Under the Microscope / Prof William Reville: An out-of-body experience (OBE) is the sense of leaving one's physical body while fully conscious, and viewing the surroundings from another vantage point. Around one in 10 people experience this bizarre sensation at some time.
The OBE phenomenon raises profound questions about the nature of consciousness and, at first glance, indicates that the mind can exist independently of the brain. However, many scientists who study the phenomenon are convinced that OBE merely represents the brain's ability to distort perceptions of reality. Robert Matthews summaries current knowledge of OBE in BBC Focus magazine, October 2005.
The fundamental nature of mind is one of the biggest mysteries confronting science. There are two schools of thought. One is that the mind is simply what the brain does. The other is that, although the mind acts through the brain, it is not identical with the brain. Most scientists would take the former view and would be very sceptical of any suggestions that the mind is other than a 100 per cent manifestation of underlying physical activities. But even the sceptics do not doubt the reality of the OBE phenomena. There is no debate about the reality of OBE, but there is a debate about what it means.
OBE is under active scientific investigation in many parts of the world. One fascinating observation is that OBE can be triggered by electrical or magnetic stimulation of the angular gyrus in the temporal lobe of the brain. This region has many roles including object perception, spatial awareness and logical sequencing. If something is wrong there, the patient might put his trousers on before his underpants and not see anything wrong (perhaps this is Superman's problem). The patient might also feel that one or other limb is not connected to his body, and he can't make it work.
It has been noted that epileptics are particularly prone to experience OBE when their seizures occur in the temporal lobe. Sleep and oxygen deprivation have also been shown to trigger OBE, and 18 per cent of test pilots who pass out when exposed to high G-forces during training also experience OBE. Besides epilepsy, other medical disorders that can trigger OBEs include migraine and psychosis. Many scientists are convinced that these various findings show that the OBE phenomenon is simply caused by altered brain activity and erase the need to invoke theories about disembodied minds.
However, some things have been reported associated with OBEs that, on the face of it, could not be explained on the simple basis that the brain is the mind. For example, in 1994 a woman in Seattle had a heart attack and was rushed to the hospital resuscitation unit. She claimed later that during resuscitation she felt that she had floated from the room and out of the building and, while outside, she saw a dark trainer, scuffed on the left side, on a window ledge on the third floor. Her social worker checked and found the runner on the ledge. She also noted that the scuffing could only have been seen from outside the building and above the window.
Many such stories are reported in the literature. A most interesting class of case are those hospital patients who technically die on the operating table but then recover and report having an out-of-body experience during the period when monitoring equipment could detect no brain signals. One woman in this condition later reported that she saw and heard the surgeons who operated on her and she accurately described devices that would be seen only by specialist surgeons.
Prospective studies are being carried out to test the validity of stories told by patients who report having an OBE during resuscitation when they were brought back from the brink of death. In these studies unusual objects are placed in normally inaccessible places around the resuscitation room, eg photographs are suspended from the ceiling with the photo side pointing upwards. All patients are then interviewed after resuscitation and those who report an OBE during the operation are asked if they saw any of the planted objects. So far these studies have produced no conclusive results.
What sort of people experience OBEs? This question was investigated by researchers at Oxford University who compared the psychological profiles of 450 people who had experienced OBEs with the profiles of 200 randomly chosen people. The results showed that people who experienced OBEs have a tendency towards a trait known as schizotypy. Such people tend to have somewhat eccentric beliefs and perceptions, but it is a fairly benign personality trait. They can function perfectly well in society, but during times of stress, tend to have OBEs. The OBEs may be a helpful coping strategy.
Most OBEs are involuntary, but some people claim they can induce OBEs by entering a sort of trance. They visualise themselves leaving their bodies either by floating off or by climbing up on a rope. Some drugs also increase the chances that some people will experience an OBE.
If you want to participate in a study into the nature of OBE you can take part in a Manchester University study of the way people perceive their own bodies. Visit www.freeresponse.org/muobe2005/index.aspx.
The mind-body problem in science will be with us for a very long time. Perhaps the OBE phenomenon will shed some light on it. I never had an OBE experience myself, but I have been out of my skull a few times. Much drink was involved.
William Reville is associate professor of biochemistry and public awareness of science officer at UCC (http//understandingscience.ucc.ie)