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The 10 Percent Brain Myth

Oct. 17, 2015 by | Comments (12)

This is an excerpt from Junior Skeptic 37 (published in 2010 inside Skeptic magazine Vol. 15, No. 4), which is a quick ten-page tour of the “Top Ten Busted Myths.” Junior Skeptic is written for (older) children, and does not include endnotes, though I often call out important sources in sidebars or the text of the story itself. However, I’ve included one or two citations here for your interest:

Have you heard that we only use 10 percent of our brains? Imagine what we could accomplish if we could discover how to use that other 90 percent! Could we discover an untapped potential for incredible psychic powers?

There’s only one problem: none of that is true. Humans use every part of our brains.

Everyone has heard the 10 percent myth, and many people believe it. Why wouldn’t they? We hear this fake “fact” very often in movies1 and TV. As neurologist Steven Novella explains, most people “accept this as just another amazing but true pronouncement of science without too much scrutiny.” It doesn’t occur to most people to ask, “Is this true?” or, “Why would we evolve over-sized brains if we didn’t actually use them?”

For more of Junior Skeptic‘s “Top 10 Busted Myths,” see issue 37 (published in 2010 inside Skeptic Vol. 15, No. 4).

There’s plenty more to learn about the complex human brain, but scientists have been studying it for a long time. One thing they’ve learned is that we lose specific brain functions if specific parts of the brain get damaged by disease or injury. For example, damage to a certain spot in the brain might take away a patient’s ability to speak, while leaving other abilities intact. Damage to other spots might take away a patient’s ability to remember faces, or count, or so on. Studying such specific brain injuries has allowed scientists to map out the jobs of the various parts of the brain. “Today the entire brain is mapped in extensive detail,” explains Dr. Novella, “and a specific function has been found for each part of the brain.”2

Modern scientists can use sophisticated scanning machines to see which parts of the brain are active. Brain scans clearly show that we use our entire brain in our day to day lives.

Even if we didn’t know for a fact that we use our whole brain, we could guess it simply because our brains use up so much energy. Even though brains are just a small part of our bodies, they use a fifth of our bodies’ food and oxygen.3 If we didn’t use our brains, we wouldn’t have evolved something so “expensive” to fuel up.

It’s easy to understand why people would believe a fake fact that they hear often—most of us are not scientific experts. But if the 10 percent brain myth is so wildly wrong, how did the idea get started in the first place?

The answer is that no one knows the answer. Folks have been passing the myth around for about 100 years, but it’s not clear how it got started. Steven Novella suggests that it could be a misunderstanding from early in the history of brain research. When scientists said they still needed to map the specific functions of most parts of the brain, this might have been misunderstood. Perhaps some people thought this meant most of the brain had no function?

However it started, one thing is certain: the 10 percent brain myth is 100 percent bogus.

  1. A notable example is the 2014 Luc Besson film Lucy starring Scarlett Johansson. The plot involves a woman who comes to “access 100 percent” of her brain and as a result gains godlike powers.
  2. Steven Novella. “90% of a Brain Is a Terrible Thing To Waste.” January 1999.
  3. Ibid.
Daniel Loxton

Daniel Loxton is the Editor of INSIGHT at and of Junior Skeptic, the 10-page kids’ science section bound within Skeptic magazine. Daniel has been an avid follower of the paranormal literature since childhood, and of the skeptical literature since his youth. He is also an award-winning author. Read Daniel’s full bio or his other posts on this blog.

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