cont. from

Case studies show that traumatic events in which there is pressure towards secrecy are more likely to induce forgetting as a dissociative defense. For example, a woman who is brutally attacked by a stranger but who receives sympathy, family support, and many opportunities to tell her story, may suffer from PTSD, but is unlikely to develop amnesia for the event. However, a young girl who endures repeated incest with her father and has been sworn to secrecy will more likely have memory impairment for the abuse.

Clinical evidence indicates that the population most likely to develop amnesia for traumatic experiences consists of child victims coerced into silence about repetitive, deliberately caused trauma such as incest or extra-familial physical, emotional, or sexual abuse. Another factor that contributes to memory disturbances is the double-bind felt by children trying to make sense of living in abusive relationships on which they depend for nurturance. Doctors or therapists can have an indication of dissociative amnesia if there are gaps or blank periods in a person's autobiographical memories.

What is known about how memories work?

Human memory is a complex operation. Although there is still much to learn about how memories work, scientists generally understand and accept that there are four stages of memory: intake, storage (encoding), rehearsal, and retrieval. Each of these processes can be influenced by many factors such as developmental stage, setting, expectation, post-event questioning, etc. Even the conditions at the time of the telling of a memory can change the form of the memory, influencing its content and belief in the truth of the memory in the future.

Most scientists also agree that there are two identified forms of memory: explicit and implicit. Explicit memory, also called declarative or narrative memory, is the ability to consciously recall facts or events. This is the form of memory used, for example, when a person recounts the events of his or her day at work or school. Implicit memory, also called procedural or sensorimotor memory, refers to behavioral knowledge of an experience without conscious recall. A person who demonstrates proficiency at reading but who cannot remember how he or she learned the skill is an example of implicit memories in the absence of explicit memories.

Why are traumatic memories controversial?

There are differing schools of thought, grounded in solid research and clinical experience, about the reliability of memory. The details of this scientific debate are often obscure, and the subtleties can be confusing to the public.

Some researchers have proven in the laboratory that ordinary or slightly stressful memories are easily distorted. These scientists are concerned that therapists may be unintentionally distorting the memories of people who report histories of traumatic abuse. This is of particular concern to scientists studying the effects of hypnosis on eyewitness testimony because there is laboratory evidence that setting and expectation can "contaminate" a person's memories.

However, this laboratory research on ordinary memory may be irrelevant in regard to memories of traumatic experiences. Scientists argue that traumatic memories are different from ordinary clinical memories in the way they are encoded on the brain. There is evidence that trauma is stored in the part of the brain called the limbic system, which processes emotions and sensations, but not language or speech. For this reason, people who have been traumatized may live with implicit memories of the terror, anger, and sadness generated by the trauma, but with few or no explicit memories to explain the feelings. Trauma clinicians believe that implicit memories are not easily distorted. It would, of course be unethical to create in a laboratory setting the traumatic experiences necessary to study traumatic memories and their ease of contamination or distortion. For this reason, our knowledge of traumatic memories must come from clinical experience. Clinical data since 1919 has shown a direct correlation between trauma and amnesia or other memory disturbance (Van der Kolk, 1994).

What about memory retrieval long after the trauma?

There is often intense psychological distress when a person is exposed to events which in some way resemble or symbolize the past trauma. These "triggers" may be any sound, smell, or other stimulus such as hot, humid weather which may remind a veteran of his service in southeast Asia, or the smell of a particular cologne which was worn by an abuser.

continue: Should You Believe Your Traumatic Memories?

top . pages 1 2 3 . send to friend . dissociative disorders site map

Reviewed: 04/2006