For as long as I can remember I’ve heard this as a fact. I think this myth persists because it allows people to think: “If I’m only using 10% of my brain, imagine how smart I’d be if I could use the other 90%!” And, like many learning myths, it is part of popular culture as received wisdom. It was even the plot of a 2014 movie, “Lucy,” in which Scarlett Johannson develops the superhuman power to use 100% of her brain.
So, where did this myth come from? In 1908 the psychologist William James wrote (with no evidence at all) that “We are making use of only a small part of our possible mental and physical resources.” And, there is apparently a (mis) quote from Albert Einstein about using more of his brain than others.
But now we have fMRI equipment and we can actually “see” what is going on inside the brain. It turns out that we do use all of our brains — and even when we are “resting” the brain is still active. In fact, the brain, while only 3% of our body weight, uses 20% of the body’s energy.
It is true that at any particular moment we are not using all of our brain, but in any given 24-hour period we do, in fact, use 100% of it.