think/no-think paradigm and functional magnetic resonance imaging to assess the cognitive and neural consequences of memory suppression in individuals diagnosed with depression and in healthy controls. The participants showed typical behavioral forgetting effects, but contrary to our hypotheses, there were no differences between the depressed and nondepressed participants or between neutral and negative memories. Relative to controls, depressed individuals exhibited greater activity in right middle frontal gyrus during memory suppression, regardless of the valence of the suppressed stimuli, and differential activity in the amygdala and hippocampus during memory suppression involving negatively valenced stimuli. These findings indicate that depressed individuals are characterized by neural anomalies during the suppression of long-term memories, increasing our understanding of the brain bases of negative cognitive biases in MDD.
2016
Roland G Benoit, Daniel J Davies, Michael C Anderson (2016) Reducing future fears by suppressing the brain mechanisms underlying episodic simulation Proceedings of the National Academy of Sciences 113: 52. 
Imagining future events conveys adaptive benefits, yet recurrent simulations of feared situations may help to maintain anxiety. In two studies, we tested the hypothesis that people can attenuate future fears by suppressing anticipatory simulations of dreaded events. Participants repeatedly imagined upsetting episodes that they feared might happen to them and suppressed imaginings of other such events. Suppressing imagination engaged the right dorsolateral prefrontal cortex, which modulated activation in the hippocampus and in the ventromedial prefrontal cortex (vmPFC). Consistent with the role of the vmPFC in providing access to details that are typical for an event, stronger inhibition of this region was associated with greater forgetting of such details. Suppression further hindered participants’ ability to later freely envision suppressed episodes. Critically, it also reduced feelings of apprehensiveness about the feared scenario, and individuals who were particularly successful at down-regulating fears were also less trait-anxious. Attenuating apprehensiveness by suppressing simulations of feared events may thus be an effective coping strategy, suggesting that a deficiency in this mechanism could contribute to the development of anxiety.
Robin Hellerstedt, Mikael Johansson, Michael C Anderson (2016) Tracking the intrusion of unwanted memories into awareness with event-related potentials Neuropsychologia 89: 510-523 
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.
Michael C Anderson, Jamie G Bunce, Helen Barbas (2016) Prefrontal-hippocampal pathways underlying inhibitory control over memory Neurobiology of Learning and Memory 134: 145-161 
A key function of the prefrontal cortex is to support inhibitory control over behavior. It is widely believed that this function extends to stopping cognitive processes as well. Consistent with this, mounting evidence establishes the role of the right lateral prefrontal cortex in a clear case of cognitive control: retrieval suppression. Retrieval suppression refers to the ability to intentionally stop the retrieval process that arises when a reminder to a memory appears. Functional imaging data indicates that retrieval suppression involves top-down modulation of hippocampal activity by the dorsolateral prefrontal cortex, but the anatomical pathways supporting this inhibitory modulation remain unclear. Here we bridge this gap by integrating key findings about retrieval suppression observed through functional imaging with a detailed consideration of relevant anatomical pathways observed in non-human primates. Focusing selectively on the potential role of the anterior cingulate cortex, we develop two hypotheses about the pathways mediating interactions between lateral prefrontal cortex and the medial temporal lobes during suppression, and their cellular targets: the entorhinal gating hypothesis, and thalamo-hippocampal modulation via the nucleus reuniens. We hypothesize that whereas entorhinal gating is well situated to stop retrieval proactively, thalamo-hippocampal modulation may interrupt an ongoing act of retrieval reactively. Isolating the pathways that underlie retrieval suppression holds the potential to advance our understanding of a range of psychiatric disorders characterized by persistent intrusive thoughts. More broadly, an anatomical account of retrieval suppression would provide a key model system for understanding inhibitory control over cognition.
J C Hulbert, R N Henson, Michael C Anderson (2016) Inducing amnesia through systemic suppression Nature Communications 7. 
Hippocampal damage profoundly disrupts the ability to store new memories of life events. Amnesic windows might also occur in healthy people due to disturbed hippocampal function arising during mental processes that systemically reduce hippocampal activity. Intentionally suppressing memory retrieval (retrieval stopping) reduces hippocampal activity via control mechanisms mediated by the lateral prefrontal cortex. Here we show that when people suppress retrieval given a reminder of an unwanted memory, they are considerably more likely to forget unrelated experiences from periods surrounding suppression. This amnesic shadow follows a dose-response function, becomes more pronounced after practice suppressing retrieval, exhibits characteristics indicating disturbed hippocampal function, and is predicted by reduced hippocampal activity. These findings indicate that stopping retrieval engages a suppression mechanism that broadly compromises hippocampal processes and that hippocampal stabilization processes can be interrupted strategically. Cognitively triggered amnesia constitutes an unrecognized forgetting process that may account for otherwise unexplained memory lapses following trauma.
Markus Streb, Axel Mecklinger, Michael C Anderson, Lass-Hennemann Johanna, Tanja Michael (2016) Memory control ability modulates intrusive memories after analogue trauma. Journal of affective disorders 192: 134-42 
BACKGROUND Most 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. METHODS Twenty-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. RESULTS In line with our hypothesis, behavioral measures of retrieval suppression ability predicted reduced distress ratings for intrusions (r=-.53, p\textless.01). Further ERP markers of retrieval suppression (a fronto-centrally distributed N2) predicted reduced distress ratings for intrusions (r=-.45, p\textless.05) and reduced IES Intrusion scores (r=-.56, p\textless.01). LIMITATIONS The 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. CONCLUSIONS Participants 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.
Tianliang Yang, Xu Lei, Michael C Anderson (2016) Decreased inhibitory control of negative information in directed forgetting. International journal of psychophysiology : official journal of the International Organization of Psychophysiology 100: 44-51 
A great deal of evidence suggests that emotion enhances memory. Thus, it may be harder to forget emotional information. By means of fMRI, this question was investigated in the item-method directed forgetting paradigm. Behavioral results demonstrated that although all kinds of material could be forgotten, negative words showed reduced directed forgetting effect. At the neural level, the initial viewing of negative words elicited increased activities in inferior frontal gyrus and superior parietal lobule when contrasted with neutral words, which reflected the capture of attention by negative content. Forgetting instructions for negative and neutral words led to enhanced activations in frontal and parietal cortex, consistent with the engagement of an active inhibitory process. Surprisingly, whereas successful directed forgetting of neutral words elicited stronger activations in right middle frontal gyrus compared with incidental forgetting, no such activation was observed for negative words. The lack of activation for negative words may be due to an attentional bias in processing negative words, which may briefly interfere with the deployment of inhibitory control. The present findings are consistent with the engagement of an active forgetting mechanism that contributes to the item-method directed forgetting. However, evidence of impeded inhibitory control suggests that forgetting negative words is harder.
2015
Charlotte L Rae, Laura E Hughes, Michael C Anderson, James B Rowe (2015) The prefrontal cortex achieves inhibitory control by facilitating subcortical motor pathway connectivity. The Journal of neuroscience : the official journal of the Society for Neuroscience 35: 2. 786-94 
Communication between the prefrontal cortex and subcortical nuclei underpins the control and inhibition of behavior. However, the interactions in such pathways remain controversial. Using a stop-signal response inhibition task and functional imaging with analysis of effective connectivity, we show that the lateral prefrontal cortex influences the strength of communication between regions in the frontostriatal motor system. We compared 20 generative models that represented alternative interactions between the inferior frontal gyrus, presupplementary motor area (preSMA), subthalamic nucleus (STN), and primary motor cortex during response inhibition. Bayesian model selection revealed that during successful response inhibition, the inferior frontal gyrus modulates an excitatory influence of the preSMA on the STN, thereby amplifying the downstream polysynaptic inhibition from the STN to the motor cortex. Critically, the strength of the interaction between preSMA and STN, and the degree of modulation by the inferior frontal gyrus, predicted individual differences in participants' stopping performance (stop-signal reaction time). We then used diffusion-weighted imaging with tractography to assess white matter structure in the pathways connecting these three regions. The mean diffusivity in tracts between preSMA and the STN, and between the inferior frontal gyrus and STN, also predicted individual differences in stopping efficiency. Finally, we found that white matter structure in the tract between preSMA and STN correlated with effective connectivity of the same pathway, providing important cross-modal validation of the effective connectivity measures. Together, the results demonstrate the network dynamics and modulatory role of the prefrontal cortex that underpin individual differences in inhibitory control.
