Do We Really Only Use 10% of Our Brains?

Q: Dear Iron Shrink,

Every once in a while I hear someone say “we only use 10% of our brain.” In the movie “The Secret,” they say we only use 5% of our brain. I don’t believe it. Where did this come from?

- Secret Identity

A: Dear SI,

The idea that we only use 10% of our brains is alluring. Why, just imagine what we could do if we somehow switched on the other 90%. Telekinesis! Mind reading! Time travel! Forging an army of zombie slaves! Who wouldn’t trade their crystal balls for powers like those?

Sadly, the myth has been pretty thoroughly debunked. It is true that, at any given time, we only use portions of our brains. Brain imaging bears this out. But that doesn’t mean that we have vast, untapped reserves of psychic abilities.

The most apt analogy is muscle. We don’t use our entire brain at once any more than we use all of our muscles at once. But follow someone around for a day or two, and eventually they will use just about every muscle and every part of the brain – the good folks at the DMV notwithstanding.

The 10% myth appears to stem from the work of William James, an influential American psychologist during the late 1800s. One of his contributions is the James-Lange theory of emotion, which states that emotions originate in the body rather than the mind (I’m scared because I’m running). James also believed that truth depends on its usefulness to the believer, which was a fairly stark departure from the typical American mindset at the time (the truth is the truth, dagnabbit). His contributions are still hotly debated. Well... maybe “hotly” is too strong. But they’re still debated.

One of James’ minor contributions was the brief book titled On Vital Reserves. He was curious about physical and mental limitations, and he was particularly curious about the “second wind” experience. James noticed that when exerting energy,

“The fatigue gets worse up to a certain critical point, when gradually or suddenly it passes away and we are fresher than before. We have evidently tapped a level of new energy masked until then by the fatigue-obstacle...” (p. 4).

He thought it would be useful to know how to tap that energy more easily:

“For many years I have mused on the phenomenon of second wind, trying to find a physiological theory. [James was also a doctor of medicine.] It is evident that our organism has stored-up reserves of energy that are ordinarily not called upon.”

(He would have been impressed by a buddy of mine back on the loading dock. It was hard work, and that guy had an endless supply of wind, if you know what I mean.)

James took the “second wind” experience as evidence that we don’t need to give up when we’re tired. However, he laments, too many of us do. And here’s the fateful quote:

“Stating the thing broadly, the human individual thus lives usually far within his limits; he possesses powers of various sorts which he habitually fails to use. He energizes below his maximum, and behaves below his optimum” (p. 12).

Clearly, William James was writing about initiative and discipline. Don’t give up, he said, “the busiest man need no more rest than the idler.” 100 years and 1,000 self-help gurus later, that idea has morphed into the promise of amazing psychic abilities.

Those gurus are making a common logical error: the absence of evidence against psychic abilities is taken as evidence in favor of them. Combine that error with images of mostly dormant looking brains (just as most of your muscles are inactive as you read this), and the lure of psychic abilities is awfully darned tempting.

But let’s not make a similar mistake in reverse. While we don’t possess hard evidence of paranormal abilities, that doesn’t mean they don’t exist. If it serves you to pursue them, William James might want you to keep on trying.

-IS

References:
James, W. (1899). On Vital Reserves. New York: Henry Holt and Co.

My gratitude to the Special Collections staff at the University of Denver’s Penrose Library.