About Rationally Speaking
Rationally Speaking is a blog maintained by Prof. Massimo Pigliucci, a philosopher at the City University of New York. The blog reflects the Enlightenment figure Marquis de Condorcet's idea of what a public intellectual (yes, we know, that's such a bad word) ought to be: someone who devotes himself to "the tracking down of prejudices in the hiding places where priests, the schools, the government, and all long-established institutions had gathered and protected them." You're welcome. Please notice that the contents of this blog can be reprinted under the standard Creative Commons license.
Tuesday, October 17, 2006
Out of body? Nope, inside the mind!
Blanke and colleagues have shown that small electrical currents in certain areas of the brain involved with multi-sensorial perception, such as the angular gyrus, cause the distinct sensation of out-of-body experience or of a strange presence in the room. One patient had the feeling of hanging from the ceiling, another was sure that there was a presence behind her, and a third one felt a “shadow” next to her, attempting to interfere with her activities. These experiences are repeatable under laboratory conditions, which means that a hallmark of parapsychology – out of body experiences – can actually be turned on or off at will by the experimenter, has been traced to perturbations of specific circuits in the brain, and of course has absolutely nothing supernatural about it.
The explanation for this class of neurological phenomena is similar to that of the so-called “phantom limbs,” truly bizarre experiences that were once relegated to purely psychological phenomena but are now understood as a byproduct of the normal functioning of the brain. In the case of phantom limbs people who have lost, say, a leg or an arm keep complaining of itches, or even pain, emanating from where the limb used to be. Until a few years ago these patients were thought to suffer from psychological damage at the shock of losing a part of their body and to react with, essentially, wishful thinking that the part were back into place. It turns out that the severed nerve endings keep sending signals to the brain, which attempts to make sense of them while re-wiring the sensorial circuits. It is this disconnect between the wiring of the nervous system and the mental map of one's body that generates the weird sensation of a phantom limb. The feeling, incidentally, often disappears months or years after the injury, once the brain has had time to rewire its sensorial circuits and properly adjust to expectations concerning the spatial extent of the body.
The phenomena studied under controlled conditions by the Swiss group occur in normal people as well, as a result of a variety of factors including extended sensorial deprivation (during open water sailing, or high elevation trekking), strokes or other disruptions of blood flow to the brain, and, possibly, in pathological conditions such as schizophrenia.
Well, now we have a nice scientific explanation of a range of formerly paranormal phenomena. The explanation is consistent with what we know of human neurobiology and psychology, it is testable and repeatable under laboratory conditions, and accounts also for non-paranormal phenomena such as phantom limbs. Case closed, right? Yeah, right...