recovered memories of traumaphenomenology and cognitive mechanisms

Clinical Psychology Review, Vol. 18, No. 8, pp. 949–970, 1998Copyright © 1998 Elsevier Science LtdPrinted in the USA. All rights reserved

0272-7358/98/$–see front matter

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949

RECOVERED MEMORIES OF TRAUMA: PHENOMENOLOGY AND

COGNITIVE MECHANISMS

Chris R. Brewin and Bernice Andrews

Royal Holloway, University of London

ABSTRACT.

We outline four current explanations for the reported forgetting of traumaticevents, namely repression, dissociation, ordinary forgetting, and false memory. We then reviewthe clinical and survey evidence on recovered memories, and consider experimental evidence thata variety of inhibitory processes are involved in everyday cognitive activity including forgetting.The data currently available do not allow any of the four explanations to be rejected, andstrongly support the likelihood that some recovered memories correspond to actual experiences. Wepropose replacing the terms repression and dissociation as explanations of forgetting with an ac-count based on cognitive science. © 1998 Elsevier Science Ltd

IN THE LAST few years doubt has been repeatedly cast over whether individuals canforget significant traumatic experiences and then recover essentially accurate memo-ries of these events. The strongest doubts have been expressed over recovered memo-ries of repeated childhood sexual abuse (e.g., Kihlstrom, 1995; Loftus, 1993; Loftus &Ketcham, 1994; Ofshe & Watters, 1994; Pendergrast, 1995). In response, other au-thors have documented cases of recovered memories, or have explored the scientificbasis for theorising that recovered memories of traumatic events are or are not likelyto be valid (Conway, 1997; Freyd, 1996; Lindsay & Read, 1994, 1995; K. S. Pope &Brown, 1996; Read & Lindsay, 1997; Schooler, 1994; Terr, 1994). In this article we de-scribe competing hypothetical processes which have been put forward to explain thereal or apparent recovery of traumatic memories, and review what is now a substantialbody of evidence concerning the ecology and phenomenology of recovered memo-ries. We then review experimental studies of inhibitory processes in attention andmemory, and work on individual differences in forgetting, which we believe is rele-vant to explaining genuine memory recovery. Finally we put forward our own theoret-

Correspondence should be addressed to Chris R. Brewin, Cognition Emotion and TraumaGroup, Department of Psychology, Royal Holloway, University of London, Egham, SurreyTW20 0EX, UK.

950 C. R. Brewin and B. Andrews

ical suggestions for integrating traditional ideas about psychological defences withlaboratory evidence on cognitive processes.

The basic phenomenon of recovered memory for trauma has been described else-where (e.g., Alpert, Brown, & Courtois, 1996; Freyd, 1996; Lindsay & Read, 1994,1995), and will not be reviewed in detail. To summarize, however, clinicians workingwith survivors of traumatic experiences have frequently noted the existence of psy-chogenic amnesia and the recovery of additional memories during clinical sessions,although the proportion of cases in which there is amnesia for significant parts of atraumatic event is not known. Recently, surveys of women in therapy for the effects ofchildhood sexual abuse have found that a substantial proportion, varying from 20–60%, report periods of forgetting some or all of the abuse (Briere & Conte, 1993;Herman & Schatzow, 1987; Loftus, Polonsky, & Fullilove, 1994). Surveys of traumasurvivors among the general population, psychologists and students (Elliott & Briere,1995; Feldman-Summers & Pope, 1994; Melchert, 1996; van der Kolk & Fisler, 1995)also describe similar periods of forgetting in a comparable proportion of respon-dents. Follow-up studies of children with documented abuse have found that abuse issometimes not reported when the children are re-interviewed some years later (Bag-ley, 1995; Williams, 1994).

Some authors have noted that amnesia may extend beyond the traumatic event,and that individuals may describe partial or complete memory loss for periods ofmonths or years while they were growing up (e.g., Bagley, 1995; Harvey & Herman,1994). Individuals also differ in the extent to which they report awareness of the exist-ence of a memory, as opposed to the content of a memory, and in the extent to whichthey report actively trying to keep memories out of consciousness. Thus in Melchert’s(1996) questionnaire survey of college students, a majority of the 41 who reportedthey had previously forgotten early physical, emotional or sexual abuse also reportedthey had consciously attempted to avoid memories, whereas a minority reported be-ing previously completely unaware of the memories. It is worth noting that Schooler,Bendiksen, and Ambadar (1997) reported the case of an individual who, althoughshe believed she had not recalled a traumatic event for many years, had fairly recentlyhad a conversation with her husband about it. This suggests that it is possible to for-get about remembering, as well as to forget the original trauma.

CURRENT EXPLANATIONS OF OBSERVED FORGETTING

To date such observations have been explained in four main ways, either as examplesof the psychological defences of repression or dissociation, or as ordinary forgetting,or as false memories.

Repression

In discussing repression, it is necessary to begin with a description of the original for-mulation of the concept and of its relation to other clinical phenomena involvingpsychogenic forgetting. In 1895, Breuer and Freud (1895/1974) noted “it was a ques-tion of things which the patient wished to forget, and therefore intentionally re-pressed from his conscious thought and inhibited and suppressed” (p. 61). There aremany indications that Freud was uncertain about whether repression should bethought of as a process that is unconscious from the outset (“primary repression”), to

Memories of Trauma 951

be contrasted with a conscious act of suppression, or whether repression should beconsidered as an unconscious process that only develops following a period of delib-erate suppression (“repression proper” or “after-expulsion”). This uncertainty has re-mained with the field ever since (Erdelyi, 1990).

Theoretically, however, the two forms of repression have very different implications.Primary repression implies the need for preconscious or unconscious mechanismsthat block any conscious processing being accorded to the traumatic scene. Thus for-getting is seen as arising from a failure to encode information. After-expulsion oper-ates on material that has already received fairly extensive conscious processing. Thefocus is therefore on a failure of storage or retrieval rather than of encoding. Manyexamples of this process may be found in textbooks on cognitive psychology underthe heading of “motivated forgetting” (Freyd, 1996).

Dissociation

The other major defence mechanism associated with forgetting is dissociation, the fo-cus of theorizing by Janet in the last century (Janet, 1889). As noted by Cardeña(1994), this term “simply means that two or more mental processes or contents arenot associated or integrated. It is usually assumed that these dissociated elementswould be integrated in conscious awareness, memory, or identity” (p. 15). A dissocia-tive state is an altered state of consciousness in which ordinary perceptual, cognitiveor motor functioning is impaired. For example, there appears to be a spectrum ofdissociative states involving greater or lesser degrees of awareness of the current envi-ronment. Thus, in therapy sessions, dissociative states may range from a reduced abil-ity to hear or see the therapist, a transient sense of depersonalisation or derealisation,or an out-of-body experience, to a complete loss of awareness of time and space.Sometimes these states are accompanied by

flashbacks

, a term we use to include aspectrum of involuntary mental intrusions, ranging from fragmentary sensorimotorexperiences to the sensation of vividly reliving a whole past experience in the present.Other dissociative states involve what appears to be a separate personality. Althoughdissociation does not invariably involve amnesia, lack of memory for events experi-enced in different states is commonly reported.

