PUBLICATION

ABSTRACT

Huddleston, E. & Anderson, M.C. (2012). Reassessing Critiques of the Independent Probe Method for Studying Inhibition. Journal of Experimental Psychology: Learning, Memory and Cognition.

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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.

Anderson, M.C., Reinholz, J., & Kuhl, B. & Mayr, U. (2011). Intentional suppression of unwanted memories grows more difficult as we age. Psychology and Aging. 26, 397-405.

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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.

Goodmon, L., & Anderson, M.C. (2011). Semantic integration as a boundary condition on inhibitory processes in episodic retrieval. Journal of Experimental Psychology: Learning, Memory and Cognition.

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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.

Hulbert, M.C., Shivde, G.S., & Anderson, M.C. (2011). Evidence against associative blocking as a cause of cue-independent retrieval-induced forgetting. Experimental Psychology.

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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.

Anderson, M.C., & Huddleston, E. (2011). Towards a Cognitive and Neurobiological Model of Motivated Forgetting. In Belli, R. F. (Ed.), True and false recovered memories:  Toward a reconciliation of the debate. Vol. 58: Nebraska Symposium on Motivation.  New York: Springer. 

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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.

Kuhl, B., & Anderson, M.C. (2011). More is not always better: Paradoxical effects of repetition on semantic accessibility. Psychonomic Bulletin and Review.

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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.

Shivde, G.S., & Anderson, M.C. (2011). On the existence of semantic working memory: Evidence for direct semantic maintenance. Journal of Experimental Psychology: Learning, Memory and Cognition.

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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.

Anderson, M.C., & Levy, B.J. (2010). On the relation between inhibition and interference in cognition. In A. Benjamin (Ed). Successful Remembering and Successful Forgetting: Essays in Honor of Robert A. Bjork, American Psychological Association.

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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.

Anderson, M.C., & Weaver, C. (2009). Inhibitory control over action and memory. In L. Squire (Ed.). The Encyclopedia of Neuroscience. Elsevier.

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Levy, B.J., & Anderson, M.C. (2009). The control of mnemonic awareness. Encyclopedia of Consciousness. William P. Banks (Ed.). Elsevier.

 

Anderson, M.C., & Levy, B.J. (2009). Suppressing Unwanted Memories. Current Directions in Psychological Science, 18(4), 184-194.

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.

Paz-Alonso, P.M., Ghetti, S., Matlen, B.J., Anderson, M.C., & Bunge, S.A. (2009). Memory suppression is an active process that improves over childhood. Frontiers in Human Neuroscience, 3, 1-6.

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 812 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 fi rst 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 fi rst 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 fi ndings suggest that memory suppression is an active process that develops during late childhood, likely due to an age-related refi nement in the ability to engage PFC to down-regulate activity in areas involved in episodic retrieval.

Garcia-Bajos, E., Migueles, M., & Anderson, M.C. (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 lowtypicality 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.

Hulbert, J. C., & Anderson, M. C. (2008). The role of inhibition in learning. In A. S. Benjamin, S. de Belle, B. Etnyre & T. Polk (Eds.), Human Learning: Biology, Brain, and Neuroscience (pp. 7-20). North-Holland: Elsevier.

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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.

Flegal, K.E. & Anderson, M.C. (2008). Overthinking 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.

Levy, B.J. & Anderson, M.C. (2008). Individual differences in the suppression of unwanted memories: The executive deficit hypothesis. Acta Psychologica, 127, 623-635.

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.

Levy, B.J., McVeigh, N.D., Marful, A., & Anderson, M.C. (2007). Inhibiting your native language: The role of retrieval-induced forgetting during second language acquisition. Psychological Science, 18, 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, comprising a case of phonological retrieval-induced forgetting. Two studies 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 word is inhibited, as access to the concept underlying the presented objects was facilitated, not impaired. Importantly, subjects who showed the largest asymmetry between English and Spanish fluency suffered more inhibition for native language words, supporting the idea that inhibition plays a functional role in overcoming interference during the early stages of second-language acquisition.
Anderson, M.C. & Levy, B.J. (2007). Theoretical issues in inhibition: insights from research on human memory.  In D. Gorfein & C. MacLeod (Eds.) Inhibition in Cognition.

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.
Anderson, M.C. (2007). Inhibition in long-term memory.  In Y. Dudai, R. Roediger, E. Tulving, and S. Fitzpatrick (Eds.) The Science of Memory: Concepts.

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.

Anderson, M.C., & Levy, B.J. (2006). Encouraging the nascent cognitive neuroscience of repression. Behavioral and Brain Sciences, 29, 511-513.

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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.

Anderson, M.C. (2006). Repression: A cognitive neuroscience approach.  In M.Mancia (Ed.) Neuroscience and Psychoanalysis, pp. 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.
Anderson, M.C.  (2005). The role of inhibitory control in forgetting unwanted memories: A consideration of three methods. In C. MacLeod & B. Uttl (Eds.) Dynamic Cognitive Processes, pp. 159-190. Tokyo: Springer-Verlag.

