I’ve written here before about how scientists have thoroughly debunked that old pop-psychology assertion that individual differences in cognitive (thinking) style are because people are either “right-brained” (creative) or “left-brained”(analytical).
For example, a 2013 study, in which the brain scans of more than 1,000 participants were carefully analyzed, found absolutely no evidence that individuals demonstrate a preference for one hemisphere over another.
Another popular — and stubbornly persistent — brain-related myth is the idea that humans use only about 10 percent of their brain’s capacity.
As McDougle points out, the 10 percent figure is “100 percent bogus.” In fact, it never had a scientific basis, but was likely “plucked out of the sky,” he says, by the American broadcast-journalist Lowell Thomas, who included it in his preface to Dale Carnegie‘s best-selling 1936 self-help book, “How to Win Friends and Influence People.”
Yet, almost 80 years later, the myth persists. Just last year, a survey conducted for the Michael J. Fox Foundation found that 65 percent of Americans believe it to be true.
And it’s likely to become even more ingrained into popular thinking this year, thanks to the premise of the new sci-fi thriller “Lucy.” In the trailer for that film, Morgan Freeman, playing a professor of neuroscience, is featured (rather ominously) making this statement: “It is estimated most human beings only use 10 percent of the brain’s capacity. Imagine if we could access 100 percent. Interesting things begin to happen.”
Well, if the trailer is any guide, very interesting things begin to happen to Scarlet Johansson.
What the science shows
Go ahead and enjoy the movie, but don’t believe that 10 percent claim. For it’s wrong on many levels, as McDougle explains:
First, the entire brain is active all the time. The brain is an organ. Its living neurons, and the cells that support them, are always doing something. (Where’s the “you only use 10 percent of your spleen” myth?) Joe LeDoux, a professor of neuroscience and psychology at [New York University], thinks that people today may be thrown off by the “blobs” — the dispersed markers of high brain activity — seen in functional magnetic resonance imaging (fMRI) of the human brain. These blobs are often what people are talking about when they refer to the brain “lighting up.”
Say you’re watching a movie in an fMRI scanner. Certain areas of your brain — the auditory and visual cortices, for instance — will be significantly more active than others; and that activity will show up as colored splotches when the fMRI images are later analyzed. These blobs of significant activity usually cover small portions of the brain image, often less than 10 percent, which could make it seem, to the casual observer, that the rest of the brain is idling.
But, as LeDoux put it to me in an email, “the brain could be one hundred percent active during a task with only a small percentage of brain activity unique to the task.” This kind of imaging highlights big differences in regional brain activity, not everything the brain is doing.
And that’s why the 10-percent myth, compared with other fantasies, is especially pernicious.
In fact, the entire premise of only “using” a certain proportion of your brain is misguided. When your brain works on a problem — turning light that hits your retina into an image, or preparing to reach for a pint of beer, or solving an algebra problem — its effectiveness is as much a question of “where” and “when” as it is of “how much.”
Certain regions of the brain are more specialized than others to deal with certain tasks, and most behavior depends on tight temporal coordination between those regions. Your visual system helps you locate that pint of beer, and your motor system gets your hand around it.
The idea that swaths of the brain are stagnant pudding while one section does all the work is silly. The brain is a complex, constantly multi-tasking network of tissue.
If only it were so
Of course, it’s understandable why the 10-percent falsehood appeals to us.
“If we only use 10 percent of our brains, imagine how totally great life would be if we could use more,” writes McDougle. “You could dazzle Grandma and her nursing-home crew during ‘Jeopardy.’ Or, like Lucy, you could learn Chinese calligraphy in an hour. The 10-percent myth presses the same buttons as any self-help scheme that promises to make us better, faster.”
“And that’s why the 10-percent myth, compared with other fantasies, is especially pernicious,” he adds. “It has a distinct air of scientific plausibility — it’s a zippy one-liner with a nice round number, a virus with obvious vectors in pop-psychology books, easy to repeat at cocktail parties. The myth is also part of a larger way of thinking about the brain that is characterized by misleading simplifications — like the notion that the right side of the brain is creative and the left side rational. ‘Those kinds of ideas self-perpetuate,’ LeDoux told me. ‘It’s like saying dopamine is responsible for pleasure and the amygdala makes fear. Both are wrong.’
You can read McDougle’s essay on the Atlantic website.