Someone has taken most of your brain away and you probably didn't even know it. Well, not taken your brain away, exactly, but decided that you don't use it. It's the old myth heard time and again about how people use only ten percent of their brains. While for the people who repeat that myth, it's probably true, the rest of us happily use all of our brains. One reason this myth has endured is that it has been adopted by psychics and other paranormal pushers to explain psychic powers.The argument that psychic powers come from the unused majority of the brain is based on the logical fallacy of the argument from ignorance. In this fallacy, lack of proof for a position (or simply lack of information) is used to try to support a particular claim. Even if it were true that the vast majority of the human mind is unused (which it clearly is not), that fact in no way implies that any extra capacity could somehow give people paranormal powers.What follows are two of the reasons that the Ten-Percent story is suspect.
- Brain imaging research techniques such as PET scans (positron emission tomography) and fMRI (functional magnetic resonance imaging) clearly show that the vast majority of the brain does not lie fallow. Indeed, although certain minor functions may use only a small part of the brain at one time, any sufficiently complex set of activities or thought patterns will indeed use many parts of the brain. Just as people don't use all of their muscle groups at one time, they also don't use all of their brain at once. For any given activity, such as eating, watching television, making love, or reading Skeptical Inquirer, you may use a few specific parts of your brain. Over the course of a whole day, however, just about all of the brain is used at one time or another.
- The myth presupposes an extreme localization of functions in the brain. If the "used" or "necessary" parts of the brain were scattered all around the organ, that would imply that much of the brain is in fact necessary. But the myth implies that the "used" part of the brain is a discrete area, and the "unused" part is like an appendix or tonsil, taking up space but essentially unnecessary. But if all those parts of the brain are unused, removal or damage to the "unused" part of the brain should be minor or unnoticed. Yet people who have suffered head trauma, a stroke, or other brain injury are frequently severely impaired. Have you ever heard a doctor say, ". . . But luckily when that bullet entered his skull, it only damaged the 90 percent of his brain he didn't use"? Of course not.