Editing Repressed memory (section)

===Effects of trauma on memory===
The essence of the theory of memory repression is that it is memories for traumatic experiences that are particularly likely to become unavailable to conscious awareness, even while continuing to exist at an unconscious level. A prominent more specific theory of memory repression, "[[Betrayal Trauma Theory]]", proposes that memories for childhood abuse are the most likely to be repressed because of the intense emotional trauma produced by being abused by someone the child is dependent on for emotional and physical support; in such situations, according to this theory, dissociative amnesia is an adaptive response because it permits a relationship with the powerful abuser (whom the child is dependent upon) to continue in some form.

Psychiatrist [[Bessel van der Kolk]]<ref name=Van1995/> divided the effects of traumas on memory functions into four sets:
* Traumatic amnesia; this involves the loss of memories of traumatic experiences. The younger the subject and the longer the traumatic event is, the greater the chance of significant amnesia. He stated that subsequent retrieval of memories after traumatic amnesia is well documented in the literature, with documented examples following natural disasters and accidents, in combat soldiers, in victims of kidnapping, torture and concentration camp experiences, in victims of physical and sexual abuse, and in people who have committed murder.
* Global [[Memory disorder|memory impairment]]; this makes it difficult for subjects to construct an accurate account of their present and past history. "The combination of lack of autobiographical memory, continued dissociation and of meaning schemes that include victimization, helplessness and betrayal, is likely to make these individuals vulnerable to suggestion and to the construction of explanations for their trauma-related affects that may bear little relationship to the actual realities of their lives"
* [[Dissociation (psychology)|Dissociative processes]]; this refers to memories being stored as fragments and not as unitary wholes.
* Traumatic memories' [[Sensory-motor coupling|sensorimotor]] organization. Not being able to integrate traumatic memories seems to be linked to [[posttraumatic stress disorder]] (PTSD).<ref>Diagnostic symptoms of PTSD include reexperience such as flashbacks and nightmares, difficulty falling or staying asleep, feelings of panic or fear, depression, headache, and physiological symptoms including irregular heartbeat and diarrhoea. [http://www.rcpsych.ac.uk/mentalhealthinfoforall/problems/posttraumaticstressdisorder/posttraumaticstressdisorder.aspx Post Traumatic Stress Disorder (PTSD)]. The Royal College of Psychiatrists</ref>

According to van der Kolk, memories of highly significant events are usually accurate and stable over time; aspects of traumatic experiences appear to get stuck in the mind, unaltered by time passing or experiences that may follow. The imprints of traumatic experiences appear to be different from those of nontraumatic events, perhaps because of alterations in attentional focusing or the fact that extreme emotional arousal interferes with memory.<ref name=Van1995/> van der Kolk and Fisler's hypothesis is that under extreme stress, the memory categorization system based in the hippocampus fails, with these memories kept as emotional and sensory states. When these traces are remembered and put into a personal narrative, they are subject to being condensed, contaminated and embellished upon.

A significant problem for trauma theories of memory repression is the lack of evidence with humans that failures of recall of traumatic experiences result from anything other than normal processes of memory that apply equally well to memories for traumatic and non-traumatic events.<ref name="Mcnally1" /><ref name="pmid17803876" /><ref name="Otgaar" /> In addition, it is clear that, rather than being pushed out of consciousness, the difficulty with traumatic memories for most people is their inability to forget the traumatic event and the tendency for memories of the traumatic experience to intrude upon consciousness in problematic ways.<ref>{{cite book | vauthors = McHugh PR | author-link = Paul R. McHugh | title = Try to remember: Psychiatry's clash over meaning, memory and mind | url = https://archive.org/details/trytorememberpsy00mchu | url-access = limited | publisher = Dana Press | isbn = 978-1-932594-39-3 | pages = [https://archive.org/details/trytorememberpsy00mchu/page/n55 45]–6 | year = 2008 }}</ref>