Several trauma theorists (e.g., Alpert et al., 1996; Briere, 1992; van der Kolk &Fisler, 1995) have recently proposed that peri-traumatic dissociation (i.e., dissociationthat occurs during the traumatic experience) is a defence that prevents the individ-ual from experiencing the full impact of what is happening. Patients describe beingtemporarily detached from the situation, sometimes observing what is occurring butwithout any pain or distress. These reactions have been invoked to explain how peo-ple exposed to repeated traumas may nevertheless be able to forget them (Herman,1992a; Terr, 1991). Retrieval of a dissociated memory reflects the fact that little, ifany, ordinary conscious processing took place at encoding. Thus, as argued by vander Kolk and Fisler (1995), these memories are characterised by vivid and intensesensory and perceptual elements, by fragmentation, and by a stereotyped repetitivequality that endures over multiple retrievals.

Ordinary Forgetting

In contrast, Loftus and her colleagues (Loftus, Garry, & Feldman, 1994) suggestedthat the forgetting of trauma was no different from the forgetting of everyday events,


and that no special mechanisms were required to explain it. Forgetting could be ac-counted for by the normal processes of interference by new events and by the gradualdecay of unrehearsed memory traces, resulting in a progressive decrease in the prob-ability of the traumatic memory being retrieved.

This explanation is particularly relevant to single traumatic episodes, but has moredifficulty in accounting for the forgetting of repeated traumatic episodes. As noted byLindsay and Read (1994), standard cognitive theory holds that memory for a singleevent is likely to be poorer than memory for a series of similar events. Thus, from thisperspective, the apparent recovery of repeated trauma is likely to be of questionablevalidity. The “ordinary forgetting” hypothesis also focuses on forgetting as primarily afunction of interference and decay processes, to the exclusion of inhibitory mecha-nisms.

False Memories

A fourth explanation for the apparent “forgetting” and then recall of childhoodtrauma has been put forward by the False Memory Syndrome Foundation (FMSF) inthe U.S. and by its counterparts in other countries, such as the British False MemorySociety (BFMS). Loftus (1993) suggested that at least some of the memories of childsexual abuse (CSA) recovered in therapy may not be veridical, but may be false mem-ories “implanted” by therapists who have prematurely decided that the patient is anabuse victim and who use inappropriate therapeutic techniques to persuade the cli-ent to recover corresponding “memories.” The false memory societies have claimedthat there are many cases known to them in which previously happy families have beendisrupted by accusations of abuse that were only triggered by an adult child enteringtherapy. Several authors (e.g., Belli & Loftus, 1994; Destun & Kuiper, 1996; Hyman &Loftus, 1998; Lindsay & Read, 1994, 1995; Loftus, 1993) have reviewed relevant litera-ture on autobiographical memory, eyewitness testimony, reality monitoring, suggest-ibility, and studies concerning the fallibility and malleability of memory, concludingthat the creation of false memories within therapy is a possibility that must be takenseriously. The likelihood of suggestive influences leading to memory errors is in-creased by the perceived authority and trustworthiness of the source of suggestions,repetition of suggestions, their plausibility and imagibility, and lowering of memory-monitoring response criteria (Lindsay & Read, 1995). As noted by these authors, suchfeatures may characterise a type of therapy that they term “long-term, multifaceted,suggestive memory work,” and they review a considerable amount of evidence sup-porting the view that this type of therapy could indeed give rise to false memories.

Various members of the scientific advisory boards of the false memory societieshave warned about the likely unreliability of “memories” recovered in this way (Kihl-strom, 1995; Merskey, 1995; H. G. Pope & Hudson, 1995; Wakefield & Underwager,1992). As K. S. Pope (1996) has recently argued, however, the current evidential basefor a “false memory syndrome” is weak and depends on a number of crucial but em-pirically untested assumptions. Thus, it also at present has the status of a hypotheticalmechanism that may explain observations of apparent forgetting.

Distinguishing Between Explanations

Which of these four explanations (repression, dissociation, ordinary forgetting, falsememory) is more likely to be correct? Are all correct? Can any be ruled out? A major


consideration is plausibility. Numerous members of the scientific advisory boards ofthe false memory societies have argued that it is implausible that many of these mem-ories of abuse apparently recovered after long periods of time correspond to actualevents because: (a) the content is either stereotypical, conforming to therapists’ pre-conceptions about child sexual abuse as a ubiquitous cause of psychological disorder,or highly unusual, for example of Satanic rituals with human sacrifices; (b) the age atwhich the events are supposed to have occurred may precede the development of ex-plicit event memory; (c) there is typically no independent corroboration of theevents; (d) therapists may hold inaccurate beliefs about the accuracy of memory andmay employ procedures such as hypnosis or guided fantasy that increase the risk ofimaginary scenes and images being interpreted as actual events; and (e) the condi-tions under which recall occurs, for example memories being recovered from totalamnesia within therapy sessions, may be stereotyped, again reflecting therapists’ pre-conceptions.

Equally, more plausibility would accrue to the view that recovered memories oftencorrespond to actual events if it could be shown: (a) the content of most recoveredmemories concerns a variety of events known to occur with reasonable frequency,and is not limited to child sexual abuse; (b) the age at which the events are said tohave occurred extends beyond the period of infant amnesia; (c) corroboration oc-curs with reasonable frequency given the nature of the alleged incidents; (d) well-trained therapists not using inappropriate techniques also report clients recoveringmemories; and (e) the context of recall is not limited to the therapist’s office anddoes not always involve total amnesia but occurs in a variety of ways and under a vari-ety of conditions.

Given that the recovery of essentially accurate memories of trauma after a periodof forgetting is agreed to occur in some cases, the plausibility of competing accountsof forgetting depends in part on whether: (a) clients report active attempts to forgetmemories or banish them from consciousness, and the strategies they use to do this;(b) the memories recalled possess the hallmarks of disrupted encoding, such as frag-mentation, intense sensory and perceptual features, and the experience of relivingthe event in the present; (c) evidence for inhibitory processes can be found in every-day cognitive tasks; (d) ordinary individuals display a selective problem in processingnegative memories. In the next two sections of this article, we consider the clinicaland experimental evidence relevant to these issues.

