Understanding the human brain may be the most difficult challenge of them all because we're asking the brain to understand itself. The more you think about it, the more convoluted it seems. Self-understanding never comes easy!

Take, for example, the brain myths that persist in pop culture, like the left-brain, right-brain myth. Perhaps the most popular — and the most exasperating to neuroscientists — is the 10% brain myth.

Untapped Superpowers

Hollywood loves the theory that we only use 10% of our brain, and it is easy to understand why. One of the more recent depictions of this theory came in the 2014 Scarlett Johansson film "Lucy." When Johansson's character got a brain boost to 100%, not only could she learn Chinese in an instant and beat up the bad guys, she could also throw cars with her mind, says WIRED. How awesome is that?

Hollywood has been exploring the notion that we're only using small parts of the human brain for decades, with WIRED taking note of "Flight of the Navigator" (1986), "Defending Your Life" (1991), and more recently 2011's "Limitless," while Psychology Today adds the 1996 film "Phenomenon" to the list.

Hollywood loves stories about superpowers, especially when any ordinary person might have them. But really, we love it. Who wouldn't want to suddenly become a genius who can also throw cars with their mind?

Nagging Little Doubts

Sadly, we have to throw a little cold water on the 10% brain myth. And we can't even pick up the water glass with our minds.

The first little doubt we might have is that even if the myth were true, how would we know? The only way to prove it would be to find someone who uses their whole brain — and shows it by being 10 times as smart as everyone else. To be sure, some people are exceptionally sharp, but 10 times normal? What would that even mean?

As Scientific America n points out, there are other facts about the brain that cast doubt on one of the most popular brain myths. The parts of the human brain are a product of natural selection, which would not evolve capabilities that are never used. Psychology Today expands on this point: One of the basic facts about the brain is that it uses about 20% of the body's energy — which would mean an awful lot of energy going to waste if the brain were always so underutilized.

Evolution of a Myth

So where did the 10% brain myth come from? Its roots seem to go back a century or more, to pioneering psychologist William James. As Scientific American recounts, alongside his scholarly work, James wrote extensively for the popular audience of his day, and often stated that most people only achieved a small fraction of their potential.

For example, reports Nature, in 1907 he wrote that "we are making use of only a small part of our possible mental and physical resources." But he never said 10%, or gave any other specific figure; nor did he say that this was due to only using a fraction of the brain. (As opposed to, say, either insufficient effort or misdirected efforts).

But self-help gurus are not a 21st century invention, and according to Psychology Today a self-help ad was promoting the 10% myth as early as 1929. The myth got a big boost in 1936, adds Scientific American, when an introduction to Dale Carnegie's immensely popular self-help book "How to Win Friends and Influence People" included the 10% figure, attributing it to William James.

The 10% estimate may also have been reinforced, according to Psychology Today, by brain probe research pioneer Wilder Graves Penfield, who found that only about 10% of his probe tests produced a direct response (such as wiggling a toe). Penfield never said that the other 90% of the brain was doing nothing, only that it didn't respond to probes in any obvious, direct way.

So don't expect any new miracle drug or brain surgery technique to turn you into a super genius, much less allow your brain to give cars a toss. But examining myths, and how they arise and persist, is one more way that the brain can indeed study itself.