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Do We Really Only Use 10% of Our Brains?

The human mind

At least since the 1930’s, and possibly earlier, it’s been common knowledge that we human beings only use 10% (or 11%, or 12%) of our brain. Einstein even said it, so it has to be true!

Except that it isn’t true. And despite urban legend, Einstein appears never to have said anything like that–not to mention that he wasn’t doing neuroscience work anyway. This is one of those pieces of fake knowledge that gets quoted all over the place (like the one that everyone needs 8 hours of sleep a night, or that it takes 21 days to form a habit) and that gives lots of people excuses to sell lots of things, but that was never based on any meaningful evidence. Brain scans using technologies like PET (positron emission tomography) and MRI (magnetic resonance imaging) routinely show activity at differing levels all throughout the brain–even when the subject is sleeping!

The confusion may have come from early experiments in which some of the first neuroscientists delivered electric shocks to parts of the brain to see if there was any physical response. Some parts, of course, have jobs like storing memory, putting together sentences, and processing visual information, so there wouldn’t be any physical response. These were labeled parts of the “silent cortex,” meaning not that they were necessarily useless, but that they didn’t have any immediate physical effects when shocked.

(Let’s both take a minute here to silently express our gratitude that we weren’t one of those scientists’ undergrads.)

Or people might be confused by the ventricles of the brain, areas in which cerebralspinal fluid is stored, which show up dark on scans. Saying that we’re not using our entire brain because we’re not doing anything with these areas is like saying a car isn’t using its entire engine because there are no moving parts in the radiator.

If you’re interested in a more detailed debunking, there’s a handy article on By the way, is also an ideal place to go if you receive an e-mail from someone and want to know if it’s a scam or a prank.

So how much of our brain do we really use? Pretty much all of it, actually. The point isn’t to find ways to use more of our brain: we’ve evolved to make very efficient use of that tissue, thank you very much. The point is to make better use of our brains. This is why it’s so helpful to find engage our minds in different ways, with both mental and physical activity–because remember that our brains have whole areas devoted to physical activity, too, and those can weaken with time just like the non-physical areas if they’re not used regularly. Brain stimulation is like exercise for muscles: anything we don’t use becomes weaker over time, and anything we do use tends to strengthen.

I’m grateful to the authors of Mind Hacks: Tips and Tricks for Using Your Brain for some of the information in this article.

PET scan images courtesy of Reigh LeBlanc

1 Comment

1 Comment

  1. Eric  •  Apr 24, 2010 @7:22 pm

    thanks for debunking this nonsense. I’ve usually heard it stated as something more like, we’re only using 10% of our potential, obviously a more subjective statement.

    however, i do have some extra brain tissue I’m not using, and if you want it, I can mail it to you.

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