Brendan D Murray, Michael C Anderson, Elizabeth A Kensinger (2015) Older adults can suppress unwanted memories when given an appropriate strategy. Psychology and Aging 30: 1. 9-25. 
Memory suppression refers to the ability to exclude distracting memories from conscious awareness, and this ability can be assessed with the think/no-think paradigm. Recent research with older adults has provided evidence suggesting both intact and deficient memory suppression. The present studies seek to understand the conditions contributing to older adults' ability to suppress memories voluntarily. We report 2 experiments indicating that the specificity of the think/no-think task instructions contributes to older adults' suppression success: When older adults receive open-ended instructions that require them to develop a retrieval suppres- sion strategy on their own, they show diminished memory suppression compared with younger adults. Conversely, when older adults receive focused instructions directing them to a strategy thought to better isolate inhibitory control, they show suppression-induced forgetting similar to that exhibited by younger adults. Younger adults demonstrate memory suppression regardless of the specificity of the instructions given, suggesting that the ability to select a successful suppression strategy spontaneously may be compromised in older adults. If so, this deficit may be associated with diminished control over unwanted memories in naturalistic settings if impeded strategy development reduces the successful deployment of inhibitory control.
Ana Catarino, Charlotte S Küpper, Aliza Werner-Seidler, Tim Dalgleish, Michael C Anderson (2015) Failing to forget : inhibitory-control deficits compromise memory suppression in posttraumatic stress disorder. Psychological science 26: 5. 604-16 
Most people have experienced distressing events that they would rather forget. Although memories of such events become less intrusive with time for the majority of people, those with posttraumatic stress disorder (PTSD) are afflicted by vivid, recurrent memories of their trauma. Often triggered by reminders in the daily environment, these memories can cause severe distress and impairment. We propose that difficulties with intrusive memories in PTSD arise in part from a deficit in engaging inhibitory control to suppress episodic retrieval. We tested this hypothesis by adapting the think/no-think paradigm to investigate voluntary memory suppression of aversive scenes cued by naturalistic reminders. Retrieval suppression was compromised significantly in PTSD patients, compared with trauma-exposed control participants. Furthermore, patients with the largest deficits in suppression-induced forgetting were also those with the most severe PTSD symptoms. These results raise the possibility that prefrontal mechanisms supporting inhibitory control over memory are impaired in PTSD.
Maria Wimber, Arjen Alink, Ian Charest, Nikolaus Kriegeskorte, Michael C Anderson (2015) Retrieval induces adaptive forgetting of competing memories via cortical pattern suppression. Nature neuroscience 18: 4. 582-9. 
Remembering a past experience can, surprisingly, cause forgetting. Forgetting arises when other competing traces interfere with retrieval and inhibitory control mechanisms are engaged to suppress the distraction they cause. This form of forgetting is considered to be adaptive because it reduces future interference. The effect of this proposed inhibition process on competing memories has, however, never been observed, as behavioral methods are 'blind' to retrieval dynamics and neuroimaging methods have not isolated retrieval of individual memories. We developed a canonical template tracking method to quantify the activation state of individual target memories and competitors during retrieval. This method revealed that repeatedly retrieving target memories suppressed cortical patterns unique to competitors. Pattern suppression was related to engagement of prefrontal regions that have been implicated in resolving retrieval competition and, critically, predicted later forgetting. Thus, our findings demonstrate a cortical pattern suppression mechanism through which remembering adaptively shapes which aspects of our past remain accessible.
Roland G Benoit, Justin C Hulbert, Ean Huddleston, Michael C Anderson (2015) Adaptive Top-Down Suppression of Hippocampal Activity and the Purging of Intrusive Memories from Consciousness Journal of Cognitive Neuroscience 27: 1. 96-111 
Unexpected changes in the location of a target for an upcoming action require both attentional reorienting and motor planning update. In both macaque and human brain, the medial posterior parietal cortex is involved in both phenomena but its causal role is still unclear. Here we used on-line rTMS over the putative human V6A (pV6A), a reach-related region in the dorsal part of the anterior bank of the parieto-occipital sulcus, during an attention and a reaching task requiring covert shifts of attention and planning of reaching movements toward cued targets in space. We found that rTMS increased RTs to invalidly cued but not to validly cued targets during both the attention and reaching task. Furthermore, we found that rTMS induced a deviation of reaching endpoints toward visual fixation and that this deviation was larger for invalidly cued targets. The results suggest that reorienting signals are used by human pV6A area to rapidly update the current motor plan or the ongoing action when a behaviorally relevant object unexpectedly occurs in an unattended location. The current findings suggest a direct involvement of the action-related dorso-medial visual stream in attentional reorienting and a more specific role of pV6A area in the dynamic, on-line control of reaching actions.
Jonathan M Fawcett, Roland G Benoit, Pierre Gagnepain, Amna Salman, Savani Bartholdy, Caroline Bradley, Daniel K Y Chan, Ayesha Roche, Chris R Brewin, Michael C Anderson (2015) The origins of repetitive thought in rumination : separating cognitive style from deficits in inhibitory control over memory. Journal of behavior therapy and experimental psychiatry 47: 1-8 
BACKGRBACKGROUND AND OBJECTIVES
RuminaRumination is a major contributor to the maintenance of affective disorders and has been linked to memory control deficits. However, ruminators often report intentionally engaging in repetitive thought due to its perceived benefits. Deliberate re-processing may lead to the appearance of a memory control deficit that is better explained as a difference in cognitive style.
METHODS
Ninety-six undergraduate students volunteered to take part in a direct-suppression variant of the Think/No-Think paradigm after which they completed self-report measures of rumination and the degree to which they deliberately re-processed the to-be-suppressed items.
RESULTS
We demonstrate a relation between rumination and impaired suppression-induced forgetting. This relation is robust even when controlling for deliberate re-processing of the to-be-suppressed items, a behavior itself related to both rumination and suppression. Therefore, whereas conscious fixation on to-be-suppressed items reduced memory suppression, it did not fully account for the relation between rumination and memory suppression.
LIMITATIONS
The current experiment employed a retrospective measure of deliberate re-processing in the context of an unscreened university sample; future research might therefore generalize our findings using an online measure of deliberate re-processing or within a clinical population.
CONCLUSIONS
We provide evidence that deliberate re-processing accounts for some -but not all- of the relation between rumination and suppression-induced forgetting. The present findings, observed in a paradigm known to engage top-down inhibitory modulation of mnemonic processing, provide the most theoretically focused evidence to date for the existence of a memory control deficit in rumination.
2014
Michael C Anderson, Simon Hanslmayr (2014) Neural mechanisms of motivated forgetting. Trends in cognitive sciences 18: 6. 279-92 
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.
Pierre Gagnepain, Richard N Henson, Michael C Anderson (2014) Suppressing unwanted memories reduces their unconscious influence via targeted cortical inhibition. Proceedings of the National Academy of Sciences of the United States of America 111: 13. 
Suppressing retrieval of unwanted memories reduces their later conscious recall. It is widely believed, however, that suppressed memories can continue to exert strong unconscious effects that may compromise mental health. Here we show that excluding memories from awareness not only modulates medial temporal lobe regions involved in explicit retention, but also neocortical areas underlying unconscious expressions of memory. Using repetition priming in visual perception as a model task, we found that excluding memories of visual objects from consciousness reduced their later indirect influence on perception, literally making the content of suppressed memories harder for participants to see. Critically, effective connectivity and pattern similarity analysis revealed that suppression mechanisms mediated by the right middle frontal gyrus reduced activity in neocortical areas involved in perceiving objects and targeted the neural populations most activated by reminders. The degree of inhibitory modulation of the visual cortex while people were suppressing visual memories predicted, in a later perception test, the disruption in the neural markers of sensory memory. These findings suggest a neurobiological model of how motivated forgetting affects the unconscious expression of memory that may be generalized to other types of memory content. More generally, they suggest that the century-old assumption that suppression leaves unconscious memories intact should be reconsidered.
