Tales of the Odd: A Dose of the Unexplained

The myth's durability, Gordon says, stems from people's conceptions about their own brains: they see their own shortcomings as evidence of the existence of untapped gray matter. This is a false assumption. What is correct, however, is that at certain moments in anyone's life, such as when we are simply at rest and thinking, we may be using only 10 percent of our brains.

"It turns out though, that we use virtually every part of the brain, and that [most of] the brain is active almost all the time," Gordon adds. "Let's put it this way: the brain represents three percent of the body's weight and uses 20 percent of the body's energy."  Do People Only Use 10 Percent Of Their Brains?


What follows are two of the reasons that the Ten-Percent story is suspect. (For a much more thorough and detailed analysis of the subject, see Barry Beyerstein’s chapter in the new book Mind Myths: Exploring Everyday Mysteries of the Mind [1999].)

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. The Ten-Percent Myth