Objective Assessment of Peritraumatic Dissociation: Psychophysiological Indicators

Reviewed by
Priscilla Schulz, LCSW

from an article of the same title by:
Michael G. Griffin, Patricia A. Resick, and Mindy B. Mechanic, University of Missouri - St. Louis

American Journal of Psychiatry, V. 154 (8),
1081-1088, 1997

What is dissociation?
Dissociation refers to the experience in which a person's normal awareness, memory, identity or perception of the environment is temporarily disrupted. It may include:
  • inability to recall important personal information that is not explained by ordinary forgetfulness (dissociative amnesia),
  • confusion about one's identity or the assumption of a new identity (dissociative identity disorder),
  • persistent or recurrent feelings of detachment (depersonalization disorder), or
  • sudden and unexpected travel accompanied by amnesia and confusion about one's identity (dissociative fugue).


What are some theories regarding peritraumatic dissociation and the development of posttraumatic stress disorder?
 Numerous studies in the last decade have noted a relationship between dissociation during a traumatic event (peritraumatic dissociation) and the later development of posttraumatic stress disorder (PTSD). A 1993 study of disaster survivors found that survivors' self-reports of dissociation during the disaster were a significant predictor of later PTSD. In addition, one study of combat
veterans found that both peritraumatic dissociation and current dissociation among combat veterans improved predictions of current PTSD more than veterans' levels of exposure to war zone stress. Researchers theorize that whereas peritraumatic dissociation may be adaptive during a traumatic event, subsequent use of this mechanism for coping with feelings of distress when reminded of the trauma may lead to survivors' failure to process the trauma, both its meaning and the emotions associated with the experience. Ultimately this may result in the development of more severe posttrauma reactions or PTSD.

What is the purpose of this study?
 The main purpose of this study is to objectively measure and assess peritraumatic dissociation and its relationship to PTSD soon after a traumatic event. By doing this, it hopes to fill a gap in the body of knowledge about dissociation and PTSD. In addition it hopes to shed light on the issue of whether there are specific components of posttrauma pathology that inhibit trauma recovery and lead to PTSD. The study's second aim is to improve upon existing self-report measures of dissociation and trauma pathology by comparing responses with objective data in the form of subjects' physiological responses.

Study participants were all recent rape survivors who entered the study within two weeks of the assault. Heart rate and two types of skin conductance responses (similar to what is used in lie-detector tests) were measured while the rape survivors talked about the rape. Self-reports and interview measures of psychopathology and dissociation were also collected on study participants. Care was taken to determine which study participants had dissociated during the rape and those who had not. This was done to assure that comparisons were made between a group who clearly dissociated and a group who clearly had not. Because survivors were assessed only two weeks after the trauma, a diagnosis of PTSD, by definition, was not possible (PTSD symptoms must persist at least one month to be diagnosed as posttraumatic stress disorder); subjects were diagnosed as having or not having symptoms characteristic of PTSD.

What are the study's findings?
    1. There was a significant difference between expressed feelings of distress and physiological measures of distress among subjects identified as high dissociators when they talked about their rapes. More specifically, high dissociators' physiological responses were suppressed (as though they were calm) while retelling the rape and at the same time they reported that they felt very distressed.
    2. High dissociators were more likely to have PTSD symptoms than subjects who did not dissociate during the rape.
    3. High dissociators more than low dissociators rated their rapes as life threatening. Researchers suggest that this finding lends support to theories that peritraumatic dissociation is an adaptive mechanism during trauma, and it is a mechanism that is subsequently used when survivors are reminded of the trauma.
    4. High dissociators appeared to have more severe PTSD symptoms than low dissociators, scoring higher on all three PTSD symptom clusters (arousal, avoidance and reexperiencing) with the biggest difference being avoidance symptoms.
What are the study's implications for working with sexual assault survivors?
    1. Early identification of peritraumatic dissociation in trauma survivors would enable service providers to advise and direct survivors to treatment that could prevent the development of psychopathology.
    2. Clinicians should screen clients for the presence of peritraumatic dissociation and should be aware that clients who dissociated during a sexual assault may have difficulty processing the event in treatment even though they report feelings of distress when discussing the rape.
What were the study's limitations?

Researchers admit that they do not know why high dissociators' expressed distress was incongruent with physiological measures of distress. High dissociators scored higher on measures of depression than low dissociators. Whether depressive symptoms could account for suppressed physiological responses to retelling the rape is not known, but previous research with combat veterans does not support this idea. It is also unclear if high dissociators expressed distress because they believed it was more socially acceptable to say they were upset than to admit feeling nothing or numb when talking about the rape.

Reviewed by Priscilla Schulz, September 1999
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