Evidence from psychological research suggests that most traumatic memories are well remembered over long periods of time. Autobiographical memories appraised as highly negative are remembered with a high degree of accuracy and detail.<ref>{{cite journal | vauthors = Berntsen D | title = Tunnel memories for autobiographical events: central details are remembered more frequently from shocking than from happy experiences | journal = Memory & Cognition | volume = 30 | issue = 7 | pages = 1010–20 | date = October 2002 | pmid = 12507366 | doi = 10.3758/BF03194319 | s2cid = 20459653 | doi-access = free }}</ref> This observation is in line with psychological understanding of human memory, which explains that highly salient and distinctive events—common characteristics of negative traumatic experiences—are remembered well.<ref name="Traumatic impact predicts long-term">{{cite journal | vauthors = Alexander KW, Quas JA, Goodman GS, Ghetti S, Edelstein RS, Redlich AD, Cordon IM, Jones DP | display-authors = 6 | title = Traumatic impact predicts long-term memory for documented child sexual abuse | journal = Psychological Science | volume = 16 | issue = 1 | pages = 33–40 | date = January 2005 | pmid = 15660849 | doi = 10.1111/j.0956-7976.2005.00777.x | s2cid = 8750819 }}</ref> When experiencing highly emotional, stressful events, physiological and neurological responses, such as those involving the [[limbic system]], specifically the [[amygdala]] and [[hippocampus]], lead to more consolidated memories.<ref>{{cite journal | vauthors = Buchanan TW | title = Retrieval of emotional memories | journal = Psychological Bulletin | volume = 133 | issue = 5 | pages = 761–79 | date = September 2007 | pmid = 17723029 | pmc = 2265099 | doi = 10.1037/0033-2909.133.5.761 }}</ref> Evidence shows that stress enhances memory for aspects and details directly related to the stressful event.<ref>{{cite journal | vauthors = Shields GS, Sazma MA, McCullough AM, Yonelinas AP | title = The effects of acute stress on episodic memory: A meta-analysis and integrative review | journal = Psychological Bulletin | volume = 143 | issue = 6 | pages = 636–675 | date = June 2017 | pmid = 28368148 | pmc = 5436944 | doi = 10.1037/bul0000100 }}</ref> Furthermore, behavioural and cognitive memory-enhancing responses, such as rehearsing or revisiting a memory in one's mind are also more likely when memories are highly emotional.<ref>{{cite journal | vauthors = Christianson SA | title = Emotional stress and eyewitness memory: a critical review | journal = Psychological Bulletin | volume = 112 | issue = 2 | pages = 284–309 | date = September 1992 | pmid = 1454896 | doi = 10.1037/0033-2909.112.2.284 }}</ref> When compared to positive events, memory for negative, traumatic experiences are more accurate, coherent, vivid, and detailed, and this trend persists over time.<ref>{{Cite journal|last1=Peace|first1=Kristine A.|last2=Porter|first2=Stephen | name-list-style = vanc |date=2004|title=A longitudinal investigation of the reliability of memories for trauma and other emotional experiences|journal=Applied Cognitive Psychology|volume=18|issue=9|pages=1143–1159|doi=10.1002/acp.1046|issn=0888-4080}}</ref> This sample of what is a vast body of evidence calls into question how it is possible that traumatic memories, which are typically remembered exceptionally well, might also be associated with patterns of extreme forgetting.

The high quality remembering for traumatic events is not just a lab-based finding but has also been observed in real-life experiences, such as among survivors of child sexual abuse and war-related atrocities. For example, researchers who studied memory accuracy in child sexual abuse survivors 12 to 21 years after the event(s) ended found that the severity of posttraumatic stress disorder was positively correlated with the degree of memory accuracy.<ref name="Traumatic impact predicts long-term"/> Further, all persons who identified the child sexual abuse as the most traumatic event of their life, displayed highly accurate memory for the event. Similarly, in a study of World War II survivors, researchers found that participants who scored higher on posttraumatic stress reactions had war memories that were more coherent, personally consequential, and more rehearsed. The researchers concluded that highly distressing events can lead to subjectively clearer memories that are highly accessible.<ref>{{Cite journal|last1=Thomsen|first1=Dorthe Kirkegaard|last2=Berntsen|first2=Dorthe| name-list-style = vanc |date=2009|title=The long-term impact of emotionally stressful events on memory characteristics and life story|journal=Applied Cognitive Psychology|language=en|volume=23|issue=4|pages=579–598|doi=10.1002/acp.1495}}</ref>