Published in PLoS One on March 27, 2013, the ULg study included 39 volunteers split into the following groups: 8 people who had experienced an NDE, 6 with memories from a coma but no NDE, 7 who had been in coma but retained no memories, and 18 control subjects. The study used the commonly used Greyson NDE scale to establish the criteria for including people in the study as "experiencers," that is people who have had a near-death experience. This 16-item scale encompasses four dimensions (cognitive, emotional, paranormal and transcendental) and each item can result in a score of 0, 1, or 2. The subject is considered an experiencer if their total score for the 16 questions is 7 or more (out of 32).
The researchers asked participants to recall memories of their NDE or coma, if they had experienced them, as well as emotionally-charged real and imagined memories, both old and recent. An imagined memory is one in which people remember an event that their imagination has entirely made up. For example, the mental image that we form of future vacations or an upcoming birthday party.
The goal was not to analyse the contents of the participants' memories but to evaluate their phenomenological characteristics using a questionnaire. In this case, researchers used the Memory Characteristics Questionnaire (MCQ) developed by M.K. Johnson in 1988 and modified in 2008 by Arnaud D'Argembeau and Martial Van der Linden. The answers to different questions were given a score from 1 to 7. For example, in response to the question of whether a memory included visual details, a score of 1 was given if there were none, a score of 7 if there were many, and a score from 2 to 6 for situations in between. The same format was used for other questions ("Do you remember what you were doing at the time of the event?"; "Do you remember where you were when the event took place?" etc.).
Just like a hallucination
What did the results show? First of all, the overall scores for memories of both real and imagined events were similar in all of the sample's sub-groups and corresponded to existing descriptions in the scientific literature. "This showed us that the participants in our study were quite typical and the ones who had experienced NDEs were no different than others in regards to the phenomenology of their imaginary creations," explains Hedwige Dehon.
Obviously, the NDE memories were of greatest interest. Was their phenomenology closest to that of real or imagined memories? Whether in terms of sensations, emotions, precision, or self-referential details, the NDE memories clearly had the strength of real memories. The scores were even quite a bit higher. "We can almost describe these memories as hyper-reality", says Vanessa Charland-Verville.
One MCQ measurement relates to the frequency of memory recall. It showed that contrary to what we might expect, NDE memories are not recalled more often than the others. "This shows that their phenomenological characteristics (high precision, sensory and self-referential detail) are not the result of incessant recall," explains Hedwige Dehon.