CLINICAL AND SURVEY EVIDENCE

Content of Recovered Memories

Several surveys have now been published that indicate the kinds of conditions sur-rounding memory recovery and the content of the memories. Morton et al. (1995)reviewed the frequency with which, according to records kept by the false memory so-cieties, recovered memories involved reports of Satanic or ritual abuse (SRA). TheAmerican data were abstracted from a report produced in Summer 1993 by the direc-tor of the False Memory Syndrome Foundation. This indicated that 11% of callersmentioned such abuse when asked an open-ended question, and 18% when asked aclosed question. The British data were derived from inspection of around 200records of telephone calls received by the BFMS and made available to Morton et al.by its director. In this sample SRA was explicitly mentioned in 6% of the callers’


records. A subsequent survey of around 400 BFMS members (Gudjonsson, 1997) ob-tained a 70% response rate, with approximately 70% of responders agreeing that re-covered memories were involved in the accusations, 20% not being sure or not an-swering the question, and 10% denying that recovered memories were involved.Thus clear indications about the possible involvement of recovered memories wereonly obtained from about half the membership. Gudjonsson reported that 8% of re-spondents agreed that accusations involved SRA when asked a closed question about it.

Andrews et al. (1995) sent questionnaires to chartered psychologists in the UK andobtained a response rate of 27%. Almost half of the 810 with relevant caseloads whoreplied said they had at some time in the past had a patient retrieve a memory fromtotal amnesia while in therapy with them. A subset of this sample was followed up in atelephone survey by Andrews et al. (1997a), and were asked detailed questions aboutup to three recent clients who had had recovered memories. Just 5% of the memoriesinvolved ritual cult abuse, and one memory involved an alien abduction.

The Andrews et al. (1995) survey also inquired about memories for non-CSAevents. Over a quarter of the respondents reported having clients recovering suchmemories in the past year. Because the vast majority had at least one client reportingCSA, it was possible that these memories were exclusively related to that experience,and arose only in the course of recovering CSA memories. To control for this possi-bility, respondents who had no CSA clients were distinguished from the rest. The pro-portions with clients with non-CSA recovered memories were fairly similar in the twogroups—29% with CSA clients and 21% with no such clients.

In the follow-up survey (Andrews et al., 1997a), therapists were asked about thecontent of these non-CSA memories. The most frequent categories involved otherchild maltreatment, traumatic medical procedures, and witnessing violence or death.Other studies have similarly reported the existence of non-CSA recovered memories(Feldman-Summers & Pope, 1994; Melchert, 1996; Schooler et al., 1997).

Age of Memory

There is currently some dispute about the earliest age at which episodic memories ofsignificant childhood events may be retained and later retrieved. Some reports putthis as early as the third year of life (Howes, Siegel, & Brown, 1993; Usher & Neisser,1993). In any event, there is agreement on the paucity of evidence for later retrievalof verbal memories from the first 2 years of life, and on the rarity of memories fromthe third year of life. It is also important to distinguish between memories for singleevents falling within the period of infant amnesia, and memories for a series of eventsthat commenced within the period of infant amnesia but continued for several years.Whereas the former are highly implausible, the latter may be more readily explainedas involving guesses about the age of onset without necessarily casting doubt on thevalidity of the pattern of events described.

Morton et al. (1995) reported that, according to the American FMSF data, 26% ofallegations involved abuse that had begun when the child was aged 0–2. However,only 6% of allegations involved abuse that ended before age 5. In the British BFMSrecords reviewed by Morton et al., 4% of allegations involved abuse that ended be-fore age 5. In Gudjonsson’s (1997) BFMS survey, 7% of allegations involved abuseending before age 5, this figure reducing to 3% if missing cases are included in thedenominator (Andrews, 1997). Andrews et al.’s (1997a) telephone survey of British


therapists found that 2% of the events in their clients’ recovered memories were re-ported to have begun and ended before age 3.

Corroboration

In general, memories of childhood appear to be reasonably accurate and there is noevidence that they are biased by mood states such as depression (Brewin, Andrews, &Gotlib, 1993). Although it is not clear a priori why recovered memories should be lessaccurate than memories an individual has always been aware of, some authors havedemanded stringent evidence of the authenticity of a memory before they are willingto concede that it has been recovered after a period of amnesia. For example, despitethe problems arising from the relatively recent appreciation of the extent and impor-tance of child sexual abuse, and the fact that such events usually occur in secret,H. G. Pope and Hudson (1995) argued that studies of abuse survivors provided insuf-ficient evidence to support the concept of the recovery of forgotten memories oftrauma.

In fact there are several reports of individual cases where documentary corrobora-tion of forgotten trauma has been reported (Schooler, 1994; Schooler et al., 1997).Such evidence is also available from Williams’s (1994) follow-up study of women withdocumented histories of CSA. In her sample, approximately one in six of the womenwho recalled the abuse at interview said that there had been a period when they hadcompletely forgotten the abuse. When current accounts of the abuse and the originalrecords were compared, Williams (1995) reported that the accounts of women withrecovered memories were just as accurate as those of women who had always remem-bered the abuse.

Feldman-Summers and Pope (1994) asked their respondents for any corroborativeevidence for recovered memories of abuse. Forty-seven percent reported some cor-roboration, for example the abuser acknowledged some or all of the rememberedabuse, someone who knew about the abuse told the respondent, or someone else re-ported abuse by the same perpetrator. Gudjonsson (1997) also noted that 8 respon-dents in his survey of BFMS members admitted there was some truth in the allega-tions.

Finally, Andrews et al. (1997a) enquired from the therapists in their survey aboutcorroborative evidence. Overall, in 41% of client cases it was reported that the clienthad found some sort of corroboration, and in 5% (11 cases) the respondent actuallysaw the evidence.

Therapists and Their Practices

At least three studies have provided confirmation that some therapists hold beliefsthat run contrary to what we know about memory. One survey of around 860 hypno-therapists and family therapists attending conferences and workshops in the UnitedStates was mainly concerned with beliefs about hypnosis (Yapko, 1994). The other in-vestigated 145 U.S. and 57 UK psychologists’ practices and experiences as well asmore general beliefs concerning memory recovery of sexual abuse in childhood(Poole, Lindsay, Memon, & Bull, 1995). Both surveys also found a high proportion ofrespondents endorsing the belief that recovered memories can be false. In Poole etal.’s study, the British respondents (who were all chartered clinical psychologists)were less likely than their U.S. counterparts to use memory recovery techniques such


as hypnosis and age regression, although both groups had similarly high rates of re-spondents reporting memory recovery in at least some clients.

