Following a traumatic experience, people often have a persistent, yet strangely incomplete, memory for what happened to them. One explanation is that in times of hyper-arousal, such as during trauma, our attention becomes extremely focused on the most relevant details of what’s happening, thus impairing our memory for more peripheral aspects.
To test this idea, Tamara Cavenett and Reginald Nixon recruited a group of 70 skydivers. Half of them learned a list of words in the relative calm of the waiting room prior to a later jump, whereas the other half learned the words while 10,000 feet up in the plane, just before making their skydive. Some of the words were related to skydiving (e.g. parachute), others weren’t (e.g. lamp). The rationale was that the hyper-arousal experienced by the latter group would serve as simulation of the extreme arousal experienced during trauma.
As the researchers expected, at a test later in the day, the participants in the plane subsequently remembered just as many words as the participants in the waiting room. However, crucially, there was a difference in the kind of words most often remembered by the two groups. Compared with the participants who studied the word list in the waiting room, the participants who studied the list in the plane tended to recall fewer of the words that had nothing to do with skydiving, but they remembered more of the words related to skydiving. Recordings of the participants’ heartbeat confirmed the participants in the plane had experienced increased arousal while learning the words, whereas the other participants hadn’t.
The researchers said the findings could help explain the experiences of people who suffer trauma. “Selective processing of relevant details may explain the high incidence of vivid flashbacks and re-experiencing of the traumatic event. Additionally, the inattention to the irrelevant details may account for the overall incomplete and fragmented memory of the trauma often associated with the disorder [PTSD]”.
Cavenett, T. & Nixon, R.D.V. (2006). The effect of arousal on memory for emotionally-relevant information: A study of skydivers. Behaviour Research and Therapy, 44, 1461-1469.