Debating the deep subconscious: repressed memories

An image of the brain produced by functional magnetic resonance imaging (fMRI), the same method used by Kanaan et al. (Source: Flickr, courtesy of Michael Huang)

An image of the brain produced by functional magnetic resonance imaging (fMRI), the same method used by Kanaan et al. (Source: Flickr, courtesy of Michael Huang)

Over the past century, psychologists, neuroscientists, and clinicians alike have questioned the validity of repressed memories. This controversy has survived for decades in an often-dormant fashion but occasionally rises to the surface as the result of high-publicity court cases or experiments. This debate involves many aspects of repressed memories, such as their definition, reliability, and ability to be studied.  In addition, different authorities study repressed memories, making it difficult to form multidisciplinary theories that capture all of the evidence and adding to the debate’s complexity. Regardless, repressed memories remain a perplexing and interesting topic that deserve objective investigation.

What is repression?

The heart of the debate stems from the definition of a repressed memory, or even just repression. Is repression conscious or subconscious? Is it a defense mechanism? The answers to these questions depend on who is asked.

In his paper “The unified theory of repression,” Matthew Erdelyi claims that Johann Herbart introduced the topic of repression well before Sigmund Freud brought it to popularity with his notions on psychoanalysis (1). Herbart referred to it simply as keeping thoughts below the “threshold of consciousness” and did not consider it to be a defense mechanism – a process undergone to protect an individual from pain caused by the memory of something unpleasant (1).

Erdelyi claims that Freud established the theory that repression is a defense mechanism. When defining repression, Freud stated, “The essence of repression lies simply in the function of rejecting and keeping something out of consciousness” (1). However, he eventually began to discuss repression in two distinct contexts: a narrow context, referring to this specific act of rejecting memories from consciousness, and a broad context, where repression functions as an umbrella term for all possible defense mechanisms.

Erdelyi’s current definition of repression is a direct extension of these two contexts introduced by Freud. He claims that repression can be divided into two processes: 1) inhibitory (or subtractive) processes, which involve damaging a memory, and 2) additive processes, which involve distorting a memory (1). The fact that this theory aligns closely with that of Freud is enough to respark a debate in which Freud’s findings alone have served as fuel for decades. In other words, those who disagree with Freud consequentially disagree with Erdelyi’s definition of repression.

For example, other definitions, such as that of Cheryl Karp, are explained in very different terms. Karp describes repression as a type of “defense operation” that particularly targets procedurally traumatized children and feeds on inner conflict (2). Although these two definitions both speak of damage to a memory, Karp specifically classifies repression as a defense mechanism, while Erdelyi does not. Additionally, Karp makes the association between child trauma and repression very clear even in the definition of repression, while Erdelyi focuses more on the abstract processes of repressing a memory.

Repression versus suppression

Another major point of controversy involving the definition of repression depends on the definer’s position regarding the idea of “suppression.”  Suppression is the deliberate destruction of a memory and was supposedly first introduced by Anna Freud, the daughter of Sigmund Freud, when she differentiated it from repression (1, 2). As a result, Erdelyi claims that Anna Freud became the first person to deem repression an unconscious act (1). Erdelyi, in keeping with Sigmund Freud’s belief in the “continuum of all mental processes” regards repression as either conscious or unconscious (1). Karp, in contrast, specifically distinguishes repression from suppression but states that the latter often leads to the former (2).

In their paper “Can cognitive neuroscience illuminate the nature of traumatic childhood memories?” Schacter et al. (1996) argue that the repression controversy is rooted in this differentiation between “conscious avoidance” and an “automatic, defensive process” (3). Schacter et al. (1996) go on to state that “little or no experimental evidence” exists for the unconscious (automatic) process (3). If this claim were true, it would debase part of Erdelyi’s theory and all of Karp’s.

Who believes in repression?