Charlotte L Rae, Laura E Hughes, Chelan Weaver, Michael C Anderson, James B Rowe (2014) Selection and stopping in voluntary action : a meta-analysis and combined fMRI study. NeuroImage 86: 381-91 
Voluntary action control requires selection of appropriate responses and stopping of inappropriate responses. Selection and stopping are often investigated separately, but they appear to recruit similar brain regions, including the pre-supplementary motor area (preSMA) and inferior frontal gyrus. We therefore examined the evidence for overlap of selection and stopping using two approaches: a meta-analysis of existing studies of selection and stopping, and a novel within-subject fMRI study in which action selection and a stop signal task were combined factorially. The novel fMRI study also permitted us to investigate hypotheses regarding a common mechanism for selection and stopping. The preSMA was identified by both methods as common to selection and stopping. However, stopping a selected action did not recruit preSMA more than stopping a specified action, nor did stop signal reaction times differ significantly across the two conditions. These findings suggest that the preSMA supports both action selection and stopping, but the two processes may not require access to a common inhibition mechanism. Instead, the preSMA might represent information about potential actions that is used in both action selection and stopping in order to resolve conflict between competing available responses.
Charlotte S Küpper, Roland G Benoit, Tim Dalgleish, Michael C Anderson (2014) Direct suppression as a mechanism for controlling unpleasant memories in daily life. Journal of experimental psychology. General 143: 4. 1443-9 
Suppressing unwanted memories can impair their later recall. Recent work shows that this forgetting is achieved by at least two mechanisms supported by distinct neural systems: thought substitution and direct suppression (Benoit & Anderson, 2012). Here, we examined whether direct suppression, thought to be achieved by down-regulation of hippocampal activity, can disrupt memory of aversive scenes, and, if so, whether this disruption is linked to people's perception of their ability to control intrusive thoughts. We presented participants with strong naturalistic reminders to aversive scenes and asked them to either covertly retrieve or directly suppress the associated scenes. Later, participants were cued with the reminders and asked to recall the scenes in detail. Direct suppression reduced recall probability of the scenes and also reduced the number of details recalled, even when scenes were remembered. Deficits in recall arose for minor details but also for details central to each scene's gist. Participants with higher self-perceived control abilities over intrusive thoughts showed greater forgetting than did those reporting lower levels of control. These findings suggest that inhibitory processes underlying direct suppression can disrupt retention of aversive visual memories and link those processes to individual differences in control over intrusive thoughts in everyday life. These findings reinforce the possibility that inhibition may be less efficient in people likely to acquire posttraumatic stress disorder in the wake of a traumatic experience.
Christopher J Schilling, Benjamin C Storm, Michael C Anderson (2014) Examining the costs and benefits of inhibition in memory retrieval. Cognition 133: 2. 358-70 
Inhibitory control is thought to serve an adaptive function in controlling behavior, with individual differences predicting variation in numerous cognitive functions. However, inhibition is more properly construed as inducing both benefits and costs to performance. Benefits arise at the point when inhibition prevents expression of an unwanted or contextually inappropriate response; costs arise later, when access to the inhibited representation is required by other processes. Here we illustrate how failure to consider both the costs and benefits of inhibition has generated confusion in the literature on individual differences in cognitive control. Using retrieval-induced forgetting as a model case, we illustrate this by showing that changing the way that retrieval-induced forgetting is measured to allow greater expression of the benefits of inhibition together with the costs can reduce and even reverse the theoretically predicted correlation between motor and memory inhibition. Specifically, we show that when the final test in a retrieval-induced forgetting procedure employs item-specific cues (i.e., category-plus-stem cued recall and item-recognition) that better isolate the lingering costs of inhibition, better motor response inhibition (faster stop-signal reaction times) predicts greater retrieval-induced forgetting. In striking contrast, when the final test is less well controlled, allowing both the costs and benefits of inhibition to contribute, motor response inhibition has the opposite relationship with retrieval-induced forgetting. These findings underscore the importance of considering the correlated costs and benefits problem when studying individual differences in inhibitory control. More generally, they suggest that a shared inhibition mechanism may underlie people's ability to control memories and actions.
2013
Pedro M Paz-Alonso, Silvia A Bunge, Michael C Anderson, Simona Ghetti (2013) Strength of coupling within a mnemonic control network differentiates those who can and cannot suppress memory retrieval. The Journal of neuroscience : the official journal of the Society for Neuroscience 33: 11. 5017-26 
The ability to direct our thought processes influences not only what we do, but also what we remember later. Here we sought to identify the brain network that supports the ability to control memory retrieval and to understand the neural basis of age-related changes and individual differences in the capacity for mnemonic control. To this end, we collected functional MRI data from 43 children and young adults while they attempted to retrieve or suppress retrieval of previously learned associations. Seed-based functional connectivity analyses revealed a largely right-lateralized dorsolateral prefrontal cortex-cingulate-parietal-hippocampal network that exhibited strongly correlated activity during retrieval suppression. Regardless of age, individuals who were able to suppress memory retrieval exhibited tighter coupling between key nodes in this dorsolateral prefrontal cortex-cingulate-parietal-hippocampal network than individuals who did not. Further, only those capable of mnemonic control exhibited tighter coupling during successful retrieval suppression (intentional forgetting) than during unsuccessful retrieval (unintentional forgetting). Across both children and adults, individual differences in retrieval suppression were best explained by the strength of these network interactions.
Peter D Weller, Michael C Anderson, Carlos J Gómez-Ariza, M Teresa Bajo (2013) On the status of cue independence as a criterion for memory inhibition : evidence against the covert blocking hypothesis. Journal of experimental psychology. Learning, memory, and cognition 39: 4. 1232-45 
Retrieving memories can impair recall of other related traces. Items affected by this retrieval-induced forgetting (RIF) are often less accessible when tested with independent probes, a characteristic known as cue independence. Cue independence has been interpreted as evidence for inhibitory mechanisms that suppress competing items during retrieval (M. C. Anderson & Spellman, 1995). Several authors, however, have proposed that apparent cue independence might instead reflect noninhibitory cue-dependent blocking mechanisms. In this view, when participants receive an independent probe test, they do not limit themselves to those probes but instead recall study cues covertly to aid performance. This strategy is thought to be self-defeating, because it reintroduces cues that instigate blocking, lending the appearance of generalized inhibition. M. C. Anderson (2003), in contrast, proposed that covert cuing masks cue-independent forgetting by providing a compound cuing advantage. Here, we replicated cue-independent RIF and documented how access to the original study cues influences this effect. In Experiments 1-2, we found that overtly providing category cues on independent probe tests never increased RIF. Indeed, when we provided categories selectively for items that should suffer the most blocking, a sizable reversal of RIF occurred, consistent with the masking hypothesis. Simply asking participants to covertly retrieve categories eliminated cue-independent RIF, contradicting predictions of the self-inflicted blocking account. Far from causing cue-independent forgetting, covert cuing masks it. These findings strongly support the inhibition account of RIF and, importantly, may explain why cue-independent forgetting is not always found.
Kevin van Schie, Elke Geraerts, Michael C Anderson (2013) Emotional and non-emotional memories are suppressible under direct suppression instructions. Cognition & emotion 27: 6. 1122-31. 
Research on retrieval suppression has produced varying results concerning whether negatively valenced memories are more or less suppressible than neutral memories. This variability may arise if, across studies, participants adopt different approaches to memory control. Cognitive and neurobiological research points to two mechanisms that achieve retrieval suppression: thought-substitution and direct suppression (Benoit & Anderson, 2012; Bergström, de Fockert, & Richardson-Klavehn, 2009). Using the Think/No-think paradigm, this study examined whether participants can inhibit neutral and negatively valenced memories, using a uniform direct suppression strategy. Importantly, when strategy was controlled, negative and neutral items were comparably inhibited. Participants reported high compliance with direct suppression instructions, and success at controlling awareness predicted forgetting. These findings provide the first evidence that direct suppression can impair negatively valenced events, and suggest that variability in forgetting negative memories in prior studies is unlikely to arise from difficulty using direct suppression to control emotionally negative experiences.
Zara M Bergström, Michael C Anderson, Marie Buda, Jon S Simons, Alan Richardson-Klavehn (2013) Intentional retrieval suppression can conceal guilty knowledge in ERP memory detection tests. Biological psychology 94: 1. 1-11 
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.
2012
Roland G Benoit, Michael C Anderson (2012) Opposing Mechanisms Support the Voluntary Forgetting of Unwanted Memories Neuron 76: 2. 450-460. 