The majority of the respondents in the Andrews et al. (1995) survey believed thatfalse memories were possible, although the proportion with this belief (67%) wassmaller than in the other two surveys asking this question (91%, Poole et al., 1995;79%, Yapko, 1994). Twenty percent of those who had experienced recovered memo-ries in their own practice thought they had also encountered examples of false mem-ories. The majority of respondents also believed that recovered memories were some-times or usually accurate (although only a small minority believed they would alwaysbe so)—a question not asked in the other surveys. Use of hypnotic regression was re-ported by 10% of respondents, but was more common in Poole et al.’s survey.

In further detailed questioning, Andrews et al. (1997a, 1997b) distinguished be-tween techniques used specifically to aid recall as opposed to more general therapeu-tic purposes. In 21% of their client cases techniques to aid recall were used prior tothe recovery of the first memory. However, use of techniques to aid recall prior to thefirst memory recovery was not associated with faster memory recovery, and thesecases were just as likely to be accompanied by reports of corroborative evidence ascases where no techniques were employed.

Conditions of Recall

A central issue is whether recall occurs exclusively during therapy sessions, or afterthe onset of therapy, as opposed to before therapy. Feldman-Summers and Pope(1994) found that although over half of memories were recovered in the context oftherapy, 44% of their respondents stated that recovery had been triggered exclusivelyin other contexts. Andrews et al. (1995) reported that a common context in whichCSA memories were recovered was prior to any therapy, with nearly a third of respon-dents reporting that clients had recovered memories in this context. Just under aquarter had clients recovering CSA memories in therapy with them, and around onein five in therapy with someone else.

Of equal importance is the way in which memories are recovered. It is sometimesassumed that memories are invariably recovered from total amnesia, thus adding totheir implausibility. In fact this does not seem to be the case. For example, Loftus etal. (1994) distinguished between recall from total and partial amnesia, finding theformer somewhat more common than the latter in their sample. Similarly, Harveyand Herman (1994) described composite clinical cases illustrating partial amnesia, inwhich some knowledge of abuse was retained although there was forgetting of manysalient facts and episodes, and profound amnesia, in which the autobiographical factof abuse was forgotten along with the specific episodic memories. Harvey and Her-man emphasized the complexity of traumatic forgetting and the fact that recall israrely an all-or-none phenomenon. In line with these observations, both Andrews etal. (1997b) and Gold, Hughes, and Hohnecker (1994) reported different degrees offorgetting, ranging from total amnesia, through a vague sense or suspicion, to varyingamounts of partial forgetting.

Attempts to Forget

A small-scale survey by Hunter (1997) of 16 child abuse survivors revealed numerousreports of dissociative strategies which took three forms. One was an out-of-body ex-


perience (3 respondents), in which during the assaults the respondent experiencedthem as happening to a separate corporeal entity, either her or someone who lookedlike her. This did not necessarily reflect a deliberate coping strategy. The secondform was a conscious attempt to “blank out” or “distance” memories of the assaultsduring or after they had happened (3 respondents). The third strategy involved de-liberately creating an imaginary world to which the respondent could escape andwhere they would be safe, either during or after the abuse (2 respondents).

Attempts to forget are also characteristic of the vast majority of trauma survivorswho similarly report in detail the strategies they use to banish upsetting thoughts andimages from their minds (Briere, 1992; Herman, 1992b). Successful behaviouraltreatment of posttraumatic stress disorder (PTSD) frequently involves countermand-ing these instructions and having clients choose to remember in detail all aspects ofthe traumatic experience (e.g., Rothbaum & Foa, 1996). It is also now recognised bycognitive-behaviour therapists that the effects of exposure to a feared stimulus maybe blocked by distraction or cognitive avoidance (e.g., Rachman, 1980). Influentialcognitive-behavioural theories now explicitly contain the idea that mental activity canbe used to block feared images or thoughts, and considerable efforts are now madeto diagnose and prevent cognitive avoidance at an early stage.

Qualities of Recovered Traumatic Memories

Andrews et al. (1997b) collected detailed information about the qualities of the re-covered memories in their 236 client cases. The recovered memories their respon-dents described revealed many similarities with descriptions of “flashbulb memories”and with the memories of patients diagnosed with PTSD (Brewin, Dalgleish, & Jo-seph, 1996; Foa, Molnar, & Cashman, 1995; Terr, 1991; van der Kolk & Fisler, 1995).The memories were overwhelmingly recovered in the form of specific episodes ratherthan autobiographical facts, and it was usual to recall a number of memories of differ-ent events. Fear and distress were the most common accompanying emotions, andmost memories, but not all, were detailed and involved what appeared to be a degreeof reliving of the original experience. There was more heterogeneity, however, interms of whether memories were recovered in parts or fragments, or whether theywere recovered as whole episodes. The majority of memories appeared to be recov-ered at least initially in the form of fragments.

Summary

From the clinical and survey data reviewed it is apparent that there are indicationsthat at least some recovered memories may not correspond to actual events. A smallminority of memories contain unusual content or refer to events that occurred at anage preceding the development of verbal memories. Some memories occur withintherapy following the use of a specific technique to aid recall and cannot be corrobo-rated, and some practitioners appear to have important misconceptions about thenature of memory. At the same time the data from these surveys suggest that many re-covered memories are not amenable to this kind of explanation. Memory recoveryappears to be a remarkably robust phenomenon, occurring in and out of therapy andinvolving a wide variety of different types of event. Many well-trained practitionershave encountered the phenomenon, often without using techniques to aid recall.Studies of poorly trained practitioners might, however, reveal a different pattern.


Of particular value is the evidence that memory recovery may take several forms.Amnesia may be partial or profound, and individuals can often give accounts of delib-erate strategies they use to banish distressing memories from consciousness. Recov-ered memories may be fragmented, emotion-laden, and similar to the intrusive mem-ories of the PTSD patient, or (less often) they may more closely resemble ordinaryautobiographical memories. These observations suggest that several different kindsof underlying cognitive processes are likely to be necessary to explain such diversephenomena. In search of such processes we now turn to the experimental literature.

EXPERIMENTAL EVIDENCE

Inhibitory Processes in Everyday Cognition

Inhibition in the cognitive system has been discussed by numerous researchers whoinvestigate the topics of attention and memory. In a manner analogous to neuronalinteractions, there is evidence for lateral inhibition of related constructs in memory.Lateral inhibition enhances the processing of a target item or set of items by decreas-ing the processing afforded to related but irrelevant items which might potentially in-terfere with the target. One example is retrieval-induced forgetting (Anderson,Bjork, & Bjork, 1994). In the study phase, subjects study several categories, each witha set of examples (e.g., Animal-Horse, Animal-Tiger). In the second phase subjectspractice retrieval of half the items from the studied categories by completing cate-gory-plus-exemplar stem cue tests (e.g., Animal-Ho______?). The remaining itemsare not retrieved. Following a retention interval, there is an unexpected recall test inwhich subjects are cued with the category name (Animal) and asked to remember asmany exemplars as possible. Under these conditions subjects recall more of the prac-tised items but at the expense of unpractised items from the same categories—recallof these unpractised items is impaired relative to recall of items from baseline catego-ries in which no items were practised. Subsequent studies using this paradigm havesuggested that there are active inhibitory processes serving to reduce the level of acti-vation of unpractised items from practised categories, and hence enhancing retrievalof the practised (target) items (Anderson & Spellman, 1995).

