One in 10 people has had an out-of-body experience, yet scientists know very little about the phenomenon. Researchers say a new study could bring us closer to the ultimate question of what happens when we die.
David Wilde says the experience is rather like a dead arm
Out-of-body experiences involve a sensation of floating and seeing the physical body from the outside. They are often a symptom of the near-death experience, where people, whilst apparently dead, experience visions, tunnels of light and a feeling of peace, before being resuscitated.
These experiences are reported across many cultures and "experiencers" often cite them as life-changing events. Preliminary studies have shown that certain populations are more susceptible. Among students, for example, the incidence of out-of-body experiences (OBE) rises to 25%.
A team of scientists at the University of Manchester aims to study profile those who have and haven't had OBEs. Using an online questionnaire on body perceptions and experience, they aim to isolate differences between these groups. The survey will also gather details on the different kinds of OBEs people have, to categorise these experiences more precisely.
"There are several theories as to why people have OBEs," says David Wilde, the researcher running the project. "A common link between them is the idea that in certain circumstances the brain somehow loses touch with sensory information coming in from the body. This triggers a series of psychological mechanisms which can lead to someone having an OBE."
Mr Wilde draws an analogy with the experience of a dead arm.
"It's a little bit like if you sleep on your arm and lose sensation in it. Only with an OBE, the sensation loss is in the whole body and the brain's response seems to be to create a feeling of separation from the self."
"In this study we aim to take the theory a stage further, by looking at the way people see and experience their bodies, and how - through perfectly ordinary psychological processes - these images and experiences may create the impression of seeing their bodies from the outside."
It isn't rare for people to have more than one OBE, and they may also occur as part of the wider near-death experience (NDE) some report experiencing in life-threatening circumstances.
Mr Wilde is at pains to stress that he doesn't judge whether OBEs are real.
"If someone has had an experience, then we take that as real. We can't disprove or prove anything."
A different research approach comes from Dr Sam Parnia, who studies OBEs as part of his interest in near-death experiences. He is looking at reports of OBEs from cardiac arrest patients. He is conducting a national study, looking at physical factors that might cause this experience.
Sam Parnia is looking at oxygen, CO2 and salt levels among patients
Reports of OBEs and NDEs are often simply anecdotal, but the hospital environment allows Sam Parnia to monitor and compare oxygen, carbon dioxide and salt levels in the patients who did and did not have either experience.
His study also involves a novel method of testing if the "self" actually does leave the body during an OBE. Sam has suspended boards below the ceiling and these have images on the upper side. The idea is that if people do look down from above, they may recall the extra information. As yet, no patients have reported seeing these images.
Whether these phenomena are visions of a dying brain or paranormal activity, Dr Parnia says science needs to offer an explanation of what happens when we die.
"I think that NDEs hold the key to finally solving this mystery. In studying them further we will be able to discover the true nature of the relationship between the mind and the brain and answer the wider questions regarding the existence of an afterlife."
David Wilde's survey can be seen using Internet links (above right). It is available for the next two weeks, and a summary of the results will be posted on their web page.
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