Reminders of the past can trigger the recollection of events that one would rather forget. Here, using fMRI, we demonstrate two distinct neural mechanisms that foster the intentional forgetting of such unwanted memories. Both mechanisms impair long-term retention by limiting momentary awareness of the memories, yet they operate in opposite ways. One mechanism, direct suppression, disengages episodic retrieval through the systemic inhibition of hippocampal processing that originates from right dorsolateral prefrontal cortex (PFC). The opposite mechanism, thought substitution, instead engages retrieval processes to occupy the limited focus of awareness with a substitute memory. It is mediated by interactions between left caudal and midventrolateral PFC that support the selective retrieval of substitutes in the context of prepotent, unwanted memories. These findings suggest that we are not at the mercy of passive forgetting; rather, our memories can be shaped by two opposite mechanisms of mnemonic control.
Benjamin J Levy, Michael C Anderson (2012) Purging of Memories from Conscious Awareness Tracked in the Human Brain Journal of Neuroscience 32: 47. 16785-16794 
Understanding the neural basis of conscious experience and its regulation are fundamental goals of science. While recent research has made substantial progress in identifying the neural correlates of conscious experiences, it remains unclear how individuals exert control over the contents of awareness. In particular, can a memory that has entered the aware state be purged from consciousness if it is not currently desired? Here we tracked the correlates of consciousness in humans using functional magnetic resonance imaging and demonstrated the involvement of a downregulation mechanism that purges contents from conscious awareness. When individuals tried to prevent the retrieval of a memory in response to reminders, hippocampal activity was reduced, as previously established. Crucially, using trial-by-trial reports of phenomenal awareness, we found that this reduction of hippocampal activation was specifically associated with moments when a memory involuntarily intruded into conscious awareness and needed to be purged. This downregulation of activity during memory intrusions appears to disrupt momentary awareness of unwanted contents and, importantly, predicts impaired recall of the memory on later tests. These results tie the voluntary control of phenomenal awareness to observable changes in neural activity linked to awareness, and so provide a neurobiological model for guiding inquiry into the physical foundations of control over consciousness.
Ean Huddleston, Michael C Anderson (2012) Reassessing critiques of the independent probe method for studying inhibition. Journal of experimental psychology. Learning, memory, and cognition 38: 5. 1408-18 
Inhibitory processes have been proposed to play an important role in resolving interference during retrieval (M. C. Anderson, 2003; M. C. Anderson & Spellman, 1995). Supporting this view, retrieval induces a negative aftereffect on competing items known as retrieval-induced forgetting (M. C. Anderson, Bjork, & Bjork, 1994). Retrieval-induced forgetting often generalizes to novel cues used to test the forgotten items, and this cue independence is considered diagnostic of inhibition. This interpretation of cue independence assumes, however, that these novel cues (i.e., independent probes) are truly independent of the original cues. Challenging this assumption, Camp, Pecher, Schmidt, and Zeelenberg (2009) reported that extralist cuing test performance can be influenced by increasing the accessibility of other nonpresented cues. Here we consider this evidence for nonindependence and the conditions under which it occurs. We present two experiments demonstrating that this cue enhancement effect arises exclusively whenever independent probes have uncontrolled semantic relationships to the study cues of the sort that are specifically proscribed by the method-relationships not at all detected by association norms. When such relationships are controlled, as they are in many studies of inhibition, cue enhancement effects disappear. These findings highlight the importance of carefully controlling probe-cue relatedness in research on cue-independent forgetting and suggest that cue independence is diagnostic of inhibition.
Justin C Hulbert, Geeta Shivde, Michael C Anderson (2012) Evidence against associative blocking as a cause of cue-independent retrieval-induced forgetting. Experimental psychology 59: 1. 11-21. 
Selectively retrieving an item from long-term memory reduces the accessibility of competing traces, a phenomenon known as retrieval-induced forgetting (RIF). RIF exhibits cue independence, or the tendency for forgetting to generalize to novel test cues, suggesting an inhibitory basis for this phenomenon. An alternative view (Camp, Pecher, & Schmidt, 2007; Camp et al., 2009; Perfect et al., 2004) suggests that using novel test cues to measure cue independence actually engenders associative interference when participants covertly supplement retrieval with practiced cues that then associatively block retrieval. Accordingly, the covert-cueing hypothesis assumes that the relative strength of the practiced items at final test - and not the inhibition levied on the unpracticed items during retrieval practice - underlies cue-independent forgetting. As such, this perspective predicts that strengthening practiced items by any means, even if not via retrieval practice, should induce forgetting. Contrary to these predictions, however, we present clear evidence that cue-independent forgetting is induced by retrieval practice and not by repeated study exposures. This dissociation occurred despite significant, comparable levels of strengthening of practiced items in each case, and despite the use of Anderson and Spellman's original (1995) independent probe method criticized by covert-cueing theorists as being especially conducive to associative blocking. These results demonstrate that cue-independent RIF is unrelated to the strengthening of practiced items, and thereby fail to support a key prediction of the covert-cueing hypothesis. The results, instead, favor a role of inhibition in resolving retrieval interference.
Michael C Anderson, Ean Huddleston (2012) Towards a Cognitive and Neurobiological Model of Motivated Forgetting In: True and False Recovered Memories. Nebraska Symposium on Motivation  Edited by:Robert F Belli.  53-120 New York, NY: Springer. 
Historically, research on forgetting has been dominated by the assumption that forgetting is passive, reflecting decay, interference, and changes in context. This emphasis arises from the pervasive assumption that forgetting is a negative outcome. Here, we present a functional view of forgetting in which the fate of experience in memory is determined as much by motivational forces that dictate the focus of attention as it is by passive factors. A central tool of motivated forgetting is retrieval suppression, a process whereby people shut down episodic retrieval to control awareness. We review behavioral, neurobiological, and clinical research and show that retrieval suppression leads us to forget suppressed experiences. We discuss key questions necessary to address to develop this model, relationships to other forgetting phenomena, and the implications of this research for understanding recovered memories. This work provides a foundation for understanding how motivational forces influence what we remember of life experience.
2011
Brice A Kuhl, Michael C Anderson (2011) More is not always better : paradoxical effects of repetition on semantic accessibility. Psychonomic bulletin & review 18: 5. 964-72 
Repetition normally enhances memory. While in some cases the benefit of added repetition may be incremental, few would expect that massed repetition could actually reverse the benefits of brief repetition. Here we report two experiments that document a clear example of a paradoxical effect of massed repetition. Subjects first repeated words (e.g., "sheep") aloud one at a time for 0, 5, 10, 20, or 40 s. A free association phase followed in which cues could be completed with repeated words (e.g., "herd s___" for "sheep") or with semantically associated words (e.g., "fabric w___" for "wool"). Brief periods of repetition (5-10 s) resulted in priming, as would be expected based on research on repetition priming and spreading activation. Longer periods of repetition (20-40 s), however, abolished priming. Interestingly, this massed-repetition decrement was particularly robust for semantic associates of repeated words, and was evident after a 15-min delay. These findings document a paradoxical feature of the effects of rehearsal on memory: When ideas are repeated often enough, the benefits of rehearsal can actually be reversed.
Michael C Anderson, Julia Reinholz, Brice A Kuhl, Ulrich Mayr (2011) Intentional suppression of unwanted memories grows more difficult as we age. Psychology and aging 26: 2. 397-405 
People often encounter reminders to memories that they would prefer not to think about. When this happens, they often try to exclude the unwanted memory from awareness, a process that relies upon inhibitory control. We propose that the ability to regulate awareness of unwanted memories through inhibition declines with advancing age. In two experiments, we examined younger and older adults' ability to intentionally suppress retrieval when repeatedly confronted with reminders to an experience they were instructed to not think about. Older adults exhibited significantly less forgetting of the suppressed items compared to younger adults on a later independent probe test of recall, indicating that older adults failed to inhibit the to-be-avoided memories. These findings demonstrate that the ability to intentionally regulate conscious awareness of unwanted memories through inhibitory control declines with age, highlighting differences in memory control that may be of clinical relevance in the aftermath of unpleasant life events.
