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Psychological Medicine, 1995, 25, 121-126.

CAN MEMORIES OF CHILDHOOD SEXUAL ABUSE BE REPRESSED?

Harrison G. Pope Jr. and James I. Hudson

From the Biological Psychiatry Laboratory, McLean Hospital, Belmont and Department of Psychiatry, Harvard Medical School, Boston, MA, USA.

SYNOPSIS

We sought studies which have attempted to test whether memories of childhood sexual abuse can be repressed. Despite our broad search criteria, which excluded only unsystematic anecdotal reports, we found only four applicable studies. We then examined these studies to assess whether the investigators: (1) presented confirmatory evidence that abuse had actually occurred; and (2) demonstrated that their subjects had actually developed amnesia for the abuse. None of the four studies provided both clear confirmation of trauma and adequate documentation of amnesia in their subjects. Thus, present clinical evidence is insufficient to permit the conclusion that individuals can repress memories of childhood sexual abuse. This finding is surprising, since many writers have implied that hundreds of thousands, or even millions of persons harbor such repressed memories. In view of the widespread recent public and scientific interest in the areas of trauma and memory, it is important to investigate further whether memories of sexual abuse can be repressed.

INTRODUCTION

Is it possible for victims of childhood sexual abuse to ’repress’ their memories? Many recent writers, both popular and scientific, have suggested that repression is common (Bass & Davis, 1988; Blume, 1990; Fredrickson, 1992; Herman, 1992). On the other hand, experimental evidence for the existence of repression is less convincing. In an extensive review, Holmes (1990) argues that laboratory studies have failed to produce clear evidence for repression, despite more than 60 years of attempts to do so.

Of course, even if repression cannot be induced in the laboratory, it might still occur in real life, such as in victims of childhood sexual abuse. And even if repression occurred in only a fraction of such victims, one would still expect to see many cases clinically, since childhood sexual abuse is common (Nash & West, 1985; Wyatt, 1985; Russell, 1986; Bagley & Ramsay, 1986; Finkelhor et al. 1990; Anderson et al. 1993). Specifically, using the conservative estimate that 10 percent of women and 5 percent of men have endured serious childhood sexual abuse, then 14,000,000 adults in the United States alone are former victims. If repression occurred in only 10 percent of these cases, at least 1,400,000 Americans, and millions more worldwide, now harbor such repressed memories. Given this huge pool of predicted cases, one might expect to find in the literature various published studies of patients exhibiting well-documented cases of repression.

In this paper we review this literature. We first discuss the criteria necessary for a satisfactory confirmation of the hypothesis that repression can occur, and then we examine the relevant studies.

CRITERIA FOR AN ACCEPTABLE STUDY

Evidence that traumatic events occurred

To demonstrate repression, one must first confirm that the traumatic events actually occurred. In many studies of trauma, such documentation is straightforward, because the events are a matter of historical record. Examples include a 4-year follow-up of 26 children kidnapped on a school bus (Terr, 1979, 1983); a study of 16 children who witnessed a parent murdered (Malmquist, 1986); an investigation of 113 elementary school children involved in a sniper’s attack (Pynoos & Nader, 1989); a 4-year follow-up of 34 survivors of a marine explosion (Leopold & Dillon, 1963); an examination of 100 concentration camp survivors 12-20 years afterwards (Strom et al. 1962); and a follow-up of 23 victims of Nazi persecution, half of whom were age 19 or less at the onset of trauma (Chodoff, 1963). Interestingly, although many of the subjects in these studies exhibited severe post-traumatic psychopathology, it appears that no subject in any of these studies developed amnesia. Indeed, many recalled the events in extraordinary detail.

Of course, sexual abuse is more difficult to document than kidnappings, murders, or war crimes. But there are various types of documentation that most investigators would accept: contemporaneous medical evidence of the abuse; photographs; reports from reliable and unbiased witnesses; or confirmation by the perpetrator himself (or herself). Admittedly, many cases of alleged childhood sexual abuse can be neither definitely confirmed nor refuted, but given the large number of expected cases, there should still remain an adequate number sufficiently well-documented for study.

Evidence for ’psychogenic’ amnesia

The second requirement for a satisfactory test of repression is to demonstrate that the victim actually developed ’psychogenic’ amnesia for the trauma. To demonstrate amnesia, one must first exclude cases in which victims simply tried not to think about the events, pretended that the events never occurred, or appeared to derive secondary gain by merely claiming to have amnesia (i.e. to avoid embarrassment or to extend a legal statute of limitations).

