Trauma and Memory: What we know, what we don’t know and what we know but don’t know we know  

Memory trilogy: Part 2 of 3

It was 10.00pm on 30 October 2002. I was sitting in my car at traffic lights on the crossroads of North Road and Nepean Highway. Out of the corner of my eye, I saw two figures step off the pavement. I didn’t pay attention as it appeared they were crossing the road behind me. Suddenly, the front and back passenger doors were yanked open. Two men jumped into my car wielding blood filled syringes which they held close to my neck, telling me it was HIV positive. They yelled at me to do as they say, and they wouldn’t hurt me. The lights turned green. They instructed me to turn left on to the highway and then down an unlit alleyway. During this short drive they demanded my purse and ATM cards. So began my terrifying ordeal of being carjacked by two men withdrawing from heroin looking for enough money to purchase their next fix.

The next day, I was at the St Kilda Road police station looking through photo albums of convicted offenders. After searching faces in several albums, I spotted one of the offenders. The man in the front passenger seat. He was even wearing the same yellow and black long sleeved t-shirt. I pointed to the photo and said to the police officer, “That’s him”. “How sure are you that’s the man who carjacked you?” he asked. I replied “97% sure”.

A few days later, after a third carjacking, the men were apprehended and charged. Sometime before the court case the police contacted me to collect my denim jacket. They had retained it for forensic testing as it had blood on it from one of the syringes. As I was leaving I asked, “By the way, was one of the men you arrested the man I identified in the photo?” No, was the reply. He was already in prison on the night of the offence.

So it came to pass that my knowledge about trauma and memory became not merely academic but lived experience. In the days after the carjacking, I experienced an acute stress response. I would start at things appearing in my peripheral vision. In a hire car, as mine was stolen during the assault, I was again sitting at traffic lights, this time at the intersection of Nicholson Street and Victoria Parade about four cars back. I absentmindedly watched as a man washing windscreens walked up the line of cars towards me. When he reached my car he stopped and gestured to see if I wanted my screen washed. At that moment, I experienced a full blown anxiety attack. The lights turned green, and I drove across the intersection, pulled over and waited until my heart stopped racing and I could breathe.

False Memory Syndrome proponents might say that my experience supports research findings of expert witness, Professor Elizabeth Loftus. Loftus’s laboratory-based research indicates that a person’s recall of an event can be influenced by or changed by exposure to new information between the event and recall of the event. While the carjacking event was real-life not a laboratory experiment, it could be argued that being given photos to look at primed me to think the police believed the perpetrators to be amongst the offenders in the albums and when I saw a man wearing a t-shirt of the same colours and similar features, I concluded this was their man.

On the one hand, my misidentification of one of the offenders validates Loftus’s research on errors in eye-witness testimony. At the same time, however, it invalidates the false logic of false memory syndrome proponents. Experts in memory and trauma do not disagree that events can be recalled incorrectly or that talking about an event repeatedly can change the narrative. These facts are not disputed. It is a fact that I misidentified the perpetrator, but does it follow that the event didn’t happen, or that other details I described to the police were in part, or in whole incorrect? Is it possible that because I misidentified one of the perpetrators, I had a false memory of being carjacked? Do we throw the baby out with the bathwater?

I do not trivialise the significance of the misidentification. I make the point that this is the kind of detail that would be pounced upon in a court case where Loftus might appear as a defense expert witness. The error I made might be used to invalidate my statement that a carjacking took place.

So, let’s look at the complexity of memory, how normal day-to-day events are encoded, stored and retrieved, and then let’s look at the process of memory encoding and retrieval for traumatic events. To explore these matters, it is important to understand two types of long-term memory, implicit (non-declarative) and explicit (declarative memory).

Implicit memory is not conscious. It does not involve conscious processing at the time of an event. Implicit memories are experienced as strong feelings, emotions or bodily sensations. They do not come with a thought or story about an event. The brain at birth has the capacity for implicit memory. Early memory before the development of speech and other cognitive functions is all implicit (Solinski, 2020). When an implicit memory is activated it appears in the form of bodily sensation, emotion, an unexplained reflex or a reaction to a stimulus.

