To scientists, nothing is as frustrating as the popularity of the paranormal.
Despite centuries of success with the scientific method, belief in psychic powers and other paranormal phenomena survives. Polls generally show that more than half the people questioned say they believe in psychic phenomena.
Psychologist Sabine Backman suggests belief in psychic phenomena is not really so mysterious. Many people believe in the paranormal because they believe they have experienced psychic phenomena themselves.
"First, they might really have experienced the paranormal," she wrote in a recent issue of the British magazine New Scientist. "If true, we need to rewrite much of science, and soon."
Second, she says, "they might be making it up." This explanation no doubt applies to many such reports, but some people certainly are sincere. In those cases, Backman says, "they might be misinterpreting perfectly normal events - suffering from what we might call a paranormal illusion."
There isn't any doubt that the brain constructs illusory images from the information the senses provide. Many common optical illusions illustrate how sight can be deceptive.
Such illusions occur because the brain must interpret and reconstruct all the weird sights and sounds that it constantly encounters. Instead of a blur, we see forms and figures that the brain has constructed from the information available to it. Sometimes those constructions don't quite correspond to what we would see with a closer, more careful look.
Other alleged psychic experiences, she says, may simply be misinterpretations of coincidences. Some coincidences aren't as unlikely as they seem - as when a dream supposedly comes true.
In fact, she asserts, "misjudgments of probability" may be to blame for most paranormal beliefs.
She offers as an example the common experience of dreaming that a friend or relative has died, then discovering the next day that the person has in fact just died. To any individual, this seems an extraordinary coincidence. Many would interpret it as a sign of something psychic. But is such a coincidence terribly unlikely? Not really.
Backman cites an analysis by statistician Christopher Scott showing that even if a person has only one dream about a friend's death in a lifetime, there would be 2,000 such dreams per night among the 55 million inhabitants of Great Britain. Roughly 2,000 people per day also die in Great Britain. There are therefore many opportunities for a dream and a death to coincide.
Backman addresses another common paranormal favorite, the "near death" experience, in a contribution to a new book called Frontiers of Science. Many people revived from a near-fatal condition have reported a weird sensation of travelling down a dark tunnel toward an eerie light. Such experiences seem to happen too often, and reports from different people are too similar to be fabrications; they must have some meaning. Blackmore points out that the meaning need not be supernatural, though.
Analysis of certain brain structures suggests a tunnel illusion would be just what's expected in a person suffering from lack of oxygen - a common near-death circumstance. People near death have similar experiences because they have similar brain structures.
"According to this kind of theory, there is, of course, no real tunnel," Backman writes. "Nevertheless there is a real physical cause of the tunnel experience. It is due to random noise in the visual cortex (a region of the brain). In this way we can explain the origin of the tunnel without recourse to other worlds and without dismissing it as `just hallucinations.' "
So it seems that science has perhaps pursued the wrong strategy in trying to dismiss and debunk paranormal experience. Understanding it and explaining it may be a much more fruitful approach to doing away with it.