Geeta Shivde, Michael C Anderson (2011) On the existence of semantic working memory : evidence for direct semantic maintenance. Journal of experimental psychology. Learning, memory, and cognition 37: 6. 1342-70 
Despite widespread acknowledgment of the importance of online semantic maintenance, there has been astonishingly little work that clearly establishes this construct. We review the extant work relevant to short-term retention of meaning and show that, although consistent with semantic working memory, most data can be accommodated in other ways. Using a new concurrent probe paradigm, we then report experiments that implicate a semantic maintenance capacity that is independent of phonological or visual maintenance that may build on a mechanism of direct semantic maintenance. Experiments 1 through 5 established that while subjects maintain the meaning of a word, a novel delay-period marker of semantic retention, the semantic relatedness effect, is observed on a concurrent lexical decision task. The semantic relatedness effect refers to slowed response times when subjects make a lexical decision to a probe that is associatively related to the idea they are maintaining, compared to when the probe is unrelated. The semantic relatedness effect occurred for semantic but not for phonological or visual word-form maintenance, dissipated quickly after maintenance ends, and survived concurrent articulatory suppression. The effect disappeared when subjects performed our immediate memory task with a long-term memory strategy rather than with active maintenance. Experiment 6 demonstrated a parallel phonological relatedness effect that occurs for phonological but not semantic maintenance, establishing a full double dissociation between the effects of semantic and phonological maintenance. These findings support a distinct semantic maintenance capacity and provide a behavioral marker through which semantic working memory can be studied.
Leilani B Goodmon, Michael C Anderson (2011) Semantic integration as a boundary condition on inhibitory processes in episodic retrieval. Journal of experimental psychology. Learning, memory, and cognition 37: 2. 416-36 
Recalling an experience often impairs the later retention of related traces, a phenomenon known as retrieval-induced forgetting (RIF). Research has shown that episodic associations protect competing memories from RIF (Anderson & McCulloch, 1999). We report 4 experiments that examined whether semantic associations also protect against RIF. In all experiments, robust RIF occurred when there were few associations between practiced and nonpracticed sets, but RIF was abolished when there were many. The benefits of semantic integration were independent of episodic integration strategies and were not mediated by intentional use of the associations. Rather, these results establish a new boundary condition on RIF-semantic integration-that has a potent impact on the magnitude of RIF and may explain variability in the RIF phenomenon.
2010
Michael C Anderson, B J Levy (2010) On the relationship between interference and inhibition in cognition In: Successful Remembering and Successful Forgetting : A Festschrift in Honor of Robert A. Bjork  Edited by:A S Benjamin.  107-132 New York: Taylor & Francis. 
In this chapter, we consider inhibition as a response to unwanted accessibility. First, we review the evidence for a relationship between the degree of interference caused by a trace and inhibitory aftereffects observed on later retention tests for that trace. This evidence is highly consistent with the idea that inhibitory mechanisms are triggered in response to intrusive memories that might otherwise disrupt our current goals. As such, inhibition apperas to be a key mechanism for achieving functional forgetting. We then consider the theoretical relationship between interefence and inhibition, and what this relationship predicts about the expected afterefects of inhibition. We introduce the concept of a demand-success trade-off, a crucial factor complicating the measurement of inhibition. Demand-success trade-offs have important consequences for testing theoretical models of inhibition as well as theories that posit inhibitory deficits in different populations. These trade-offs are not unique to memory research, but affect any domain concerned with inhibition. By drawing attention to this issue, we hope to prevent confusion and theoretical controvery in the literature on inhibition, and improve the assessment of inhibitory deficits in special populations.
2009
Elvira Garcia-Bajos, Malen Migueles, Michael C Anderson (2009) Script knowledge modulates retrieval-induced forgetting for eyewitness events. Memory 17: 1. 92-103 
To determine the influence of knowledge schemata on inhibitory processes we analysed how the typicality of the actions of an event modulated retrieval-induced forgetting (RIF). Participants were presented with a realistic videotape of a bank robbery. Based on a normative study, high- and low-typicality actions of the event were determined. After watching the video, participants practised retrieving either half of the high- or half of the low-typicality actions, and their performance was compared against a no-practice control group. Tests given immediately after the event and after a 1-week retention interval demonstrated significant RIF for low-typicality actions exclusively when low-typicality actions were practised, but a comparable forgetting effect did not emerge for highly schematic actions. These findings confirm that highly integrated script knowledge protects high-typicality actions of an event from inhibitory processes, and demonstrate that RIF's effects last far longer than has been previously found.
Pedro M Paz-Alonso, Simona Ghetti, Bryan J Matlen, Michael C Anderson, Silvia A Bunge (2009) Memory suppression is an active process that improves over childhood. Frontiers in human neuroscience 3: September. 
We all have memories that we prefer not to think about. The ability to suppress retrieval of unwanted memories has been documented in behavioral and neuroimaging research using the Think/No-Think (TNT) paradigm with adults. Attempts to stop memory retrieval are associated with increased activation of lateral prefrontal cortex (PFC) and concomitant reduced activation in medial temporal lobe (MTL) structures. However, the extent to which children have the ability to actively suppress their memories is unknown. This study investigated memory suppression in middle childhood using the TNT paradigm. Forty children aged 8-12 and 30 young adults were instructed either to remember (Think) or suppress (No-Think) the memory of the second word of previously studied word-pairs, when presented with the first member as a reminder. They then performed two different cued recall tasks, testing their memory for the second word in each pair after the TNT phase using the same first studied word within the pair as a cue (intra-list cue) and also an independent cue (extra-list cue). Children exhibited age-related improvements in memory suppression from age 8 to 12 in both memory tests, against a backdrop of overall improvements in declarative memory over this age range. These findings suggest that memory suppression is an active process that develops during late childhood, likely due to an age-related refinement in the ability to engage PFC to down-regulate activity in areas involved in episodic retrieval.
Michael C Anderson, Benjamin J Levy (2009) Suppressing Unwanted Memories Current Directions in Psychological Science 18: 4. 189-194 
When reminded of something we would prefer not to think about, we often try to exclude the unwanted memory from awareness. Recent research indicates that people control unwanted memories by stopping memory retrieval, using mechanisms similar to those used to stop reflexive motor responses. Controlling unwanted memories is implemented by the lateral prefrontal cortex, which acts to reduce activity in the hippocampus, thereby impairing retention of those memories. Individual differences in the efficacy of these systems may underlie variation in how well people control intrusive memories and adapt in the aftermath of trauma. This research supports the existence of an active forgetting process and establishes a neurocognitive model for inquiry into motivated forgetting.
2008
K E Flegal, Michael C Anderson (2008) Overthinking skilled motor performance : Or why those who teach can't do. Psychonomic bulletin & review 15: 5. 927-932. 
Skilled athletes often maintain that overthinking disrupts performance of their motor skills. Here, we examined whether these experiences have a basis in verbal overshadowing, a phenomenon in which describing memories for ineffable perceptual experiences disrupts later retention. After learning a unique golf-putting task, golfers of low and intermediate skill either described their actions in detail or performed an irrelevant verbal task. They then performed the putting task again. Strikingly, describing their putting experience significantly impaired higher skill golfers' ability to reachieve the putting criterion, compared with higher skill golfers who performed the irrelevant verbal activity. Verbalization had no such effect, however, for lower skill golfers. These findings establish that the effects of overthinking extend beyond dual-task interference and may sometimes reflect impacts on long-term memory. We propose that these effects are mediated by competition between procedural and declarative memory, as suggested by recent work in cognitive neuroscience.
Benjamin J Levy, Michael C Anderson (2008) Individual differences in the suppression of unwanted memories : the executive deficit hypothesis. Acta psychologica 127: 3. 623-35 
When confronted with reminders to an unpleasant memory, people often try to prevent the unwanted memory from coming to mind. In this article, we review behavioral and neurocognitive evidence concerning the consequences of exerting such control over memory retrieval. This work indicates that suppressing retrieval is accomplished by control mechanisms that inhibit the unwanted memories, making them harder to recall later, even when desired. This process engages executive control mechanisms mediated by the lateral prefrontal cortex to terminate recollection-related activity in the hippocampus. Together, these findings specify a neurocognitive model of how memory control operates, suggesting that executive control may be an important means of down-regulating intrusive memories over time. We conclude by proposing that individual differences in the regulation of intrusive memories in the aftermath of trauma may be mediated by pre-existing differences in executive control ability. In support of this executive deficit hypothesis, we review the recent work indicating links between executive control ability and memory suppression.