Likewise, Simpson and Kang (1994) investigated the naming of words that were re-lated to alternative meanings of a homograph prime. On each of two successive trialssubjects were presented with a prime word, followed by a target word that they had toname as quickly as possible. When subjects were first exposed to a prime-target pairexemplifying one meaning of the homograph (e.g., bank-stream), they were subse-quently much slower to name a target related to the other meaning of the homo-graph (e.g., bank-money). The previous context was effective in reducing the accessi-bility of words related to one meaning of the homograph, even when this was themost common meaning. Simpson and Kang concluded from the results of severalstudies that, on stimulus presentation, all competing meanings are initially activated,but that this is followed by the suppression of unwanted or irrelevant meanings. Foranother example of work implicating the lateral inhibition of related meanings, seeDagenbach, Carr, and Barnhart (1990) and Carr and Dagenbach (1990).

However, inhibitory effects are not limited to stimuli that are already associated byvirtue of prior learning. In their analysis of the neural substrate of attentional pro-cesses, Posner and Peterson (1990) distinguished between a posterior system that ori-ents to objects in the external world and generates perceptual awareness, and an an-


terior system that orients to the meaning of internal stimuli such as percepts andguides selection for action. Rafal and Henik (1994) suggested that the anterior atten-tional system is able to maximise the efficiency of goal-directed behaviour by exercis-ing inhibitory control over automatic processes.

For example, Tzelgov, Henik, and Berger (1992) investigated the effect of expecta-tions on the Stroop test, in which subjects have to name the color in which a word isprinted and ignore the word itself. Generally, color naming is speeded when thecolor and the word are congruent (e.g., red-red) and slowed when the color and theword are incongruent (e.g., red-green), relative to neutral trials in which the colorand the word are unrelated (e.g., red-sock). This is usually interpreted as due to auto-maticity effects in word reading. However, under conditions in which subjects are ex-pecting a high proportion of incongruent color-word pairs such as red-green, theyappear able to inhibit word reading and increase the speed of color naming, relativeto a control condition in which incongruent color-word pairs are unexpected.

These examples of selective attention are closely related to the phenomenon of di-rected forgetting. This paradigm involves comparing the recall of stimuli that sub-jects are instructed either to remember or to forget. There are several methods usedto designate some material as to-be-forgotten (TBF) and some material as to-be-remembered (TBR). Midway through presentation of a word list, for example, sub-jects may be instructed to forget the first half of the list and remember the secondhalf of the list. This is termed a

global instruction to forget

, because a whole set of itemsoccurring together are to be forgotten. Another method involves designating stimulias TBR or TBF by instructions given after the presentation of the entire list (e.g., for-get the animal names). This is termed a

specific instruction to forget

, because only a sub-set of the item pool is to be forgotten. In a surprise recall test of all the items, includ-ing those subjects were told to forget, subjects given global or specific instructions toforget recall fewer stimuli in the TBF set than in the TBR set. In a recognition test,however, the difference between TBF and TBR items disappears.

Geiselman, Bjork, and Fishman (1983) conducted an ingenious experiment dem-onstrating that the directed forgetting effect is not due to subjects rehearsing theTBR items more than the TBF items, and hypothesized that a cue or instruction toforget inhibits access to the TBF items. Because recognition performance was unim-paired, they concluded that the inhibition induced via the

forget

cue took the form ofretrieval inhibition. That is, the TBF items are adequately encoded in memory butare actively excluded from entering consciousness.

What relevance do these paradigms, largely based on responses to verbal stimuli,have to clinical accounts of repression? The first thing to note is the close parallels be-tween the organisation of semantic memory and theories of self-representation. Ac-cording to Markus and Sentis (1982), Kihlstrom and Cantor (1984), and others, infor-mation in memory about the self is organised, similarly to other kinds of information,as a set of related but context-specific knowledge structures. Overlapping representa-tions preserve some consistent features of the self but also contain information relat-ing to the self at different ages and in the performance of different roles. Other as-pects of self-knowledge represented in memory include “ought” or “ideal” selves (e.g.,Strauman & Higgins, 1988), and perhaps an “undesired self” (Ogilvie, 1987).

In many respects, therefore, self-knowledge may be thought of as a particularlycomplex area of semantic memory, but one that is organised along similar principles,possibly utilising a hierarchical system of constructs and categories. What aspects ofself-knowledge are currently available to a “working self-concept” will depend on sim-


ilar factors to those that determine the content of “working memory,” such as con-text, current levels of activation, chronic accessibility, and mood. Real life situationsmay need to be disambiguated by accessing the relevant self-representation in just thesame way that homographs have to be related to the most appropriate alternativemeaning. What is perhaps unique about the self is the potential for inconsistency andhence competition among alternative self-representations, suggesting a potential rolefor automatic mechanisms such as lateral inhibition.

The role of active attentional facilitation and inhibition is even more clearly seenin individuals’ attempts at self-regulation, particularly in mood repair processes. Forexample, Power and Brewin (1990) presented ordinary subjects with primes consist-ing of positive and negative life events. Following each prime, subjects were shown apositive or negative adjective and had to say whether or not they believed the adjec-tive described them. Whereas it would ordinarily be expected that presentation of anegative prime would lead to subjects endorsing negative adjectives as true of themmore quickly, they in fact took more time, not less time, to endorse negative adjec-tives as being self-descriptive. Power and Brewin interpreted this as evidence for aninhibitory process that decreased the accessibility of negative self-representations inorder to prevent the induction of a negative mood state.

Psychiatric disorders such as depression, it has been argued, are characterised bythe breakdown of these inhibitory processes. Negative information about the self, inthe form of automatic thoughts and autobiographical memories, intrude into con-sciousness at very high frequencies. Both depression (Brewin, Hunter, Carroll, &Tata, 1996; Kuyken & Brewin, 1994), and PTSD (Brewin, Dalgleish et al., 1996) aretypified by persistent attempts on the part of patients to exclude these memoriesfrom consciousness and to reduce the probability of them being reaccessed. As wellas the obvious parallel with attentional suppression, the high frequency of instruc-tions to forget upsetting experiences, whether self-generated or provided by others,increases the similarity with directed forgetting experiments.

