In the film, the drugs implanted into Lucy (played by Scarlett Johansson) leak into her system, allowing her to “access 100 per cent” of her brain. Among other things, Lucy can move objects with her mind, choose not to feel pain and memorize copious amounts of information. In a way, the idea that we only use 10 per cent of our brains is rather inspiring. It may motivate us to try harder or to tap into some mysterious, intact reservoir of creativity and potential. There are even products that promise to unlock that other 90 per cent.
As ludicrous as the claim is, however, two-thirds of the public and, get this, half of science teachers reportedly still believe the myth to be true. The notion is so widespread that when University College London neuroscientist Sophie Scott attended a first aid course, her instructor assured the class that head injuries weren’t dangerous because “90 per cent of the brain (doesn’t) do anything.”
Here’s the thing: The brain has rapidly tripled its original size across two million years of human evolution. Despite only accounting for 2 per cent of our body weight, the brain gobbles up a whopping 20 per cent of our daily energy intake. Our brains are also remarkably efficient, having evolved gyri (ridges), which have dramatically increased our cortical-surface-area-to-total-volume ratio relative to other species. The “we only use 10 per cent of our brains” claim would mean that we’re effectively evolving in the opposite direction — and that we’re doing this very quickly.
Another obvious way we know that we’re using more than 10 per cent of our brain at any one time is through approaches like functional magnetic resonance imaging and positron emission tomography. PET and fMRI are imaging techniques that reveal areas of relatively high brain activity in real time. Imaging studies tell us that not only are many brain areas recruited when performing even the simplest of tasks, like watching a movie, but that the activity between these areas is extremely dynamic.