Suzana Herculano-Houzel

Do you only use 10% of your brain?


I already knew the phrase, but I decided to ask. In a survey called “Do You Know Your Brain?”, I consulted just over two thousand lay people on various subjects. Among other things, did they agree that “we normally only use 10% of our brain”? Half of them did. I then repeated the question to a few dozen neuroscientists, and they promptly disagreed. The verdict? This story about using 10% of the brain is a myth.

A myth of great appeal, it’s true. Anyone who only used 10% of their brain would have 90% to spare and, if they learned to use it, they could become 10 times smarter, remember 10 times more information, do math 10 times faster, speak 10 times more languages. You can indeed get smarter, remember more, be faster, and speak more languages – but it won’t be by using more than 10% of your brain.

As far as is known, there are no silent or “reserve” regions in the brain, and the brain is certainly not 90% reserve. Each part of the brain has its own specific function and, even if this is unknown here and there, images of the brain in operation show that all of it works and consumes energy, all the time – even while you sleep. Of course, some regions work more or less, depending on the task at hand. But all of them are active, ready to go, and all of them have their role to play. So you don’t need to lose 90% of your brain to suffer serious consequences. Lose the equivalent of a thimble in the right place and, for example, you could be deprived of speech or sight.

It’s also a mistake to believe that you only use 10% of your “brain capacity”. Just remember that in order to calculate the use of that 10%, you would need to know the limit, the 100% of that capacity. Who would this reference be who uses 100% of their “brain capacity”? To all appearances, it wouldn’t be a genius, but an unfortunate person who couldn’t learn anything else.

In fact, reader, you already use 100% of your brain. You use both your right and left hemispheres, you use all the structures, you have all the neurons that are capable and functional. And yet you can still push yourself and learn new things every day, speak new languages, become a painter, a fencer or a dressmaker. The reason? What makes the difference is not how much of your brain you use, but how you use it: what you demand of your brain, how you treat it, what information you offer it, how you explore and combine it. So don’t worry about using more of your brain, because you already use 100% of it. Instead, worry about using it better!

Originally published in Folha de São Paulo on May 1st, 2006. 

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