Individual Differences in Forgetting

Experimental evidence for inhibitory processes has so far suggested that they consti-tute a ubiquitous element of cognitive processing. As such, therefore, they are unableto explain why some people may be able to forget traumas whereas others always re-member them. It would clearly be of interest to identify a group of people who ap-pear to be particularly good at forgetting negative experiences. Such a group has infact been identified—they are individuals with a repressive coping style.

Weinberger, Schwartz, and Davidson (1979) defined repressors as individuals whoscore low on a measure of trait anxiety but high on a measure of defensiveness suchas the Marlowe-Crowne Social Desirability Scale (Crowne & Marlowe, 1964). Wein-berger et al. proposed a fourfold classification of individuals differentiated in termsof their coping styles: low anxious (low anxiety-low defensiveness), repressor (lowanxiety-high defensiveness), high anxious (high anxiety-low defensiveness), and de-fensive high anxious (high anxiety-high defensiveness). A series of studies with fe-male undergraduate students has shown that repressors have limited access to nega-tive autobiographical memories. For example, Davis and Schwartz (1987) found thatin a free recall task repressors recalled significantly fewer negative memories fromchildhood than low anxious or high anxious subjects, and that their age at the time offirst negative memory recalled was substantially older.


However, despite plausible prima facie grounds for labeling them as possessing arepressive coping style, until recently no direct evidence has been produced that theyin fact have had disturbing or unpleasant experiences in childhood. The possibilityhad not been ruled out that phenomena such as longer latencies to retrieve negativememories might in fact indicate a childhood that was happier than usual, and thusnot constitute evidence for repression. Myers and Brewin (1994) therefore used asemistructured interview for assessing early experience (e.g., Andrews, Brown, &Creasey, 1990) that allows raters to judge reports of childhood experiences accordingto their own predetermined criteria rather than relying simply on subjects’ ownjudgements about the significance of these experiences. In the interview there are anumber of specific questions such as “Did you feel you could go to your parents if youwere upset or unhappy?” Independently of whether subjects answer yes or no to thisquestion, specific examples of occasions when they could/could not go to their par-ents are elicited and form the basis of the interviewer ratings. In this study ratingswere checked by an independent judge blind to subjects’ group assignment.

Using free recall and cued recall tests on childhood memories, Myers and Brewinreplicated Davis’s (1987) findings that repressors demonstrated longer latencies toreport negative memories than the other groups, but that there were no group differ-ences in recall of positive memories. The exclusively female sample of repressors alsoreported significantly more antipathy, more indifference and less closeness in theirrelationships with their fathers, thus making it extremely unlikely that they had infact had happier childhoods than the other groups.

It is still not clear whether repressors’ performance on autobiographical memorytasks reflects strategies for manipulating their personal histories or whether it is re-lated to the processing of any negative information. To test whether repressors pos-sess an information processing style that affects more than their own personal histo-ries, Myers and Brewin (1995) carried out an experiment that investigated whetherrepressors have a selective deficit in intentionally learning and remembering nega-tive experimental material. On the basis of the previous research, it appeared appro-priate to construct a story that was concerned with parental relationships. The storyconcerned a woman’s childhood with both positive and negative (examples of criti-cism and indifference) information about each parent. Personal relevance was en-hanced by requiring subjects to process the material in relation to the self. As pre-dicted, the female repressors did not differ from controls in their recall of neutral orpositive phrases. They did however show the predicted deficit in recall of negativematerial concerning fathering, as well as impaired recall of the maternal criticalphrase.

The precise relation of the findings of Myers and Brewin (1994, 1995), and thoseof others studying the repressive coping style, to the Freudian view of traumatic earlyexperiences leading to repression is not clear at this point. The childhood interviewdid not result in any dramatic instances of the lifting of repression, but this wouldhave been unlikely given its brevity and the relatively small number of cues provided.At the same time it was not possible to rule out the Freudian hypothesis that therewere additional repressed traumatic memories, involving either maternal or paternalbehavior, that did not emerge in the interview and that could account for the devel-opment of this coping style. An alternative possibility (Dozier & Kobak, 1992; Main,1990) is that early insensitive or rejecting parenting (of which individuals may haveno conscious memory) may have led to deactivation of the attachment system by ex-clusion of attachment-related information. “Rules consistent with such a strategy re-


strict subjects’ awareness and acknowledgment of negative affect, limit recall of dis-tressing or attachment-related memories, and lead to general or vague descriptionsof parents that are not based on actual memories” (Dozier & Kobak, 1992, p. 1474).

Summary

Many important cognitive psychologists, including Bjork (1989), Hasher and Zacks(1988), Neely (1977), and Tipper (1985), propose that selective attention is a highlyflexible, goal-based system consisting of facilitatory and inhibitory processes that op-erate in concert to produce effective and efficient thought and action. This kind offlexible, targetable inhibitory process may be contrasted with more automatic inhibi-tory influences that appear to reflect prior learning and act to assist cognitive process-ing by suppressing related but irrelevant stimuli. The function of both processes is toremove goal-irrelevant information already in working memory and to hinder the ac-cess to working memory of irrelevant information. In each case, as proposed by Pos-ner and Snyder (1975), presentation of a stimulus leads to the initial automatic acti-vation of a range of associated representations. This activation is followed by slowerfacilitatory and inhibitory processes that attempt to limit attention to the most rele-vant representation by affecting the spread of activation in the network.

Not only do inhibitory processes appear to be an essential aspect of everyday cogni-tion, but certain individuals seem to be adept at inhibiting negative information. Intwo studies from our laboratory, we (Myers, Brewin, & Power, 1998) have establishedthat repressors are superior to nonrepressors in their ability to forget negative wordswhen instructed to do so in a directed forgetting task, although they show no differ-ences in their forgetting of positive words. From these data, and the other studies re-viewed above, it appears reasonable to conclude that some individuals have particulardifficulties in the processing of negative information, and that this may be connectedin some way to experiences in childhood. At this juncture we do not know what kindof mechanism is responsible for these effects, or the role played by actual traumaticexperiences. The existence of this group of repressors does however suggest interest-ing possibilities for investigating repression-like effects in the laboratory.

INTEGRATING CLINICAL AND EXPERIMENTAL OBSERVATIONS

As we have seen, the data available are consistent both with some recovered memo-ries being false and others being essentially accurate. In this section we put forwardour own theoretical ideas to explain how essentially accurate memories can be recov-ered after having been forgotten for many years.The clinical phenomena are com-plex, however. Explanations are needed for at least two separate sources of variationin such memories: Differences in the extent of prior forgetting, and differences inthe qualities of the memories recovered.

