I've written before about near-death experiences and what they can prove about the existence of the soul. Now another study has come to my attention, one that has an even more potent conclusion. (HT: Boing Boing)

It's long been known that the content of NDEs is influenced by religion and culture. People who have them consistently encounter the kind of afterlife they expect and meet the religious figures they've been taught to believe in. For example, while Christian NDEs often include Jesus or angels, Hindus report NDEs in which they meet Hindu gods, or a clerk in a celestial bureaucracy who says that there's been a paperwork error and someone else with the same name was supposed to die instead.

This suggests that NDEs, rather than a glimpse of another reality, are brain-generated experiences. Like dreams or hallucinations, they're shaped by people's background beliefs and expectations. And there's more evidence for this in a 1990 article in the Lancet, with the wonderfully sardonic title, "Features of 'near-death experience' in relation to whether or not patients were near death". (The abstract is online, as is full text.)

As the article says:

The medical records of 58 patients, most of whom believed they were near death during an illness or after an injury and all of whom later remembered unusual experiences occurring at the time, were examined. 28 patients were judged to have been so close to death that they would have died without medical intervention; the other 30 patients were not in danger of dying although most of them thought they were.

There were some differences between the two groups. People who were genuinely near death were more likely to report perceiving some kind of strong light (whether diffuse, at the end of a tunnel, or emanating from people they saw during the NDE). They were also more likely to report "enhanced cognitive function", including greater speed or clarity of thought or unusually vivid sensory perceptions. However, when it comes to the "classic" NDE elements, the sense of leaving one's body and of experiencing a "life review", there was no difference between the people who were actually near death and those who weren't:

Belief in having left the body and seeing it from above. The two groups showed no difference in this belief. 68% of both groups reported this belief.
Memories of earlier events in life. The two groups also did not differ in proportions reporting memories of earlier events in the subject's life (sometimes called "life review" or "panoramic memory"). 6 (27%) of 22 patients near death and 4 (17%) of 23 patients not near death reported some such memories. Most patients reported only a few memories; only 2 (9%) patients near death and 2 (9%) patients not near death reported a review or replay of his or her whole life.

Some of the patients who were not near death were judged to have no serious illness or injury; others had a serious illness or injury, but not one that put them in danger of dying. Regardless, they believed they were dying or near death, and they had NDEs that seemed indistinguishable from those of people who had serious impairment of vital signs and would have died without medical intervention. The conclusion is clear: NDEs are the product of imagination, of a brain that thinks it's dying, whether it actually is or not. As the authors of the paper say:

The psychological interpretation receives support from the evidence that persons who are not near death (from illness or injury) may have experiences that in all respects resemble those of persons who are near death. It would seem that among those who were not near death their experiences were precipitated by their belief that they were.