Summer action flicks are oft-described as best enjoyed with your brain off, a premise that's the complete opposite of what Scarlett Johansson's character experiences in "Lucy." The new film by celebrated sci-fi director Luc Besson revolves around the idea that humans are only capable of using 10 percent of their brain capacity. When Johansson's down-on-her-luck Lucy ingests a drug that unlocks the other 90 percent, the secrets of the universe are basically at her disposal.

Since we've all likely heard about the 10 percent rule, it's a cool dream to think that there's some inner-superhero inside us just waiting to be released. Unfortunately, the idea that humans only use 10 percent of their brains is as much a piece of fiction as Lucy's new abilities to control time and space.

"... the brain, like all our other organs, has been shaped by natural selection," Barry L. Beyerstein of the Brain Behavior Laboratory at Simon Fraser University told Scientific American. "Brain tissue is metabolically expensive both to grow and to run, and it strains credulity to think that evolution would have permitted squandering of resources on a scale necessary to build and maintain such a massively underutilized organ. Moreover, doubts are fueled by ample evidence from clinical neurology. Losing far less than 90 percent of the brain to accident or disease has catastrophic consequences."

Indeed, brain imaging technology has revealed that even during sleep, all parts of the brain show some level of activity.

Besson, who admits the 10 percent rule is a myth, nevertheless was determined to add some amount of truth to "Lucy," consulting professors of neuroscience on what might happen if our cognitive abilities dramatically increased.

"The 10 percent is a metaphor in a way," he told Vulture. "So that’s why I was not bothered by that. I’m always amazed by these people who become scientists at the last minute and go, “This is wrong!” Of course; it’s a film. [Laughs.] What’s more interesting — more than the 10 percent or the 15 percent — is that if we get the capacity of full intelligence, in the film, we say that the first step is the control of the cell, the second step is the control of others, the third is the control of matter, and the fourth is the control of time. And I talked to a lot of scientists, and they believe that at least the first three are possible. They don’t say it’s true, but it’s at least logical."

"Lucy" currently stands at a mixed 63 percent approval rating with critics. Check out the trailer below.

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Michael d'Estries ( @michaeldestries ) covers science, technology, art, and the beautiful, unusual corners of our incredible world.

'Lucy' and the 10 percent brain myth
New action flick starring Scarlett Johansson hinges on the bad science that humans only use a a small percent of their brain capacity.