Variations in Prior Forgetting

The forgetting of traumatic information takes a number of different forms. Amnesiamay be total, with no acknowledgment of the autobiographical fact of the abuse hav-ing taken place. Some people may have a sense that something bad has happened tothem although there is no corresponding explicit memory. In other cases individuals


report knowing they were abused but being unable or unwilling to remember any ofthe circumstances. In still other cases people remember some incidents but are un-able to recall others, or are amnesic for particular aspects of an incident. In manycases representations of traumatic experiences appear in principle to be available,but are rendered inaccessible until triggered by a relevant cue.

Although it is certainly possible that amnesia for some traumatic events reflects in-terference effects or the simple decay of memory traces, the material we have re-viewed also implicates active inhibitory processes in ordinary forgetting. Studies of re-trieval inhibition suggest a mechanism to explain how instructions to forgetgenerated by the self or others might lead to profound amnesia for an event, whichcould subsequently be lifted by exposure to relevant cues. Reports of the circum-stances under which memories are recovered do typically furnish appropriate de-scriptions of cue exposure, with triggers including the respondent’s own childrenreaching an age at which the trauma originally occurred (Andrews et al., 1997b).

Retrieval inhibition in the laboratory, however, is relatively easily overcome by re-presenting the to-be-forgotten items. Of particular interest, therefore, are accounts ofinstances in which individuals have previously been exposed to what seem to behighly relevant cues without triggering recall. For example, a memory of CSA waseventually triggered in one woman by media reports of sexual abuse in a country thatcorresponded to the individual’s own nationality—similar reports of abuse in the UK,to which she had been exposed for many years, were apparently not specific or pow-erful enough to have the same effect. Another woman, a mental health professional,attended courses on sexual abuse without recalling her own abuse, memories ofwhich were not triggered until she attended a course on loss (E. Hunter, personalcommunication, 1996). The converse is that abuse memories have been observed tobe triggered by

rare associates

(Dalenberg, Coe, Reto, Aransky, & Duvenage, 1995). Itis plausible that, in the case of trauma, retrieval inhibition is strengthened by addi-tional inhibitory processes that operate to constrain the processing of common, highfrequency associates of the traumatic event. The failure to process these associates inany depth has the effect of blocking the spontaneous recall of traumatic memories.These same processes may be ineffective, however, when the retrieval cues are un-common associates that have no obvious connection with the forgotten trauma.

Johnson (1994) drew attention to the fact that although there were data to supportretrieval inhibition as an explanation for amnesia following global instructions to for-get, it was a much less plausible explanation for amnesia following specific instruc-tions to forget. In other words, retrieval inhibition may apply to an entire set of itemsin memory and can explain profound amnesia. In the case of partial forgetting, how-ever, the individual has to forget a subset of items from a larger, interrelated itempool, some of which is accessible to working memory. Because there are associativelinks between TBF and TBR items, retrieval of TBR material is likely to be accompa-nied by retrieval of TBF material.

Johnson (1994) argued that once this mixture of TBF and TBR information was inmemory, forgetting could not be explained solely by representational processes oper-ating on the storage of information to prevent retrieval. It would additionally have tobe assumed that some material had been partially retrieved but was not fully pro-cessed or expressed because of the operation of some decisional process. For exam-ple, the person might encounter discriminatory tags on some information whichcould indicate that further processing should be avoided. This kind of model is con-sistent with reports of partial forgetting in which clients describe remaining unaware


of particular aspects of their trauma by choosing not to remember them. They typi-cally describe a state of mind in which they know that they know something, but pre-fer to remain in ignorance of it. Johnson’s account of a postretrieval decisional pro-cess is consistent with the evidence that attention is a flexible process that attempts toensure an efficient stream of thought by inhibiting the entry into consciousness of ac-tivated but irrelevant or unwanted representations. It can potentially account forother instances in which individuals say that they know something has happened butthat they cannot describe it because they have chosen not to think about it.

There remain to be explained people’s reports of a vague sense or suspicion con-cerning past trauma, in the absence of any awareness of avoiding the deliberate pro-cessing or retrieval of related items in memory. As proposed by Freyd (1996), thesemay correspond to implicit memories (i.e., information stored in a form that is notconsciously accessible). Although explicit, consciously accessible memories of traumamay be inhibited, retrieval cues may activate implicit representations that produceemotional or physiological reactions to varying degrees. Such implicit representa-tions may also exist when there have never been any corresponding explicit memo-ries, for example in the case of trauma occurring in early infancy.

Variations in Memory Quality

The survey data previously reviewed indicated that many recovered memories tookthe form of the flashbacks associated with PTSD, being fragmented and experiencedas a reliving of the traumatic event in the present. Other recovered memories ap-peared similar to ordinary autobiographical memories, however, coming back aswhole events and without the element of reliving in the present. These observationsare consistent with the dual representation theory of traumatic memory (Brewin, Dal-gleish et al., 1996). Although other theories have proposed that traumatic memoriesare akin to implicit memories (e.g., van der Kolk & Fisler, 1995), Dual Representa-tion Theory specifies that adult processing of traumatic experience is based on sepa-rate representations supporting explicit and implicit memories.

Flashbacks can be conceptualised as the experience of the activation of memorialrepresentations of trauma that are based on unconscious cognitive processing ratherthan on conscious experience (“situationally accessible memories” vs. “verbally acces-sible memories”; Brewin, Dalgleish et al., 1996). Unlike ordinary autobiographicalmemories, these representations contain codes that can reinstate sensory, emotionaland physiological processes. Although individuals do not have direct access to thesememories, they may become aware of the consequences of memory activation, suchas intrusive images, feelings of panic, and so on. These representations are thereforeby definition dissociated from ordinary memories, but through repeated activationand entry into working memory their content can become integrated with regular au-tobiographical memories.

The fact that flashbacks are based on memorial representations does not meanthat they are necessarily accurate. Cognitive processing of the traumatic event mayhave been influenced by associative links to relevant previous experiences, particu-larly traumatic ones. Therefore, flashbacks may reflect several experiences ratherthan just one, and may have to be interpreted with caution. A dramatic example ofthis process was provided by a member of the emergency services who was treated byone of us for PTSD following his attendance at the scene of a particularly brutal mur-der. Although he had not been present at the murder, he formed an image of this


event that appeared to be influenced by a conscious memory of witnessing his fatherattack his mother when he was 12 years old. Not only did he experience flashbacksbased on this image, but he had intrusive imagery of himself attacking a woman inthe woods near his home using the same stereotyped motions. This image was so vividthat he paid a visit to the woods to confirm that he was not a murderer.