This point made by Schacter et al. (1996) leads to a second debate regarding the validity of repressed memories that resurface. In other words, are repressed memories real, and can they be trusted? These questions are important, for their answers have implications in the fields of law and medicine. For example, if a middle-aged adult suddenly recovers a memory of repeated abuse as a child, can this memory be used as testimony in court? Also, if memories can be repressed, can they be forcefully resurfaced using therapeutic techniques? These questions have often emerged alongside studies of “false memory syndrome,” where a therapist or scientist has succeeded in drawing out apparently repressed memories of events that never occurred (1).

In their study on the “memory wars,” another name for the repressed memory controversy, Patihis et al. (2013) compared the beliefs of clinical psychologists, research pscyhologists, undergraduate students, therapists, and the general public on the validity of repressed memories. They also compared current beliefs to those from the 1990s to detect possible longitudinal changes. They predicted that “society as a whole, including psychologists, has become more skeptical regarding the accuracy of repressed memories” (4).

One of their major findings was that, at the time of the study, a significantly higher proportion of clinical-psychology practitioners than clinical-psychology researchers believed repressed memories were reliable (4). Overall, they noticed a “shift toward greater skepticism” amongst every group polled, although the trend was more muted for undergraduate students (4).

They questioned roughly 400 students at the University of California, Irvine and found that approximately 81 percent of participants believed that “traumatic memories are often repressed” (4). Additionally, 70 percent agreed with the reliability of memories retrieved during therapy (4). However, 86 percent also conceded that a “memory can be unreliable” (4). As an additional question, the scientists examined how personality characteristics of the students correlated with their opinions on repressed memories. They found that empathy was the only trait associated with a belief in repression (4).

Finally, Patihis et al. (2013) determined that a large rift is still present between researchers and the remainder of the population, with fewer than 30 percent of research psychologists but more than 60 percent of every other participant group believing that “traumatic memories are often repressed” (4).

Neuroimaging and repression

Neuroimaging has emerged as one of the most useful ways to study the human brain, including cognitive processes like forming and storing memories. Indeed, cognitive scientists have conducted several imaging studies of the brain in relation to the idea of repressed memories. For example, Schacter et al. (1996) conducted a magnetic resonance imaging (MRI) study of 22 women with histories of sexual abuse and discovered a “significant reduction (five percent) of left hippocampal volume in abused women compared to non-abused women” (3). The hippocampus is a region of the brain used for forming “explicit or declarative memory,” and damage could result in memory lapses (3). According to Schacter et al. (1996), one possible source of this damage is the toxicity of chemicals called glucocorticoids, which are released into the brain after extended exposure to stress (3). Although this explanation is a possible mechanism for the damage observed in the study, it does not provide conclusive evidence that hippocampal deficits actually cause individuals to forget traumatic experiences.

Schacter et al. (1996) also offer retrograde amnesia as another cognitive model for understanding repressed memories. They define retrograde amnesia as “impaired memory for experiences that occurred before brain injury or psychological trauma,” which can cause sufferers to forget long periods of time after this traumatic event (3). The problem with this theory emerges when one attempts to connect it to the previous MRI study that exhibited hippocampal damage: the particular amnesia that occurs because of hippocampal damage is typically “temporally graded retrograde loss” (3). This means that the most recent memories are more likely to be forgotten rather than memories from childhood – a rule called Ribot’s Law (3).

Schacter et al. (1996) also presented the theory that traumatic events are coded into memory while being exposed to chemicals such as epinephrine and opioid peptides, which are known to prevent the brain from retaining memories (3). Although all of these theories have promising connections to current knowledge regarding repressed memories, further research is needed to support them.

In another imaging study, Michael Anderson et al. (2004) worked with Sigmund Freud’s definition of repression to examine the conscious degrading of memory (suppression). They imaged the hippocampus and lateral prefrontal cortex, an area used in “overcoming interference in a range of cognitive tasks,” in participants asked to actively forget certain word pairs (5). There was indeed increased activity in the entire lateral prefrontal cortex and decreased activity in the hippocampus, suggesting an active process of forgetting (5). Furthermore, this activity was more extreme than that seen in the simple process of forgetting over time (5). While this study sheds light on the process of forced and unforced forgetting, it only holds in the perspectives of those who include suppression in their definitions of repression.