When confronted with reminders to things that we would prefer 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: response override. In such situations, one must stop a strong habitual response 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 neuroimaging 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 prefrontal 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.

Johnson, S.K., & Anderson, M.C. (2004). The role of inhibitory control in forgetting semantic knowledge. Psychological Science, 15, 448-453.

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, subjetcs used general knowledge to generate 0 (baseline), 1, 4, or 8 different items of semantic knowledge. Afterwards, we determined through an apparently unrelated free-association test whether a critical non-practiced 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.

Anderson, M.C., Ochsner, K.N., Kuhl, B., Cooper, J., Robertson, E., Gabrieli, S.W., Glover, G.H., Gabrieli, J.D.E. (2004). Neural systems underlying the suppression of unwanted memories. Science, 303, 232-235.

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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.

Anderson, M.C. (2003). Rethinking interference theory: Executive control and the mechanisms of forgetting. Journal of Memory and Language, 49, 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.

Anderson, M.C., & Levy, B.J. (2002). Repression can (and should) be studied empirically: Reply from Anderson and Levy. Trends in Cognitive Sciences, 6, 502-503.

 

Levy, B.J., & Anderson, M.C. (2002). Inhibitory processes and the control of memory retrieval. Trends in Cognitive Sciences, 6, 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.

Anderson, M.C. & Green, C. (2001). Suppressing unwanted memories by executive control. Nature, 410, 131-134.

Behavioral and neurological 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. In this study, the authors show that these mechanisms can be recruited to prevent unwanted declarative memories from entering awareness, and that this cognitive act had enduring consequences for the rejected memories. 32 normal college students participated in each experiment, except Exp 4, in which there were 16. When people encountered cues that reminded them of an unwanted memory and consistently tried to prevent awareness of it, the later recall of the rejected memory became more difficult. The forgetting increased with the number of times the memory was avoided, resisted incentives for accurate recall and was caused by processes that suppressed the memory itself. These results show that executive control processes not uniquely tied to trauma may provide a viable model for repression.

Shivde, G., & Anderson, M.C. (2001). The role of inhibition in meaning selection: Insights from retrieval-induced forgetting. D. Gorfein (Ed), On the Consequences of Meaning Selection: Perspectives on Resolving Lexical Ambiguity, pp. 175-190. Washington, D.C.: 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.

Anderson, M.C., & Bell, T. (2001). Forgetting our facts: The role of inhibitory processes in the loss of propositional knowledge. Journal of Experimental Psychology: General, 130, 544-570.

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.

Anderson, M.C. (2001) Active forgetting: Evidence for functional inhibition as a source of memory failure. Journal of Aggression, Maltreatment & Trauma, 4, 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.

Anderson, M.C., Bjork, E.L., & Bjork, R.A. (2000). Retrieval-induced forgetting: Evidence for a recall-specific mechanism. Psychonomic Bulletin and Review, 7, 522-530.

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.

Anderson, M.C., Green, C., & McCulloch, K.C. (2000). Similarity and inhibition in long-term memory: Evidence for a two-factor model. Journal of Experimental Psychology: Learning, Memory and Cognition, 26, 1141-1159.

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.

Anderson, M.C., & McCulloch, K.C. (1999). Integration as a general boundary condition on retrieval-induced forgetting. Journal of Experimental Psychology: Learning, Memory, and Cognition, 25, 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.

Bjork, E.L., Bjork, R.A., & Anderson, M.C. (1998). Varieties of goal-directed forgetting. J.M. Golding & C.M. MacLeod (Eds.), Intentional forgetting: Interdisciplinary approaches, pp. 103-137.

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.

Anderson, M.C. & Neely, J.H. (1996). Interference and inhibition in memory retrieval. E.L. Bjork & R.A. Bjork (Eds.), Memory. Handbook of Perception and Cognition (2nd ed.), pp. 237-313. 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.

Anderson, M.C., & Spellman, B.A. (1995). On the status of inhibitory mechanisms in cognition: Memory retrieval as a model case. Psychological Review, 102, 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.

Anderson, M.C., Bjork, R.A., & Bjork, E.L. (1994). Remembering can cause forgetting: Retrieval dynamics in long-term memory. Journal of Experimental Psychology: Learning, Memory and Cognition, 20, 1063-1087.

Three studies with 148 university students 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. Exps 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. Findings suggest a critical role for suppression in models of retrieval inhibition and implicate the retrieval process itself in everyday forgetting.

Anderson, M.C., & Bjork, R.A. (1994). Mechanisms of inhibition in long-term memory: A new taxonomy. D. Dagenbach & T. Carr (Eds.), Inhibitory Processes in Attention, Memory and Language, pp. 265-326. 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.