Secondly, one must show that the failure of memory exceeds ordinary forgetfulness. Some experiences, though clearly meeting published research criteria for sexual abuse, may not be particularly memorable to a child (for examples, see Pope et al. 1994). Thus, a satisfactory test of the repression hypothesis must demonstrate amnesia for abuse sufficiently traumatic that no one would reasonably be expected to forget it.

Thirdly, to demonstrate ’psychogenic’ amnesia, one must exclude cases in which amnesia developed for some biological reason, such as seizures, alcohol and drug intoxication, or head trauma. This last factor figures strongly in war neuroses: in one study of 200 cases, 50 percent of the soldiers had lost consciousness and another 22 percent were ’dazed’ on the battlefield (Henderson & Moore, 1944). A further biological source of amnesia is the immaturity of the developing central nervous system in young children. Children have nearly complete amnesia for events before the age of three, and substantial amnesia for events before the age of six (Fivush & Hudson, 1990; Usher & Neisser, 1993). Of course, it might be argued that some sexual abuse would be so traumatic that it ought to be remembered even by a child aged five or younger. But again, given the high predicted prevalence of repression, one should expect to find ample numbers of cases without having to rely on under-age-six examples.

Provided that the above exclusion criteria are met, the postulated mechanism of the amnesia -- whether it be called ’repression’, ’dissociation’ or ’traumatic amnesia’ -- is unimportant. It is sufficient that a study should simply exhibit individuals with complete amnesia for well-documented abuse that was too striking to be normally forgettable.

REVIEW OF THE EVIDENCE

In an attempt to find methodologically sound evidence for repression of memories of childhood sexual abuse, we searched the literature for studies that had examined this phenomenon in a series of patients. We included all reports that presented a group of patients analyzed in any quantitative manner; only unsystematic anecdotal reports were excluded. Despite this broad search, we found only four applicable studies in the literature (Herman & Schatzow, 1987; Briere & Conte, 1993; Loftus et al. 1994; Williams,1994). We review these studies below, using the criteria developed above.

The Herman & Schatzow study

In the first attempt to document repression of memories of childhood sexual abuse, Herman & Schatzow (1987) reported on 53 women who they treated in time-limited group therapy for ’incest survivors’. The authors do not specify whether subjects were selected prospectively or retrospectively; it is also not clear whether they represented consecutive individuals or a chosen subsample.

Among the 53 patients, 14 (26 percent) were rated as having ’severe’ amnesia for the presumed incest, and might, therefore, represent examples of true repression. However, since the mean age of onset (+ or - S.D.) of abuse in this group is reported as 4.9 + or - 2.4 years, abuse in some of these women apparently occurred during the period of normal childhood amnesia at age five or earlier. Thus, only a subset of the 14 women in the sample would meet the criterion of displaying full amnesia for events occurring at ages older than five.

But this subset shrinks further, or perhaps vanishes entirely, when we apply the second criterion; namely, the requirement that the abuse be confirmed. Only 21 (40 percent) of the 53 patients obtained ’corroborating evidence’ of the incest, and it is not clear whether these 21 cases include any of the women with ’severe’ amnesia described in the paragraph above. Admittedly, another 18 (34 percent) of the 53 patients were reported to have ’discovered that another child, usually a sibling, had been abused by the same perpetrator’. But the evidence that supported these latter discoveries is not specified, neither does it follow that abuse of a sibling, even if true, confirms abuse in the index case.

In short, it is not certain that any of the 3 subjects met both the criteria of clear amnesia and clear confirmation of trauma. Indeed, of the four cases examples given, three do not meet the criteria (1 and 2 did not have amnesia, and 4 had virtually no confirmation). Case 3 apparently had at least partial amnesia, and good confirmatory evidence. But even this case, it appears, is not actually a real person, since the authors explain that ’all examples cited are composites of several cases’.

Parenthetically, it is curious that Herman (1981) hardly mentions repression or amnesia in her study, Father-Daughter Incest, published only 6 years earlier. In this book, all of the 40 women in the case series displayed apparently clear and lasting memories of their abuse.

The Briere & Conte study

In the second study, Briere & Conte (1993) analyzed questionnaire responses of 450 patients ’with self-reported histories of sexual abuse and who were currently in therapy’. The questionnaire contained a single question regarding amnesia for sexual abuse: ’During the period of time between when the first forced sexual experience happened and your eighteenth birthday was there ever a time when you could not remember the forced sexual experience?’ A total of 267 (59 percent) of the 450 subjects answered ’yes’.