If flashbacks are to become integrated with regular autobiographical memories,the person must be able to consciously edit and manipulate the information providedby the flashbacks within working memory. That is, they must retain awareness thatthey are experiencing the flashback, be able to reflect upon the experience as it is hap-pening, and create ordinary autobiographical memories of the experience. In somecases, however, activation of the situationally accessible memories completely disruptsconsciousness and orientation in present time and space. Subjectively, individuals areunaware of any reality other than the one which is dissociated. When they finish dis-sociating and become reoriented in the present, they may be completely ignorant ofwhat was experienced while in that state. In these cases the traumatic experiences re-main dissociated and integration in autobiographical memory is not possible.

Repression and Dissociation Revisited

Although there is no formal distinction between repression and dissociation (Erdelyi,1990), the cognitive processes underlying repression (in the sense of after-expulsionor motivated forgetting) and dissociation appear to differ in several ways (see alsoTerr, 1994). Ordinarily, autobiographical memories are more or less accessible to be-ing retrieved into “working memory,” a short-term, limited capacity store in whichmemories can be readily rehearsed and edited. A memory that has been repressedmay be thought of as being subject to active inhibitory processes that work to preventit from entering working memory. If this inhibition follows a period of conscious pro-cessing, a repressed memory is in principle no different from any other autobio-graphical memory, although the probability of it being retrieved is by definition verylow. Once retrieved, the new information is free to be edited and to interact with therest of accessible autobiographical memory.

In contrast, retrieval of a dissociated memory will reflect the mental state present atencoding and the fact that there has been little integration of the traumatic experi-ence with ordinary autobiographical memory. Dissociated states, whether consistingof flashbacks, depersonalisation, derealisation, out-of-body experiences, absences, ormore complex alternative personality states, may be conceptualised as modular, in-formationally encapsulated processes that are spontaneously triggered by internal orexternal stimuli. Retrieval is therefore likely to be accompanied by changes in con-sciousness that disrupt working memory and will not guarantee the possibility of in-teraction with the rest of the autobiographical memory system. In these respects theretrieval of a dissociated memory has many of the characteristics of an information-ally encapsulated, modular process being run off.

According to accounts of traumatic amnesia based primarily on dissociation (e.g.,Alpert et al., 1996; van der Kolk & Fisler, 1995), forgetting is primarily due to an en-coding problem. Because the memories receive little processing, they are more easilyforgotten. We would argue, however, that because dissociation does not inevitablylead to forgetting, this explanation requires supplementing. Some individuals retainclear conscious memories of peri-traumatic dissociation. We prefer a term such as

dis-sociative forgetting

, reflecting the fact that both limited encoding and subsequent inhi-


bition of the stored representation are involved. The limited encoding per se will notnecessarily lead to a decreased likelihood of the representation being retrieved by therelevant cues. Indeed, PTSD patients typically experience the repeated activation offragmented, perceptually based memories (Brewin, Dalgleish et al., 1996).

At present a plausible cognitive explanation of primary repression, in which forget-ting is described as immediate and automatic, appears to be farther off. One possibilityworth considering is that dissociative states provide powerful TBF cues by virtue of theirassociation with past episodes involving strategic forgetting. Thus the occurrence of adissociative state may come to be associated with instructions to forget, with retrieval in-hibition being implemented either immediately or at some time over the 24 hours fol-lowing the episode of dissociation. Events experienced in dissociative states are there-fore unlikely to be recalled subsequently unless the dissociative state is reinstated.

Summary

Although repression and dissociation have proved useful in carrying forward the ideaof defensive strategies for forgetting trauma, and can plausibly be used to refer to dif-ferent types of forgetting, we argue that neither is adequate to explain recoveredmemories of trauma. Use of the term

repression

has led to confusion because it can bedefined in two quite different ways, and dissociation, although often coexistent withtraumatic amnesia, is concerned with alterations in consciousness rather than specifi-cally with forgetting. Neither concept can account for the range of empirical data.

An adequate account of recovered memories of trauma must explain the large vari-ations both in the degree of prior amnesia and in the quality of the memories recov-ered. We have argued that these variations may be explicable in terms of three pro-cesses familar to cognitive psychologists, retrieval inhibition, postretrieval decisionalprocesses, and implicit memory. Also integral to the explanation is the idea thatthere are dual representations of trauma in memory, one explicit and deliberately ac-cessible (verbally accessible memory) and one automatically triggered by situationalcues (situationally accessible memory).

CONCLUDING COMMENTS

One could be forgiven, after reading some commentators, for concluding that re-pression was an outlandish notion believed in only by gullible clinicians and with noanalogue in experimental research. In fact this does not seem to be the case, provid-ing we define repression somewhat more narrowly than usual as a decrease in thelevel of activation, and hence of the accessibility of a specific representation in mem-ory, produced by an active inhibitory process. At the most general level, we may notethat an efficient nervous system depends on a balance between levels of activation indifferent systems, increased or decreased by facilitatory and inhibitory connections,respectively. Moreover, the inhibition of behavioural responding is a very importantaspect of the biological response to conditioned stimuli signalling fear or frustration(Gray, 1982). Other distinguished neuroscientists have suggested that repression andrelated phenomena can be explained by the inhibitory effects of fear on central cue-producing responses in the brain (Miller, 1995).

An important task for the future is to understand more about the mechanisms un-derlying false memories, and what discriminates false memories from memories that


are essentially accurate. For example, although the majority of recovered memoriesappear to be based on a specific recollective experience (Andrews et al., 1997b),some are based only on a feeling of “knowing.” However, these two criteria may notbe equally reliable when it comes to establishing the validity of a memory. Recent re-search shows that judgements of knowing in the absence of recollective experienceare more easily influenced by such factors as judgmental strategies and changes inthe leniency of the criteria for deciding what corresponds to a valid memory (Lindsay& Kelley, 1996; Strack & Förster, 1995). Similarly, false memories of events recordedin daily diaries are much more likely when recall is determined on the basis of know-ing in the absence of a recollective experience (Conway, Collins, Gathercole, &Anderson, 1996).

We also need to determine what links the cognitive mechanisms underlying forget-ting to the emotional meanings of trauma. Trauma can be accompanied by feelingssuch as betrayal and helplessness, emotions such as shame, guilt, fear and anger, andthe loss of cherished ideas about personal invulnerability, moral worth, and the abil-ity to predict the future (e.g., Freyd, 1996; Janoff-Bulman, 1992). Although mecha-nisms such as retrieval inhibition, decisional processes, and implicit memory appearplausible candidates to explain forgetting, without a better understanding of why cer-tain events are forgotten, it may be difficult to establish how they are forgotten.

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