Involuntary Memories and Dissociative Amnesia

Autobiographical memories of trauma victims often are described as disturbed in two ways. First, the trauma frequently is reexperienced in the form of involuntary, intrusive recollections. Second, the trauma is difficult to recall voluntarily (strategically); important parts may be totally or partially inaccessible—a feature known as dissociative amnesia. These characteristics often are mentioned by posttraumatic stress disorder (PTSD) researchers and are included as PTSD symptoms in the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR as well as DSM-5). In contrast, we have shown that both involuntary recall and voluntary recall are enhanced by emotional stress during encoding. We also have shown that the PTSD symptom in the diagnosis addressing dissociative amnesia—trouble remembering important aspects of the trauma—is less well correlated with the remaining PTSD symptoms than the conceptual reversal of having trouble forgetting important aspects of the trauma. Our findings contradict key assumptions that have shaped PTSD research during the past 40 years.