You've heard it since you were a child, and it might have even crept into one of your textbooks: "We only use 10% of our brain! Just think what we'd be capable of if we could tap into the rest!"
The idea that the brain has UNLIMITED POTENTIAL is probably pretty appealing to 2nd grade teachers whose students complain that they can't do ONE MORE math problem. We still remember our teachers happily informing us that we're only using 10% of our brains, so we could do ten more if we wanted. The implication was of course that if we worked hard enough, we'd be able to set fire to the school with the power of our minds.
Why Is It a Load of Crap?
How fast are you reading this article? Well, let's suppose you are only using 10% of your brain. Now, read it 10x faster. Go, do it now! Are you having trouble? Yeah, that's because you can't devote that other 90% to just whatever you want. The parts of the brain are specialized, so trying to use all of it at once isn't going to make you any smarter. That would be like trying to become a better writer by striving to use all the keys on your keyboard in every sentence.
So the part of your brain you're using to read this article is not the same part you'll be using tonight when you get drunk and fight a hobo. There's even a special part of the brain that apparently keeps you from turning into a dick (No, really).
Who Started It?
There is a bit of debate on who exactly brought this bullshit statistic into the world. A series of neurologists over the past few hundred years figured out that a human can survive when parts of the brain are removed. Over time, this was misinterpreted to mean that the brain uses little of its potential, and thus the 10% statistic was born.
Facts tend to survive based on how interesting they are, rather than whether or not they're true.
Who Was Fooled?
Surely nobody takes this seriously any more, not when a ten-second Google search can tell you otherwise, right? Well don't tell that to Psychology Today, who ran that helpful 2006 article on how to access the lazy 90% of your grey matter.