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Near Death Experiences

Research Scales Used to Classify an NDE

Near Death Experiences Series, Article 12 (Reviewed by the Editorial Board)

The need for a classification system

Perhaps some of us, or some of our friends or acquaintances have experienced a sense of joy, happiness, or even seen a bright light, or perhaps have sensed they were going through darkness, or a maybe even a tunnel, but can we say whether they have experienced an NDE? Probably not!! This is the reason why one of the key questions that needs to be examined in the study of the NDE phenomena, is a classification system. This system should be sensitive enough to catch most of the experiences but not so sensitive as not to be able to distinguish them from other similar mental states.

By looking at the features described by Moody and other investigators it is obvious that many of the features that make up these experiences are by no means specific to only those who have come close to death. In fact there are many examples of people who were physically not close to death, having feelings of joy and peace and/or seeing a bright light, or feeling as if going through a tunnel. In fact the feeling joyous or seeing a light can occur under many other circumstances that do not relate to being close to death. In order for an experience to be defined as a near death experience there needs to be a series of common features and not just one or two so that these mental states can be set apart from other similar mental states.

The construction of research scales

So how might we differentiate between these mental states and other experiences similar but yet clearly different? Obviously a research scale is needed. Two American investigators in the 1980s set out to answer this problem and each of them constructed a scale using slightly different criteria. These scales were easily administered and it was claimed they could determine the presence or absence of an NDE. 

The importance of these scales for research into the near death experience phenomena, cannot be stressed enough. When looking at the literature, a number of studies exist where proper classification systems have not been used and this unfortunately makes their results difficult to interpret. This is because it is unclear whether the experiences being studied are near death experiences or other similar mental states. In these studies investigators asked subjects only about their nearness to death and their beliefs and not about the features of their experiences. This is quite a different approach from the phenomenological approach that characterizes the 2 scales referred to above. So it is difficult to tell what these studies were showing.

Studies without proper research scales

One of the above studies examined the role of sleep patterns and NDEs, in a sample of 55 patients. They concluded that they could be related (1). However there was no evidence that near death experiences were similar to the mental states they were talking about, and more important the physiology of the two states was quite different. Another study (2) that received wide spread attention in the press, examined how carbon dioxide could explain the occurrence of NDEs.  The most telling point against carbon dioxide levels as a cause for near death experiences is shown by cardiac arrest NDEs where all patients have high carbon dioxide levels but only 10% have these experiences.

Two more studies that obtained extensive media coverage were conducted by Professor Olaf Blanke and his team. The first of these (3) concluded that out of body experiences are simply illusions, brought about by an abnormally functioning brain. The cases that have been described do not in fact resemble out of body experiences as described by those who have had an NDE. So there is nothing to suggest that NDEs are the same. This suggestion is still highly debatable and likely to be wrong.

In the second article, authors claimed to have induced out-of-body experiences in the lab, by convincing volunteers that they were actually sitting or standing outside of their own bodies, watching themselves from behind. Scientists induced this illusion in healthy volunteers by using the methods of virtual reality (if you wish to know more, see reference 4). In other words, authors concluded that humans’ normal experience, where the conscious self is localized within their bodily borders, can be made to break down artificially in the lab by using illusion and deception. However, it is clear that the term out of body experiences was inappropriately used to describe a situation where the brain was simply tricked, and they did not make it clear that out of body experiences may have different causes and that they were only talking about one particular kind. This error would lead people to think that all out body experiences are illusions. Had the authors used an appropriate, widely accepted classification scale for out-of-body experiences, this simplistic and gross error would have been avoided.  It is also sad to see that this erroneous interpretation of the results obtained has been widely reported in the press.

....... If you want to know more, visit the near death experiences section of our web site (5)


(1) Nelson, K., et al., 2006, “Does the arousal system contribute to near death experience?” Neurology, 66:1003-9

(2) Klemenc-Ketis, Z, et al., 2010,“The effect of carbon dioxide on near-death experiences in out-of-hospital cardiac arrest survivors: a prospective observational study.” Crit Care. 2010;14(2):R56.

(3) Blanke, O. et al., 2002. Neuropsychology: Stimulating illusory own-body perceptions. Nature 419, 269-270

(4) http://notexactlyrocketscience.wordpress.com/2007/08/27/virtual-reality-illusions-produce-out-of-body-experiences-in-the-lab/

(5) Near Death Experiences

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