Explicit memory on the other hand evolves over time as the brain matures from around the age of two. It is a more complex process as other brain functions develop and come online; cognitive, spatial and language. Explicit memory has a story attached to it. There is a ‘sense’ of remembering, including facts and details, as well as a sense of how we know the information (Solinski, 2020).

Memories for recurrent experiences in both children and adults, such as going camping to the same place every summer, can be prone to error, just like single events. We went fishing and had a campfire but specific events on a particular holiday may not be remembered or the person may be confused as to which year an event happened (Solinski, 2020).

The above describes memory related to normal everyday events, some happy or not so happy but in the range of regular day-to-day experiences. What happens to memory when events are terrifying, overwhelming, prolonged and inescapable? What happens to memory when you are a child, and these terrifying events occur at the hands of those with whom you are meant to be safe and protected? What happens to an adult’s memory when they are overwhelmed and frightened for their own safety or the safety of a loved one?

This is the arena where questions about memory have historically been more contentious. There are many reasons for this as discussed in Part 1 of this series, none of which have anything to do with science. It is understandable that a lay person may become confused because ‘experts’ have often heatedly (and at times unprofessionally) disagreed about how memory works. We should remember that two things, even though they are seemingly opposed, can both be true. A memory can be by and large accurate, but also prone to errors.

Traumatic memory, which by its nature involves memory encoded in a highly emotional and physiologically aroused state, can be both more accurate than normal memory and at other times more impaired than normal memory (Brewin, 2011). For victims of traumatic experiences, both children and adults, events can be vividly imprinted, encoded and retrieved in the form of flashbacks, a symptom of post-traumatic stress disorder (van der Kolk, 2014) and can also be forgotten, through the mechanisms of repression or dissociation (Ross & Halpern, 2009). Studies have also shown that in situations of extreme stress or anxiety a person’s eyewitness memory may be negatively impacted for some types of information about the event (Deffenbacher, Bornstein, Penrod, & McGorty, 2004). Memory for peripheral details may be affected while memory for central details can be accurate (Waring, Payne, Schacter, & Kensinger, 2010). The latter two studies describe experiences like the above carjacking.

Oftentimes, words that have specific meanings in one setting may have another meaning in a different setting. Similarly, words can often be used as if they mean the same thing when they describe or represent different meanings or experiences. Following is a brief description of two words, repression and dissociation, which are frequently used interchangeably but have different meanings.

The terms repression and dissociation are often used to describe the disconnection of memory between one part of the mind and another when the disconnection is causing a problem for the individual. In the therapeutic setting, and at times the legal setting, it is important to distinguish which intrapsychic defense is in operation.

There are two types of dissociative experiences. Psychoform dissociation describes a disconnection in consciousness, identity, feelings and perception. Somatoform dissociation describes a disconnection between the conscious mind and bodily sensations and motor control. Both types of dissociation can be measured with questionnaires (Ross & Halpern, 2009).

A helpful metaphor or image is to think about repression and dissociation as horizontal splitting and vertical splitting. Horizontal splitting (repression) describes a metaphorical horizontal barrier in the mind. Above the line is the conscious mind (Freud’s ego) and below the line is the unconscious mind (Freud’s id). Freud described how, in his theory, unacceptable impulses and wishes from the id are kept out of the ego by a horizontal barrier; those thoughts or impulses are pushed down into the unconscious so that they never become conscious (Ross & Halpern, 2009).

In vertical splitting there is a metaphorical barrier within the ego. The vertical split creates compartmentalisation of memory, thoughts, feelings and sensations within the conscious mind. In dissociative identity disorder (DID) the fragmented elements of an event are held by different alter personalities, and each personality is conscious of its own partial memory of the event. One holds the fear, another the physical sensations, and another the information about what happened. An experience can be kept separate (dissociated) as a whole or in its elements; thought can be dissociated from feeling; physical sensation from conscious memory; movement from sensation; and smell from behaviour, or any other combination (Ross & Halpern, 2009). We see this separation in the form of flashbacks, whereby a person may experience overwhelming feelings of fear or rage but have no idea why, or see in their mind disconnected images but have no memory of the event. Studies of war veterans are filled with examples of soldiers known to be in a particular combat zone but having no memory of being there (Van der Hart, Brown, & Graafland, 1999).

