Do We Really Use Only 10% of Our Brains?

“Humans use only 10% of their brains. Awaken the rest, and you’ll gain astonishing abilities.” It’s a staple of movie plots and an old line in ads for study methods. It’s an appealing story, but also one of the misconceptions neuroscientists correct most often.

The brain can’t afford to leave parts idle

The adult brain makes up only about 2% of body weight, yet it consumes about 20% of the energy the body uses at rest (Raichle & Gusnard, 2002). From an evolutionary point of view, there would be no reason to maintain, at such a high cost, an organ that leaves 90% of itself idle.

Brain imaging tells the same story. When the brain is scanned with functional MRI or PET, almost every region is busy at some point as we go about our day. It is true that not every region runs at full capacity at the same moment, but that isn’t “not using” them; it is selecting the circuits that are needed. A state in which every region fires strongly at once is closer to a seizure. And the fact that damage to even a very small part of the brain can cause clear problems with language, movement, or memory is strong evidence that the brain has no “spare 90%.”

A fact more amazing than the myth: the brain changes as you use it

The 10% myth being wrong doesn’t mean the brain’s potential is fixed. With experience and repetition, the brain strengthens or weakens its connections, and sometimes its very structure changes. This is called neuroplasticity.

A classic example is the study of London taxi drivers. To get a taxi license in London, drivers have to memorize a vast number of streets across a complicated city. When researchers scanned the brains of experienced taxi drivers, the back of the hippocampus, which is involved in spatial navigation, was larger than in a comparison group, and the longer someone had been driving, the larger it was (Maguire et al., 2000). The study showed that experience can be linked to the structure of the brain.

What should we take from the myth?

The 10% myth has probably survived so long because the belief that “I still have untapped potential” moves people. That belief itself isn’t wrong. But there is no secret technique to “awaken” a hidden 90%; potential becomes real through the way repeated practice and experience rewire circuits. That’s also why this site is called “The Game of Belief, Action.”

Today’s practice

1. Be skeptical of ads promising to “unlock your brain’s potential.” Claims that a particular drink, sound, or gadget awakens a hidden part of the brain usually have no evidence behind them.
2. Choose one new skill and practice it briefly every day. Plasticity depends more on repetition and consistency than on intensity.
3. Practice at a slightly harder level. Rather than repeating only what is already easy, staying at a level that is a little too hard gives the brain more reason to change.
4. Take care of sleep and exercise, too. Our other articles on memory consolidation and the health of the hippocampus support this practice.

References

• Raichle, M. E., & Gusnard, D. A. (2002). Appraising the brain’s energy budget. Proceedings of the National Academy of Sciences, 99(16), 10237–10239.
• Maguire, E. A. et al. (2000). Navigation-related structural change in the hippocampi of taxi drivers. Proceedings of the National Academy of Sciences, 97(8), 4398–4403.