Do we use only 10% of our brain?

This post is also available in Dutch.

The idea that humans use only 10% of their brains is very popular. But is it true? And where did this theory originate? Erik Meijs takes a look.

LoadingDo we only use 10% of our brain? This is probably the most well-known folk idea about the brain. Nobody really knows what the source of this statistic is, but it may have originated in a time when people simply did not know what the roles of most brain areas were. The 10% story sounds appealing because it suggests that we could unlock extra potential or increase our intelligence if we could just use a larger percentage of our brain. This idea is so alluring that it has been used as the premise for all kinds of stories in popular culture, like the movie Unstoppable.

You only use 10% of your brain
The most common version of the 10% story suggests that during your entire life you only use 10% of your brain. As you may have expected, this is complete nonsense. A quick look at neuroscience shows that every part of the brain is involved in at least one function. Even during rest or sleep, there is activity throughout the brain.

Moreover, the brain operates under a sort of ‘use it or lose it’ rule: parts of the brain (for example neurons or connections between neurons) that are not used are removed (‘pruned’). Other evidence against the 10% myth comes from patients with brain lesions. Even though some patients can live relatively normal lives, basically every type of brain lesion leads to some problems. Finally, it is unlikely that humans evolved to have a large brain that requires a lot of energy and yet is barely used.

You only use 10% of your brain at any moment
Now that we have established that it is a myth that 90% of your brain does nothing at all, you may still wonder how much of your brain you use at any given moment in time. Well, the brain constantly works on keeping its internal balance of molecules in check to ensure it is always ready to respond to incoming information. In that sense, all of the brain is active all the time.

Still, this type of background processing is likely not what you had in mind when you asked how much of the brain we use at any moment. Probably, you want to know how much of the brain is ‘used’ (whatever that means), on average, to complete a certain action. For example, you may wonder whether you actually ‘need’ 100% of your brain to read and understand this article.

The answer to that question is most likely no. We know that some patients with damage to a limited part of the brain can still perform certain tasks without problems. But there is no easy and complete answer to the question ‘how much of the brain is strictly necessary to lead a normal life?’ If there were any realistic way of answering that question, it would probably require 200% of your time.

Erik Meijs is a PhD student in the Prediction & Attention group at the Donders Institute. His research focuses on how our expectations affect what we perceive (un)consciously. In his spare time, Erik likes to travel and to make music or listen to it.

Edited by Jeroen.

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