Involuntary Memories and Dissociative Amnesia: Assessing Key Assumptions in PTSD Research

Abstract

Autobiographical memories of trauma victims are often described as disturbed in two ways. First, the trauma is frequently re-experienced 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 are often mentioned by PTSD researchers and are included as PTSD symptoms in the DSM-IV-TR (American Psychiatric Association, 2000). In contrast, we show that both involuntary and voluntary recall are enhanced by emotional stress during encoding. We also show 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 over the last 40 years.

Figure 1

Frequency rating of voluntary and involuntary memories as a function of valence in the top panel and intensity in the bottom panel (Experiment 1). Error bars are standard errors.

Figure 2

Distribution of responses as a function of their reported frequency of recall in Experiment 2. The top panel is for negative events and the bottom panel is for important events

Figure 3

The reported frequency of recall of voluntary and involuntary memories as a function of valence in Experiment 2. Error bars are .05 confidence intervals.