Is your brain in pain?

OK, focus: How much of your brain are you using up right now – or at all times?

If you said 10%, you repeated a popular myth, but it was incorrect.

The origin of the tale is murky but could be rooted in an outdated theory about the structure of the brain that was repeated in a best-selling self-help book over 80 years ago.

Today, the trope is still trotted in cartoons, books and movies.

In the 2014 thriller “Lucy,” a scientist repeats the 10% claim while speculating on the promise of accessing more of the mind. The 2011 film “Limitless”, about a struggling writer, rates the fraction at a slightly more encouraging 20%. And the 1991 comedy “Defending Your Life,” about a deceased man’s efforts to prove his worth in the afterlife, cuts it down at a demoralizing rate of 3% to 5%.