This result is open to several methodological questions. Subjects were ’recruited by their therapists’; further details of the inclusion or exclusion criteria are not provided. It is not clear whether the abuse events were confirmed in any of the cases. Neither is it clear what portion of the subjects had experienced abuse sufficiently traumatic that they would reasonably be expected to remember it always. And, most importantly, a ’yes’ answer on this single question does not demonstrate clear repression of a traumatic memory. A subject answering ’yes’ might mean only that he or she gave no thought to the event during some period, or attempted to deny or minimize the event. No follow-up questions were asked to assess these possibilities.

Finally, some subjects may have been influenced by suggestion. All were in treatment with therapists who were part of an ’informal sexual abuse treatment referral network’, and who, therefore, may have communicated to their patients, explicitly or implicitly, that repression of traumatic experiences was to be expected. With this potential degree of expectation, and with therapists choosing which subjects would receive the questionnaire, it would not be surprising if many subjects answered ’yes’ to a question that asked if there was ever a time when they could not remember an abuse experience.

The Loftus, Polonsky & Fullilove study

Similar limitations affect the recent study of Loftus et al. (1994). In a design comparable to that of the Briere & Conte study, these authors interviewed 52 women with a history of abuse and asked whether they had forgotten the abuse ‘for a period of time and only later [had] the memory return’. In contrast to the 59 percent rate found by Briere & Conte, only 10 (19 percent) of these 52 subjects reported a period of forgetfulness.

However, even the much lower 19 percent figure is subject to the same methodological questions as the previous study; none of the cases of abuse was independently confirmed, neither was the extent or nature of the ’forgetfulness’ investigated. In other words, the evidence does not show that any of the 10 women displayed lasting amnesia for documented events that would normally be expected to be unforgettable.

The Williams study

In the most recent study, Williams (1994) has reported an investigation with more rigorous design. She presents data from interviews of 129 women who, as children, had been brought to a city hospital emergency department in 1973-1975 for treatment and collection of forensic evidence after reported sexual abuse, even if no physical trauma occurred. The abuse was thus documented in medical records and interviews with research staff conducted at the time. The author notes that not all cases were extreme: about a third involved only touching and fondling (Williams, 1992).

The women were aged 10 months to 12 years at the time of the abuse. They were contacted and interviewed approximately 17 years later, at age 18 to 31. They were told that their names had been ’selected from the records of people who went to the city hospital in 1973-1975’ for an ’important follow-up study of the lives and health of women who during childhood received medical care at the city hospital’. The interviewers asked detailed questions about each woman’s history of sexual abuse, including questions about events that the patient herself perhaps did not define as abuse, but which others had. The women were also asked if anyone in their families ’ever got in trouble for his/her sexual activities’. However, it appears that if the subjects still failed to report the known episode of abuse after these questions, they were not asked directly about their documented visit to the hospital to see whether they then acknowledged remembering it.

Forty-nine (38 percent) of the 129 women did not report the abuse event to the interviewer, and Williams speculates that most of these cases represent actual amnesia, rather than voluntary withholding of information. She supports this view by pointing out that many women gave detailed descriptions of other personal or embarrassing childhood events, including other experiences of sexual abuse, while still not acknowledging the index episode.

But it is hazardous to conclude that Williams’ 49 ’non-reporters’ actually had amnesia. In considering this question, it is instructive to examine a similarly designed study by Femina and colleagues (1990). These investigators interviewed 69 young adults (mean age, 24 years) whose histories of abuse (primarily physical abuse) had been extensively documented years earlier during adolescence. On interview, 26 of the 69 subjects (also a proportion of 38 percent) gave responses discrepant with their previously documented histories. In particular, 18 of these 26 individuals were known to have been severely abused in childhood, yet they denied or minimized any experiences of abuse on interview as young adults.

Femina and colleagues then performed a second interview (which they called a ’clarification interview’) with eight of these 18 ’deniers’. When asked directly about their known abuse histories, it appears that all eight individuals admitted that they actually remembered, but had withheld the information during their first interview. For example, one women, ’whose mother had attempted to drown her in childhood and whose stepfather had sexually abused her, minimized any abuse at all on follow-up’. But in the clarification interview, when presented with this history, she admitted, ’I didn’t say it cuz I wanted to forget. I wanted it to be private. I only cry when I think about it’. Similarly, one man, who as a boy was frequently beaten by his father, also minimized any history of abuse on the first interview. When presented with the history in the clarification interview, he acknowledged the beatings but said, ’my father is doing well now. If I told now, I think he would kill himself’.

On the basis of these clarification interviews, Femina and colleagues list reasons for non-reporting of abuse as, ‘embarrassment, a wish to protect parents, a sense of having deserved the abuse, a conscious wish to forget the past, and a lack of rapport with the interviewer’. However, no case of non-reporting was ascribed to amnesia. Given this observation, it would be unwarranted to conclude that the 49 non-reporting subjects in Williams’ study actually had amnesia, since no clarification interviews were performed.