External triggers can precipitate a flashback. A client once described being on a platform at Flinders Street station when a man walked past him wearing a particular cologne. He was immediately overwhelmed with feelings of terror and anger but had no idea why. Subsequently, fragments of memory began to surface of abuse by a friend of his father, who wore the same cologne. Similarly, internal triggers can also precipitate a flashback, for example present day sexual arousal in a sexual abuse survivor.

In his book, ‘The body keeps the score’, Van Der Kolk (2014) describes what trauma therapists witness in their consulting rooms daily. We may not consciously know or remember something, but another part of us remembers. We may easily recount in detail a conversation we had with a close friend over dinner last week (non-traumatic events) but may have no recall of the conversation or what we ate if we were in a car accident on the way home. It is also possible that every second of the car skidding across the road and hitting the lamppost is indelibly imprinted on our mind, to be replayed over and over. It may also be possible that we have no recall of the accident (not due to head injury or alcohol consumption) but experience sheer terror when we drive that same section of the road months later.

In the final of this three-part exploration of memory, I will explore ‘therapeutic neutrality’ and the complexities in assisting a client to work with their trauma, what they know, what they don’t know and what they know but don’t know they know.

The acute stress response I described post the carjacking subsided within a couple of weeks. The two offenders were convicted and sentenced to 8 years and 5 years prison. I threw the blood-stained denim jacket away.

Guest Editor: Colin A. Ross MD

Brewin, C. R. (2011). The Nature and significance of memory disturbance in posttraumatic stress disorder. Annual Review of Clinical Psychology, 7(1), 203–227. https://doi.org/10.1146/annurev-clinpsy-032210-104544

Deffenbacher, K.A., Bornstein, B. H., Penrod, S. D.,& McGorty, E. K. (2004). Ametaanalytic review of the effects of high stress on eyewitness memory. Law and Human Behaviour, 28(6), 687–706. https://doi.org/10.1007/s10979-004-0565-x

Ross, C. A. & Halpern, N. (2009) Trauma Model Therapy: A Treatment Approach for Trauma, Dissociation and Complex Comorbidity, Manitou Communications Inc.

Solinski, S. (2020). Recovered Memories of Child Sexual Abuse: Forgetting to Remember and Remembering to Forget, Part 2: The Nature of Memory and Ordinary Forgetting, Frontiers in the psychotherapy of Trauma and Dissociation, Vol 4., International Society for the Study of Trauma and Dissociation

Van der Hart, O., Brown, P., & Graafland, M. (1999). Trauma-induced dissociative amnesia in World War I combat soldiers. Australian and New Zealand Journal of Psychiatry, 33, 37-16.

Van der Kolk, B. (2014). The body keeps the score: Mind, brain and body in the healing of trauma. New York, NY: Viking.

Waring, J. D., Payne, J. D., Schacter, D. L., & Kensinger, E. A. (2010). Impact of individual differences upon emotion-induced memory trade-offs. Cognition & Emotion, 24(1), 150–167. https://doi.org/10.1080/02699930802618918

For people interested in an in-depth exploration of memory, I highly recommend the three part series by Dr Sylvia Solinski referenced below.

Solinski, S. (2020). Recovered Memories of Child Sexual Abuse: Forgetting to Remember and Remembering to Forget, Part 1: A Perennial Controversy, Frontiers in the psychotherapy of Trauma and Dissociation, Vol 4., International Society for the Study of Trauma and Dissociation

Solinski, S. (2020). Recovered Memories of Child Sexual Abuse: Forgetting to Remember and Remembering to Forget, Part 2: The Nature of Memory and Ordinary Forgetting, Frontiers in the psychotherapy of Trauma and Dissociation, Vol 4., International Society for the Study of Trauma and Dissociation

Solinski, S. (2020). Recovered Memories of Child Sexual Abuse: Forgetting to Remember and Remembering to Forget, Part 3: The Role of Dissociation In Extraordinary Forgetting, Frontiers in the psychotherapy of Trauma and Dissociation, Vol 4., International Society for the Study of Trauma and Dissociation