Justin C Hulbert, Michael C Anderson (2008) The Role of Inhibition in Learning In: Acta psychiatrica Belgica 7-20. 
Forgetting has long been relegated to the backseat in discussions of learning. Classically, forgetting was thought to result either from a slow decay caused by disuse or, as Muller and Pilzecker (1900) proposed, as a passive consequence of learning new material that interferes with the old. In contrast, we adopt a functional view of forgetting. As outlined by Anderson (2003), we argue that forgetting is largely a consequence not of learning, per se, but of the executive control processes recruited to resolve response competition arising during memory retrieval. In this chapter, we summarize the ways in which the forgetting associated with one important facet of executive control—inhibition—actually facilitates learning.
2007
Benjamin J Levy, Nathan D McVeigh, Alejandra Marful, Michael C Anderson (2007) Inhibiting your native language : the role of retrieval-induced forgetting during second-language acquisition. Psychological science 18: 1. 29-34 
After immersion in a foreign language, speakers often have difficulty retrieving native-language words-a phenomenon known as first-language attrition. We propose that first-language attrition arises in part from the suppression of native-language phonology during second-language use, and thus is a case of phonological retrieval-induced forgetting. In two experiments, we investigated this hypothesis by having native English speakers name visual objects in a language they were learning (Spanish). Repeatedly naming the objects in Spanish reduced the accessibility of the corresponding English words, as measured by an independent-probe test of inhibition. The results establish that the phonology of the words was inhibited, as access to the concepts underlying the presented objects was facilitated, not impaired. More asymmetry between English and Spanish fluency was associated with more inhibition for native-language words. This result supports the idea that inhibition plays a functional role in overcoming interference during the early stages of second-language acquisition.
Michael C Anderson (2007) Inhibition : Manifestations in long-term memory In: Science of memory : Concepts  Edited by:H L Roediger, Y Dudai, S M Fitzpatrick.  295-300 New York: Oxford University Press. 
In this chapter, I discuss the idea that inhibition functions to regulate the accessibility of unwanted traces in memory. In the first section, I provide a brief overview of key theoretical attributes of inhibition, and my general perspective on the functions that this process serves in memory. I then illustrate these functions and attributes with examples from research on the role of inhibitory control in forgetting.
Michael C Anderson, Benjamin J Levy (2007) Theoretical issues in inhibition : Insights from research on human memory. In: Inhibition in cognition.  Edited by:D S Gorfein, C M MacLeod.  81-102 Washington, DC: American Psychological Association. 
In this chapter we discuss evidence that uniquely supports this inhibitory control perspective in two response override situations in memory: the desire to stop retrieval, and the need to selectively retrieve a memory. Then we describe a theoretical problem in the measurement of inhibition that is almost always ignored in studies of inhibition. This issue, the correlated costs and benefits problem, has extremely important consequences for the ability to adequately test theoretical models of inhibition, and, importantly, for the ability to test inhibitory deficit theories concerning different populations of subjects. We argue that in order to make a strong claim in any study about the presence or absence of inhibition, or about variations in the magnitude of inhibition as a function of condition or population, it is necessary to include an independent probe of the impaired items’ accessibility. Without this, measurements of inhibition will suffer the correlated costs and benefits problem, precluding principled predictions about how behavioral effects should vary according to inhibitory theories. This problem is not at all unique to memory research, and examples of the problem in research on executive control, visual selective attention, and language processing will be provided. By drawing attention to this issue, we hope to steer the field toward experiments that isolate the involvement of inhibitory mechanisms in the control of memory retrieval and prevent the unnecessary confusion and theoretical controversy in the literature on inhibitory processes.
Michael C Anderson (2007) Rimozione: un approccio dalle neuroscienze cognitive. In: Psicoanalisi e Neuroscienze  Mancia M. (eds).  Milano: Springer, Milano. 
Sono passati più di cento anni da quando Freud ha affermato che i ricordi possono essere dimenticati spingendoli nell’inconscio, e ha chiamato rimozione questo processo. L’esistenza di questo meccanismo è sempre rimasta in discussione, perché si tratta di un fenomeno fortemente connesso a esperienze traumatiche e per le difficoltà etiche e pratiche che sorgono quando si tenta di studiarlo in esperimenti controllati. Sulla stampa popolare, persone che non credono ai ricordi rimossi hanno definito la rimozione un “mito”, un pezzo di folclore clinico privo di basi nella realtà, un processo per il quale non esiste alcun meccanismo psicologico scientificamente valido. Ma la rimozione, o almeno un comportamento che le assomiglia, viene invece riscontrata spesso, nel rapporto con i pazienti, dagli psicoanalisti e da altri professionisti della salute mentale. Colpisce la distanza tra questi punti di vista sulla rimozione: una distanza che riflette una perdurante disconnessione tra coloro che affermano di osservare il fenomeno o i suoi effetti e coloro che ribadiscono la necessità di precisare e valutare questo costrutto con il massimo rigore. Nel campo della psicologia, sono possibili due modi di comportarsi in presenza di tale persistente conflitto: continuare a seguire tradizioni e opinioni contrastanti, senza risolvere il problema, oppure ricomporre le divergenze tra le diverse prospettive specificando i meccanismi della rimozione in base ai dati empirici sempre più numerosi sui meccanismi neurali e cognitivi della memoria, e facendo in modo che la rimozione sia testabile sperimentalmente. Ma è mai possibile una scienza della rimozione?
2006
Michael C Anderson, Benjamin J Levy (2006) Encouraging the nascent cognitive neuroscience of repression Behavioral and Brain Sciences 29: 05.  511-513. 
Repression has remained controversial for nearly a century on account of the lack of well-controlled evidence validating it. Here we argue that the conceptual and methodological tools now exist for a rigorous scientific examination of repression, and that a nascent cognitive neuroscience of repression is emerging. We review progress in this area and highlight important questions for this field to address.
Michael C Anderson (2006) Repression : A cognitive neuroscience approach In: Neuroscience and Psychoanalysis  Edited by:M Mancia.  327-350 Milan: Springer. 
In this chapter, I review a program of research that I have been pursuing now for over a decade that may reconcile these dissociated views. A central strategy I have pursued has been to consider how repression might be understood in terms of mechanisms that are widely studied in cognitive psychology and cognitive neuroscience. To this end, I have focused on a well-specified question: what are the mechanisms by which human beings willfully control awareness of unwanted memories, when confronted with reminders to them? Although my colleagues and I view this question through the lens of cognitive psychology, the situation bears a strong resemblance to repression. Thus, a better understanding of memory control may provide both the theoretical and empirical grounding necessary to make repression a scientifically tractable problem. The resulting theory may not be identical to Freudian repression, but it clearly speaks to the situations characterized by Freud. First,I describe our general theoretical perspective,and the behavioral and neurobiological evidence that supports it. I then discuss how these constructs relate to Freudian repression.
2005
Michael C Anderson (2005) The Role of Inhibitory Control in Forgetting Unwanted Memories : A Consideration of Three Methods In: Dynamic Cognitive Processes  Edited by:N Ohta, C M MacLeod, B Uttl.  159-189 Tokyo: Springer-Verlag. 
When confronted with reminders to things that we would pre- fer not to think about, we often attempt to put the unwanted memories out of awareness. Here, I argue that the ability to control memory is a special case of a broad class of situations thought to require executive control: re- sponse override. In such situations, one must stop a strong habitual re- sponse to a stimulus due to situational demands, a function thought to be accomplished by inhibitory processes that suppress the response, enabling more flexible, context-sensitive control over behavior. Recent behavioral studies show that inhibitory mechanisms that control overt behavior are also targeted at declarative memories to control retrieval. Recent neuroi- maging findings (Anderson et al., 2004) further establish that controlling awareness of unwanted memories is associated with increased dorsolateral prefrontal cortex activation, reduced hippocampal activation, and impaired retention of the unwanted trace and that the magnitude of activation in pre- frontal cortex predicts memory suppression. These findings indicate that cognitive and neural systems that support our ability to override prepotent responses can be recruited to override declarative memory retrieval, and that this cognitive act leads to memory failure. The relation between these findings and those obtained with the directed forgetting procedure is also discussed.
