Scientists have devised an experiment to test whether out-of-body experiences close to death are a real phenomenon or just a trick being played by the brain.
By Jonathan Amos
BBC News Online science staff, in Salford
Many patients whose hearts have stopped beating claim to have hovered above their bodies and looked down on themselves as others worked to resuscitate them.
Mainstream scientists believe these visions are a fabrication of the mind.
Dr Peter Fenwick, from the Institute of Psychiatry in London, plans to test this view at 25 hospitals across the UK.
He wants to place suspended pictures from the ceilings of accident and emergency units that only someone high up in the room will be able to see.
Patients that survive cardiac arrest will be interviewed to see if they have had an out-of-body experience and whether they saw the pictures.
"We reckon a year will give us 100 people who leave their bodies," Dr Fenwick told the British Association's annual science festival, held this year at the University of Salford, Greater Manchester.
If none of the patients could recall the pictures, Dr Fenwick said, it would suggest the experiences were not real.
"It will show that there is some mechanism in the brain that is creating these scenarios."
He added: "I come at this from the point of view of asking whether there is really a phenomenon here to look at.
"It is of interest because the brain may not be functioning when it happens... but we need real data."
Swiss doctors have previously managed to trigger out-of-body visions by stimulating the brain.
The researchers used electrodes to excite the angular gyrus in the right cortex of a patient.
The doctors did not set out to achieve the effect - it occurred when they were treating a woman for epilepsy.