Evolution-prepared dissociation provides a hyper-clear picture of the dangerous circumstances that evoked it. In contrast, non-evolution-prepared peritraumatic dissociation does precisely the opposite — it distances, obscures, pushes away, avoids, hides, and blocks a clear picture of the dangerous circumstances that evoked it. Researchers’ failure to distinguish between these opposite kinds of dissociation has prevented us from obtaining a clear empirical picture of (1) these two kinds of dissociation, and (2) their respective relationships to posttraumatic psychopathology (i.e., acute stress disorder [ASD], PTSD, and the dissociative disorders).
As noted in UnderstandingDissociation.com’s last post (and in comments from several of you), evolution-prepared dissociation involves accelerated mental processing, a hyper-focus on the details of the dangerous situation, a subjective slowing of time, and a dissociative suppression of fear, pain, and other disruptive emotions. This ‘package’ of responses is a ‘gift’ that natural selection has given us. It is highly adaptive and it maximizes our ability to take effective action and, thereby, survive an imminently lethal situation.
Note: “peritraumatic” literally means ‘near or around the time of the trauma.’ Contrast evolution-prepared evolution with DSM-IV’s description of peritraumatic dissociation:
“a subjective sense of numbing, detachment, or absence of emotional responsiveness; a reduction in awareness of his or her surroundings; derealization; depersonalization; or dissociative amnesia…” (American Psychiatric Association, 2000, p. 469)
This view of peritraumatic dissociation is inseparable from the idea that dissociation is a defense mechanism. For example:
“Dissociation leads to inner distancing and is thus to be regarded as a fundamental withdrawal mode enabling the person in question to phase out the unbearable reality for the moment and pretend that it has never happened.” (Breh & Seidler, 2007, p. 54)
Research on Peritraumatic Dissociation
Neither the researchers of peritraumatic dissociation, nor the instruments that they use to measure it, have drawn a clear distinction between defensive peritraumatic dissociation (which seeks to avoid reality) and adaptive evolution-prepared dissociation (which shines a bright spotlight on reality)! No wonder the research on dissociation that occurs near or around the time of the trauma (i.e., both kinds of dissociation) has produced modest and inconsistent results. Specifically, instruments that indiscriminately mix defensive peritraumatic dissociation with adaptive peritraumatic dissociation produce scores that are only modestly related to subsequent PTSD symptoms (Effect size = .34-.36). This effect size is significant, but not especially impressive.
On the other hand, researchers who have distinguished between immediate peritraumatic dissociation and peritraumatic dissociative symptoms that persist for weeks have found a very different result. Their multivariate statistical analyses show that immediate peritraumatic dissociation is unrelated to subsequent PTSD, whereas persisting peritraumatic dissociative symptoms are highly related to subsequent PTSD (Briere, Scott & Weathers, 2005). Similar results have been reported by other researchers (Halligan, Michael, Clark & Ehlers, 2003; Murray, Ehlers & Mayou, 2002; Panasetis & Bryant, 2003) .
It is important to note, however, that peritraumatic dissociation (whether immediate or persistent) is not the whole story when it comes to developing PTSD. That is, the same studies that revealed the importance of persisting peritraumatic dissociative symptoms also showed that
(1)many persons with no peritraumatic dissociation go on to develop PTSD, and
(2) many persons experience peritraumatic dissociation, but do not develop PTSD.
The Next Question About Dissociation
The next big question about dissociation at this point in our discussion is: “How and why does peritraumatic dissociation persist in some people?“ And perhaps become chronic? And why and how does peritraumatic dissociation persist a bit for some individuals, but then ultimately subside without any psychopathological after-effects?
What do you think?