Do Humans Only Use 10% of Their Brains?

Is it true that we only use 10% of our brains? Today we’ll take a closer look at this pervasive urban myth.

Do Humans Only Use 10% of Our Brains?

The belief holds that deep inside each of us, there is an Einsteinian genius waiting to be unleashed. If we could only gain admission to the unused 90% of our brains, time travel and interstellar space travel would soon be within our technological grasp. We could solve the great problems of the world and live in a utopian paradise. All of our current human deficiencies are due to the fact that we can only access 10% of our brains. Our destiny is that of super-humans who have not yet achieved our potential, but until then, we remain entangled in our idiocy.

Perhaps this is what many of us would like to believe, yet the belief that we only use 10% of our brain is nothing more than a widespread myth. The truth is that our brains are constantly active, even when we’re asleep or doing simple tasks. In a 2012 interview with CBS affiliate WCCO, University of Minnesota neurologist Dr. Michael Howell commented on the oft repeated urban legend, “This is a myth that does not go away,” he said, “You’re using far more than that. Maybe not all of it, but the vast majority of it.”

It has been suggested that if we were only using 10% of our brains, we would be near death or in a coma. Even when a small area of the brain is damaged, such as in a stroke, the consequences can be disastrous to an individual’s behavior and abilities.

Dispelling the 10% Brain Myth

Using a functional magnetic resonance imaging (fMRI) scanner, which detects changes in blood flow, scientists are able to monitor neuronal activity and blood flow within the brain. Even when asleep, or doing simple tasks such as clenching the fist or moving fingers, fMRI tests have shown that the brain is almost always active and using more than 10% of it’s neural circuitry.

“When recordings are made from brain EEGs, or PET scans, or any type of brain scan, there’s no part of the brain just sitting there unused,” said director of the Center of Sensorimotor Neural Engineering at the University of Washington, Dr. Eric Chudler.

Other knowledgeable scientists unanimously disagree with the 10% brain myth, and point out the high maintenance demands of the brain on the body as additional evidence against the widely distributed untruth. In a 2008 Scientific American article, Dr. Barry Gordon, a neurologist at John Hopkins School of Medicine, made the following comment:

“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… 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.”

“That’s why the brain is such an expensive organ,” commented Dr. Chudler, “It requires 20 percent of our blood supply, and it’s a real energy hog… Besides, why would our brains have gotten bigger through evolution if so much of it were going unused?”

Below is a 5 minute “TED-ed” video by Dr. Richard E. Cytowic on the 10% brain myth:

Possible Origins of the 10% Brain Myth

Although the origination of the myth remains unknown, wide speculation has provided a list of possible origins.

• Psychologist William James is often cited in relation to this myth. In a quote that may be generally misunderstand due to being taken out of context, James wrote “We are making use of only a small part of our possible mental and physical resources” in his 1908 book entitled The Energies of Men.
• Some claim the myth originated from an Einstein quote. However, a 2012 article by the BBC states that a cognitive neuroscientist by the name of Sergio Della Sala attempted to locate the quote, yet employees at the Albert Einstein archives could find no record of it.
• Some websites mention neuroscientist Karl Lashley in connection with the 10% brain myth. Lashley found that rodents could relearn certain tasks and successfully navigate mazes after having portions of their brains removed.
• In 1980, British pediatrician John Lorber noted that patients with hydrocephalus could function with insufficient brain tissue, yet this is likely the result of the brain’s pliable adaptability, and produces no evidence of untapped brain potential.
• Psychology Today states that the myth may have originated with the research of neurosurgeon Wilder Penfield. Penfield and his associates discovered that directly stimulating the human brain with an electrode resulted in an observable effect only 10% of the time. However, a lack of discernible effects does not indicate that the part of the brain in question is not being used.
• Although seemingly not an originator of the myth, the 10% statistic is reportedly mentioned in the preface of the 1936 edition of How to Win Friends and Influence People, the best-selling book by Dale Carnegie.
• One fact that may have fueled the myth is that only a tenth of brain cells are neuronal gray matter while 90% is white matter composed of supporting glial cells. Although this is true, there is nothing in this fact signifying an unused portion of the brain.

“Lucy” Trailer

Morgan Freeman, in the trailer (below) for the 2014 movie Lucy is heard repeating the myth. At the 1:18 mark, we hear:

“It is estimated most human beings only use 10 percent of their brains’ capacity. Imagine if we could access 100 percent…”

Mythbusters

In a 2010 episode of Mythbusters, the team took on the myth by hooking up castmember Tory Belleci to a magnetoencephalogram (MEG), which measures magnetic fields produced by the brain. As he engaged in a series of mental drills, the MEG showed that 35 percent of his brain was highly active. An MRI showed 15% of Tory’s brain active while at rest, which jumped to 30% as he told a story.

Search History

The Google Trends chart below shows a history of interest on this topic.

Bottom Line

The idea that we only use 10% of our brains is a long-standing urban legend. Brain scans have proven this to be an untrue statement, and that even simple tasks use more than a tenth of the brain’s power. The myth also does not account for the human brain’s high demands, requiring about 20% of the body’s resources. This would be a very inefficient use of energy if human beings only used 10% of their brains. There is much speculation regarding the basis of this myth, yet it is not known exactly how, when, or where it originated.

Updated February 4, 2016
Originally published June 2014