Indeed, the underreporting of life events on interview has been recognized and studied for several decades. For example, a study by the United States national Center for Health Statistics (1961) found that 28 percent of respondents, when interviewed in detail by trained workers, failed to report a one-day hospitalization that they were known to have undergone during the past year. Similar investigations have found that about 30 percent of individuals known to have been involved in an automobile accident (without recorded injury) did not report it on detailed interviews 9-12 months later (National Center for Health Statistics, 1972); 35 percent of another cohort did not report a visit that they had made to a doctor within the past 2 weeks (National Center for Health Statistics, 1965); and 54 percent did not report a hospital admission that they had undergone 10-11 months prior to the date of interview (National center for Health Statistics, 1965). In light of these figures, it does not seem necessary to posit repression to explain Williams’ 38 percent rate of non-reporting for events occurring 17 years earlier.

Williams’ results may also reflect normal childhood amnesia: 25 (51 percent) of her 49 non-reporting subjects had experienced their index episode of abuse at age six or earlier. Indeed, the only case presented in detail in the paper is of a woman whose abuse (of unspecified severity) occurred at age four. And even among individuals who were older at the time of abuse, one must allow for ordinary forgetfulness for events not perceived as strikingly memorable, especially among the one-third of subjects who experienced only touching and fondling. Thus, Williams’ 38 percent rate of non-reporting might be readily explained as a combination of cases of early childhood amnesia, cases or ordinary forgetfulness, and perhaps many cases of failure to report information actually remembered. Additional discussions of methodology of Williams’ study, and some of the other studies analyzed above, may be found in other recent works (Loftus, 1993; Ofshe & Singer, 1994).

DESIGN OF FUTURE STUDIES

Williams’ study provides a useful starting point for the design of a rigorous test of the repression hypothesis. First, one must seek a group of individuals unequivocally documented to have been traumatized, sexually or otherwise. For example, one might begin with a group of medical records, as Williams did, or one could trace all victims identified by a confessed perpetrator or a reliable witness. Opportunities of the latter type are uncommon, but may arise periodically in forensic settings. Secondly, one would select all individuals who were above the age of five at the time of abuse, and who were definitely known to have endured abuse too traumatic to be normally forgettable. Thirdly, one would locate and interview these individuals -- with suitable ethical and therapeutic precautions -- with regard to any past history of trauma. Fourthly, subjects who still denied abuse on this general interview would then receive a ‘clarification interview’ in which they were asked directly about the known abuse event. If some subjects still reported amnesia even in response to the direct questions, this finding would suggest repression.

If one adhered to all aspects of this technique, a study with even a modest number of subjects might provide a useful test of the hypothesis that repression can occur. Indeed, even a series of several case reports, provided that they strictly met the criteria outlined above, could represent persuasive preliminary evidence for the existence, though not for the frequency, of repression.

CONCLUSION

Laboratory studies over the past 60 years have failed to demonstrate that individuals can ‘repress’ memories. Clinical studies, which extrapolate from the laboratory to the study of real-life traumas, must consequently start with the null hypothesis: that repression does not occur.

To reject the null hypothesis, and show that repression of childhood abuse memories can occur clinically, one must meet two requirements. First, one must confirm that traumatic abuse actually occurred. Secondly, one must demonstrate that individuals actually developed amnesia, of non-biological origin (and after the age of five), for this abuse. We performed a literature search for studies that have attempted to document repression of memories of childhood sexual abuse. Despite our broad search criteria, which excluded only unsystematic case reports, we located only four such studies, which we then examined on the basis of the above two criteria. None of the four studies presents data that satisfy both of the two requirements.

It must be emphasized that these four studies are the only applicable studies that we were able to locate. In other words, this brief review does not present merely a selection of the most important studies, but the entirety of all published studies, which to our knowledge have systematically tested whether repression of memories of childhood sexual abuse can occur.

It might be argued that this dearth of studies is due to the difficulty of documenting trauma and demonstrating amnesia. But if repression affects even a small fraction of abused individuals, one would expect hundreds of thousands, if not millions, of current cases in the United States alone, and even larger numbers worldwide. Thus, the difficulties of documenting repression should be more than counterbalanced by the large pool of cases.

In summary, present evidence is insufficient to permit the conclusion that individuals can ‘repress’ memories of childhood sexual abuse. This finding is surprising, since many writers have suggested that there is a high prevalence of repression in the population. Thus, this area of psychiatry begs further carefully designed studies to resolve one of its most critical questions.

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