In a final neuroimaging experiment, Richard Kanaan et al. (2007) studied a singular case of a woman with conversion disorder (also called hysteria). This disorder is described as a “psychiatric condition in which patients present with medically unexplained neurological symptoms,” and occurs in up to one-third of neurological appointments, often involving adult women coping with stress (6). In this case, a woman had evidence of a paralyzed limb without medical explanation. She also recently experienced a breakup with a significant other. Scientists determined that shehad emotionally repressed the memory of this breakup, with their argument being that, although the woman remembered the event, she did not acknowledge that it affected her emotionally (6). When researchers examined her brain using functional magnetic resonance imaging (fMRI), they found that three areas of her brain demonstrated different levels of activity when they asked her to remember the “repressed” event versus another stressful event (6). Her amygdala, which controls emotion, and her premotor area, which inhibits activity, were both significantly active, while her primary motor cortex, which controls body movement, showed no movement or sensation in the area corresponding to the paralyzed limb. They concluded that the psychological processes of repressing the memory were associated with the paralysis she experienced.

While this study has implications for those suffering from similar symptoms, it has definite caveats as well. First, as the authors mention, it is only based on one woman. For more support, similar imaging findings should be replicated. Additionally, the conclusion that greater brain activity was correlated with a repressed memory as compared to an equally stressful but not repressed memory rests on the abilities of scientists not only to correctly determine that she had repressed the breakup but also to categorize two disparate events as equally severe. Scientists like Karp, for example, would probably argue that repression does not occur for isolated traumatic events (deemed “Type I trauma”) but rather for those that are repeatedly suffered (“Type II trauma”) (1).

Is there hope for a consensus?

Given the complexity of the debate surrounding repressed memories, consensus among and within disparate groups in society seems unlikely in the near future. A reasonable first step seems to be to reach an agreement regarding a clear definition of repression, if only for the purpose of performing additional studies. Another sensible action is to closely examine the education undergraduates receive regarding the topic, ensuring that it includes representative views from all corners of science. As researchers continue to study repressed memory in increasingly advanced ways, however, it is likely that another debate – one involving the ethics of conducting such studies – will emerge and further complicate an already intricate topic.

References

  1. Karp, C. L. (1995). The Repressed Memory Controversy. Family Advocate, 17(3), 70-71.
  2. Erdelyi, M. H. (2006). The unified theory of repression. Behavioral And Brain Sciences, 29(5), 499-551. doi: 10.1017/S0140525X06009113
  3. Schacter, D., Koutstaal, W., & Norman, K. A. (1996). Can cognitive neuroscience illuminate the nature of traumatic childhood memories? Current Opinion In Neurobiology, 6(2), 207-214. doi: 10.1016/S0959-4388(96)80074-2
  4. Patihis, L., Ho, L. Y., Tingen, I. W., Lilienfeld, S. O., & Loftus, E. F. (2013). Are the “Memory Wars” Over? A Scientist-Practitioner Gap in Beliefs About Repressed Memory. Psychological Science, 25(2), 519-530. doi : 10.1177/0956797613510718
  5. Anderson, M. C., Ochsner, K. N., Kuhl, B., Cooper, J., Robertson, E., Gabrieli, S. W., … Gabrieli, J. D. E. (2004). Neural Systems Underlying the Suppression of Unwanted Memories. Science, 303(5655), 232-235. doi: 10.1126/science.1089504
  6. Kanaan, R. A., Craig, T. K., Wessely, S. C., & David, A. S. (2007). Imaging Repressed Memories in Motor Conversion Disorder. Psychosomatic Medicine, 69(2), 202-205. doi: 10.1097/PSY.0b013e31802e4297
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