2004
Michael C Anderson, Kevin N Ochsner, Brice Kuhl, Jeffrey Cooper, Elaine Robertson, Susan W Gabrieli, Gary H Glover, John D E Gabrieli (2004) Neural systems underlying the suppression of unwanted memories. Science 303: 5655.   232-5
Over a century ago, Freud proposed that unwanted memories can be excluded from awareness, a process called repression. It is unknown, however, how repression occurs in the brain. We used functional magnetic resonance imaging to identify the neural systems involved in keeping unwanted memories out of awareness. Controlling unwanted memories was associated with increased dorsolateral prefrontal activation, reduced hippocampal activation, and impaired retention of those memories. Both prefrontal cortical and right hippocampal activations predicted the magnitude of forgetting. These results confirm the existence of an active forgetting process and establish a neurobiological model for guiding inquiry into motivated forgetting.
Sarah K Johnson, Michael C Anderson (2004) The role of inhibitory control in forgetting semantic knowledge. Psychological science 15: 7. 448-53.
Previous research has shown that episodic retrieval recruits inhibitory processes that impair memory for related events. We report two experiments examining whether inhibitory processes may also be involved in causing semantic memory lapses. In a semantic retrieval-practice paradigm, subjects were given trials presenting a cue (a homograph in Experiment 1, a category in Experiment 2) linked to many different items in semantic memory. For each cue, subjects used general knowledge to generate no (baseline), one, four, or eight different items of semantic knowledge. Afterward, we determined through an apparently unrelated free-association test whether a critical nonpracticed concept associated to the cue had been inhibited. Both experiments found that generating items from semantic memory suppressed competing concepts, and that this impairment was cue independent. These findings show that inhibitory control processes overcome interference during semantic retrieval and that recruitment of these processes may contribute to semantic forgetting.
2003
Michael C Anderson (2003) Rethinking interference theory : Executive control and the mechanisms of forgetting Journal of Memory and Language 49: 4.415-445. 
Interference provides an account of one of the most basic problems in the science of memory: forgetting. Historically, theories of this process were shaped by models of associative learning prevalent when interference research began. In this article, I argue that we should reconsider the long-standing conceptualization of interference as a learning phenomenon and reframe interference as arising from systems that achieve mental and behavioral control. Specifically, it is argued that forgetting is not a passive side effect of storing new memories, but results from inhibitory control mechanisms recruited to override prepotent responses. In support of this idea, I discuss two control situations in which response override is necessary - selection and stopping - and show how these situations have direct parallels in retrieval. I then review evidence that in both of these situations, the need to override prepotent, distracting memories is supported by inhibitory mechanisms that ultimately cause forgetting. The theoretical properties of these inhibitory effects are outlined, along with critical factors known to modulate or mask inhibition. The relation between this executive control theory of forgetting and classical accounts of interference is discussed. © 2003 Published by Elsevier Inc.
2002
Michael C Anderson, Benjamin J Levy (2002) Repression can (and should) be studied empirically: Reply from Anderson and Levy. Trends in cognitive sciences 6: 12. 505-03.
Replies to comments by J. F. Kihlstrom rd/2002-11091-004">(see record 2002-11091-004) on the article by B. J. Levy and M. C. Anderson (see record 2002-17290-004) which described developments in the study of the self-regulation of memory. Kihlstrom disagreed that the work reported by Levy and Anderson has relevance for understanding Freudian repression. The authors maintain that not all scholars believe that Freud intended repression to be an exclusively unconscious process. It is argued that the authors' findings have clear relevance for motivated forgetting. Furthermore, it is not useful to classify repression as a myth and to discourage scientists from careful inquiry into its properties.
Benjamin J Levy, Michael C Anderson (2002) Inhibitory processes and the control of memory retrieval. Trends in cognitive sciences 6: 7. 299-305.
People are often confronted with reminders of things they would prefer not to think about. When this happens, they often attempt to put the unwanted memories out of awareness. Recent research shows that the capacity to suppress distracting traces is mediated by executive-control processes that are analogous to those involved in overriding prepotent motor responses, and it is these processes that cause persisting memory failures for the suppressed items. There is evidence that memory retrieval and motor tasks that are likely to demand executive control recruit overlapping neural mechanisms, suggesting that a common process mediates control in these domains. Together, these findings indicate that memory failures often arise from the mechanisms that lie at the heart of our capacity to influence the focus of thought.
2001
Michael C Anderson, C Green (2001) Suppressing unwanted memories by executive control. Nature 410: 6826. 366-369. 
Freud proposed that unwanted memories can be forgotten by pushing them into the unconscious, a process called repression. The existence of repression has remained controversial for more than a century, in part because of its strong coupling with trauma, and the ethical and practical difficulties of studying such processes in controlled experiments. However, behavioural and neurobiological research on memory and attention shows that people have executive control processes directed at minimizing perceptual distraction, overcoming interference during short and long-term memory tasks and stopping strong habitual responses to stimuli. Here we show that these mechanisms can be recruited to prevent unwanted declarative memories from entering awareness, and that this cognitive act has enduring consequences for the rejected memories. When people encounter cues that remind them of an unwanted memory and they consistently try to prevent awareness of it, the later recall of the rejected memory becomes more difficult. The forgetting increases with the number of times the memory is avoided, resists incentives for accurate recall and is caused by processes that suppress the memory itself. These results show that executive control processes not uniquely tied to trauma may provide a viable model for repression.
Michael C Anderson, Theodore Bell (2001) Forgetting our facts: the role of inhibitory processes in the loss of propositional knowledge. Journal of experimental psychology. General 130: 3. 544-70
Seven experiments are reported that show that retrieving facts from long-term memory is accomplished, in part, by inhibitory processes that suppress interfering facts. When asked to repeatedly retrieve a recently learned proposition (e.g., recalling The actor is looking at the tulip, given cues such as Actor looking t__), subjects experienced a recall deficit for related facts (e.g., The actor is looking at the violin) on a recall test administered 15 min later. Importantly, this retrieval-induced forgetting was shown to generalize to other facts in which the inhibited concepts took part (e.g., The teacher is lifting the violin), replicating a finding observed by M. C. Anderson and B. A. Spellman (1995) with categorical stimuli. These findings suggest a critical role for suppression in models of propositional retrieval and implicate the mere retrieval of what we know as a source of forgetting of factual knowledge.
Michael C Anderson (2001) Active forgetting: Evidence for functional inhibition as a source of memory. Journal of Aggression, Maltreatment & Trauma 4: 2. 185-210
Forgetting is often assumed to be a passive process. A program of research in theoretical memory is reviewed that shows how many instances of ordinary forgetting arise from active inhibitory processes that serve a very important attentional function: selective retrieval. These inhibitory processes have been shown to cause long-lasting forgetting of "distracting" memories that interfere during our attempts to retrieve a particular fact or event. It is argued that these inhibitory processes may form the basis of some instances of traumatic forgetting, and that they provide a mechanistic account of an important phenomenon in the study of amnesia for childhood sexual abuse: the greater incidence of forgetting for betrayal traumas than for abuse perpetrated by strangers.
Geeta Shivde, Michael C Anderson (2001) The role of inhibition in meaning selection: Insights from retrieval-induced forgetting. In: On the consequences of meaning selection : Perspectives on resolving lexical ambiguity  Edited by:D S Gorfein.  175-190 Washington, DC: American Psychological Association. 
If a general attentional inhibition process contributes to meaning selection, then inhibitory phenomena in nonlanguage contexts may yield insights into how inhibition operates during meaning selection. In this chapter, we explore this possibility with work on inhibitory processes in memory retrieval. Although the analogy between attentional selection and lexical ambiguity resolution seems apt, there are substantial differences in the cognitive situations posed by the negative priming paradigm and by lexical ambiguity resolution. Although a common mechanism may be involved, one might wonder whether the properties of negative priming and meaning selection need map onto one another. To the extent that meaning selection can be seen as a special case of retrieval, work on inhibition in long-term memory may provide a closer analogy. In our work on retrieval, we have focused considerable effort on excluding noninhibitory alternatives by developing new methodologies for isolating inhibition. In the first section, we review our work on inhibitory processes in memory retrieval and the findings that have led us to conclude that inhibition is at work. In the second section, we present studies in which we apply these methods to a paradigm relevant to ambiguity resolution.
2000
Michael C Anderson, E L Bjork, Robert A Bjork (2000) Retrieval-induced forgetting : evidence for a recall-specific mechanism. Psychonomic bulletin & review 7: 3.  522-30 
Previous work has shown that recalling information from long-term memory can impair the long-term retention of related representations--a phenomenon known as retrieval-induced forgetting (M. C. Anderson et al, 1994). The authors report an experiment in which the question of whether retrieval is necessary to induce this form of impairment was examined. Ss were 64 undergraduates. All the Ss studied 6 members from each of 8 taxonomic categories (e.g., fruit orange). In the competitive practice condition, the Ss practiced recalling 3 of the 6 members, using category-stem cues (e.g., fruit or___). In the noncompetitive practice condition, the Ss were reexposed to these same members for the same number of repetitions but were asked to recall the category name by using the exemplar and a stem as cues (e.g., fr___ orange). Despite significant and comparable facilitation of practiced items in both conditions, only the competitive practice Ss were impaired in their ability to recall the nonpracticed members on a delayed cued-recall test. These findings argue that retrieval-induced forgetting is not caused by increased competition arising from the strengthening of practiced items, but by inhibitory processes specific to the situation of recall.
Michael C Anderson, Collin Green, Kathleen C McCulloch (2000) Similarity and inhibition in long-term memory : evidence for a two-factor theory. Journal of experimental psychology. Learning, memory, and cognition 26: 5.  1141-59 
Recalling a past experience often requires the suppression of related memories that compete with the retrieval target, causing memory impairment known as retrieval-induced forgetting. Two experiments examined how retrieval-induced forgetting varies with the similarity of the competitor and the target item (target-competitor similarity) and with the similarity between the competitors themselves (competitor-competitor similarity). According to the pattern-suppression model (M. C. Anderson & B. A. Spellman, 1995), high target-competitor similarity should reduce impairment, whereas high competitor-competitor similarity should increase it. Both predictions were supported: Encoding target-competitor similarities not only eliminated retrieval-induced forgetting but also reversed it, whereas encoding competitor-competitor similarities increased impairment. The differing effects of target-competitor and competitor-competitor similarity may resolve conflicting results concerning the effects of similarity on inhibition.
1999
Michael C Anderson, Kathleen C McCulloch (1999) Integration as a general boundary condition on retrieval-induced forgetting. Journal of Experimental Psychology : Learning, Memory, and Cognition 25: 3. 608-629. 
When people form connections between several memories that share a common retrieval cue, the tendency for those memories to interfere with one another during later retrieval attempts is often eliminated. Three experiments examined whether forming such connections might also protect memories from retrieval-induced forgetting, the phenomenon in which retrieving some associates of a cue leads to the suppression of others that interfere during retrieval (M. C. Anderson, E. L. Bjork, & R. A. Bjork, 1994). All 3 experiments found that instructing subjects to interrelate category exemplars during an initial study phase reduced retrieval-induced forgetting. Postexperimental questionnaires indicated that even when people were not instructed to interrelate exemplars, they often did so spontaneously and that this spontaneous integration also protected people from impairment. These findings, together with others obtained in different experimental settings, suggest that complex knowledge structures composed of highly interconnected components may be especially resistant to retrieval-induced forgetting.
1998
Elizabeth Ligon Bjork, Robert A Bjork, Michael C Anderson (1998) Varieties of goal-directed forgetting In: Intentional forgetting : Interdisciplinary approaches  Edited by:J M Golding, C M MacLeod.  103-137 Mahwah, NJ: Lawrence Erlbaum Associates. 
Our goal in this chapter is to examine several varieties of what might be termed goal-directed forgetting-that is, situations where forgetting serves some implicit or explicit personal need. Specifically, we summarize the evidence that a particular mechanism-retrieval inhibition-is common to these several situations, and we speculate on some broader implications of retrieval inhibition as a forgetting mechanism.
1996
Michael C Anderson, James H Neely (1996) InterferenceInterference and inhibition in memory retrieval In: Memory. Handbook of perception and cognition  Edited by:Elizabeth L Bjork, Robert A Bjork.  237-311 San Diego, CA: Academic Press. 
The present chapter reviews what experimental research has revealed about the causes of memory interference and the breadth of situations in which these mechanisms operate. We describe this research in four main sections. First, we discuss some widely held assumptions about the situation of interference, focusing on the idea taht such efffects arise from competition for access via a shared retrieval cue. This notion is sufficiently general that it may be applied in a variety of interference settings, whicich we illustrate briefly. Having introduced these basic assumptions, we review the classical interference paradigms from which these ideas emerged, as well as the variety of particular conceptions of forgetting developed in the context of these procedures. Many of these ideas remain relevent today, influencing how we conceive intereference in modern terms. In the next section, we move outside of teh classical arena to review more recent phenomena that both support and challenge classical conceptions of interference. These phenomena provide compelling illustrations of the generality of interference and, consequently, of the importance of our understanding its mechanisms. We close by highlighting a recent perspective on interference that builds upon insights from modern work, while validating intuitions underlying several of the classical interference mechanisms. According to this new perspective, forgetting derives not from acquiring new memories per se, but from the impact of later retrievals of the newly learned material. After discussing findings from several paradigms that support this retrieval-based view, we illustrate how forgetting might be linked to inhibitory processes underyling selective attention.
1995
Michael C Anderson, B A Spellman (1995) On the status of inhibitory mechanisms in cognition : Memory retrieval as a model case. Psychological Review 102: 1. 68-100  
Theories of cognition frequently assume the existence of inhibitory mechanisms that deactivate mental representations. Justifying this assumption is difficult because cognitive effects thought to reflect inhibition can often be explained without recourse to inhibitory processes. This article addresses the uncertain status of cognitive inhibitory mechanisms, focusing on their function in memory retrieval. On the basis of a novel form of forgetting reported herein, it is shown that classical associative theories of interference are insufficient as accounts of forgetting and that inhibitory processes must be at work. It is argued that inhibitory processes are used to resolve computational problems of selection common to memory retrieval and selective attention and that retrieval is best regarded as conceptually focused selective attention.
1994
Michael C Anderson, Robert A Bjork, Elizabeth L Bjork (1994) Remembering can cause forgetting : Retrieval dynamics in long-term memory. Journal of Experimental Psychology : Learning, Memory, and Cognition 20: 5. 1063-1087. 
Three studies show that the retrieval process itself causes long-lasting forgetting. Ss studied 8 categories (e.g., Fruit). Half the members of half the categories were then repeatedly practiced through retrieval tests (e.g., Fruit Or). Category-cued recall of unpracticed members of practiced categories was impaired on a delayed test. Experiments 2 and 3 identified 2 significant features of this retrieval-induced forgetting: The impairment remains when output interference is controlled, suggesting a retrieval-based suppression that endures for 20 min or more, and the impairment appears restricted to high-frequency members. Low-frequency members show little impairment, even in the presence of strong, practiced competitors that might be expected to block access to those items. These findings suggest a critical role for suppression in models of retrieval inhibition and implicate the retrieval process itself in everyday forgetting.
Michael C Anderson, Robert A Bjork (1994) Mechanisms of inhibition in long-term memory : A new taxonomy In: Inhibitory Processes in Attention, Memory, and Language  Edited by:D Dagenbach, T H Carr.  265-325 San Diego, CA: Academic Press. 
Assessing whether impaired performance reflects inhibitory processes requires both a familiarity with inhibitory and noninhibitory mechanisms that might produce it, and an empirical criterion for deciding among those mechanisms. This chapter answers these demands by considering such mechanisms and by offering such a criterion. First, we construct a new taxonomy of the various noninhibitory and inhibitory models we have either encountered in the literature or generated on the basis of logical considerations. It is our hope that vivid illustrations of the many theoretical alternatives will be useful as a tool for interpreting empirical findings and will encourage cross-comparison of the reviewed models. Next, we describe a minimal criterion-cue-independent impairment-developed by Anderson and Spellman (1991a, 1991b, 1993) for establishing an effect as inhibitory. Although developed m the context of episodic memory research, the criterion of cue-independent impairment is quite general and may be adapted to most of the domains concerned with the study of inhibition. To illustrate this criterion, we describe a study by Anderson and Spellman demonstrating cueindependent forgetting. This study argues that inhibitory mechanisms produce retrieval inhibition, at least in the case of retrieval-induced forgetting. The final section advances three challenges to those interested in developing theories of the role of inhibition in long-term memory.