The 10% myth

Albert Einstein claimed that we only use 10% of our brains and that through accessing more than this he was able to be successful and achieve what he did. Imagine if you could access more than 10% of your own brain… There has been much interest in this area in advertising, with this fact often stated on the cover of magazines and in adverts. It is also frequently quoted in New Age material, attempting to convince you to try a new technique or to buy a new product. There have also been movies made on this topic, such as Limitless with Bradley Cooper that I personally was quite a fan of, and Lucy with Scarlett Johannsen. These movies show the potential available in your brain if you can just unlock the latent potential present, although in the case of Lucy maybe not to that extreme (such as time travel and ascendance to a higher plane).

The problem is … none of that is true (other than the movies being made). Albert Einstein never claimed anything of the sort. In fact, use that as a warning to always check sources before quoting facts others have stated. The claims that we only use 10% of our brains predate him, dating back to at least the 1929 World Almanac which stated “There is no limit to what the human brain can accomplish. Scientists & psychologists tell us we use only about 10% of our brain power.” This has been a common claim since at least that time in self-help materials. Most prominently, Lowell Thomas, in the foreword to How to Win Friends and Influence People (by Dale Carnegie), “quoting” William James, incorrectly stated that we only meet about 10% of our full mental potential. In truth, William James had said that we only meet a fraction of our full mental potential, never stating any percentage. Our “full mental potential” is a different topic to how much of our brain power we use at any given time, but it is the latter that is frequently claimed.

Brain Injuries

If we truly only use 10% of our brain, then that would mean that 90% of our brain is superfluous. In that case, why is it that practically every brain injury results in some sort of loss of ability for the patient? If 90% of the brain is unused, the majority of brain injuries (at least those of a small nature) should result in no noticeable effect to the patient? In contrast, even the slightest of injuries to the smallest of areas result in noticeable and profound effects.

What to remove?

Further, if we have 90% of our brain being superfluous, why don’t we remove the spare 90% and use that space for something else, such as installing a computer in order to become a cyborg and enhance our potential. What should we remove to make space then?


What about the cerebellum? The word cerebellum is Latin, and is derived from the word cerebrum, meaning brain, and the suffix -ellum, meaning the diminutive form. It literally means little brain. As such, the cerebellum is like a small brain that sits beneath the back of the brain, behind the brain stem, and accounts for roughly 10% of the brain mass by itself. It is responsible for refining movement and is heavily involved with coordination, receiving proprioceptive information from across the body and incorporating this into modifying muscle signals that the brain sends. Proprioceptive sensation is the sensation of where your body parts are within space, so that even if your eyes are closed or you can’t see the body part you know where it is, such as when your arm is behind your back, when you’re typing on a keyboard while looking at the screen, or when you’re walking and looking ahead of you. Incorporation of this, combined with the dampening of the gross signals sent by the cortex, makes movement useful.

When the cerebellum is absent, such as in the congenital case of Dandy-Walker malformation, a loss of coordination is seen. This loss of coordination is seen in gait (the way that a person walks and stands, effectively their posture and movement), it is seen in their eye movements (such as uncoordinated or disconjugate eye movement, where the eyes don’t move together), and it is seen in their speech (such as difficulty pronouncing phrases or sounds, or pausing at the start of each syllable). A similar pattern is seen in inherited conditions, such as in the autosomal recessive Friedrich Ataxia and in the autosomal dominant Spinocerebellar ataxia.


Ok, not the cerebellum then, what about the cerebrum? That makes up 85% of brain mass, we should be able to find some waste there… Of the 85% of brain mass that the cerebrum makes up, roughly 40% contributes to the grey matter. The grey matter is primarily the actual neural cells that produce “thought”, and are basically divided into four sections called lobes. These are the frontal lobe, parietal lobe, occipital lobe, and temporal lobe. The frontal lobe is responsible for muscle movement, for short term memory, for thinking, for decision making, and for planning. Probably not the best idea to remove those functions. The parietal lobe is responsible for receiving and processing sensory information, maybe we will keep that. The occipital lobe is responsible for visual information (among other things), and we sure don’t want to be blind. The temporal lobe is responsible for auditory information, for long-term memory formation, and for language and speech production. This seems harder than we thought.

Wait up, that was less than half of the cerebrum. What about the rest? The majority of the weight of the cerebrum is made up of the white matter and the basal ganglia. The white matter is mostly made up of tracts (that allow the brain to communicate with the rest of the body) and glial support cells. If these tracts were removed, the brain would not be able to receive sensory information from the body, and it would not be able to send signals (such as movement) to the rest of the body. These are reasonably heavy as they are covered in what are known as myelin sheaths, similar to insulation on cables, which allow the messages to be both faster and more accurate when they reach their destination. The glial cells perform many functions to support the brain, including the production of the myelin sheaths just mentioned.

The basal ganglia contains numerous structures that mostly regulate skeletal muscle movement (i.e., voluntary muscle movement), but I’ll speak mainly of two of them. The caudate nucleus is the main GABAergic area within the brain, meaning it plays a major role in inhibiting actions. If you remove the caudate nucleus, you wind up with Huntington’s disease, which results from the degeneration of the caudate nucleus. Alternatively, the substantia nigra is the portion of the basal ganglia that is primarily responsible for initiating movement. Degeneration of this region of the basal ganglia results in Parkinson’s Disorder, which involves significant difficulty in getting moving.

Other structures

Illustration from Anatomy & Physiology, Connexions Web site., Jun 19, 2013.

The remaining major structures within the brain are the diencephalon and the brain stem. The diencephalon contains many structures, each with their own regulatory functions, including the thalamus, hypothalamus, pituitary gland, pineal gland, mamillary body, and more. The brain stem controls automatic behaviours, such as breathing. Think about how you’re currently breathing and how you have been for the whole time you’ve been reading this article without thinking about it. Your breathing is controlled primarily in four locations, all within the brain stem (see image). Within the medulla oblongata are the regions responsible for inspiration (breathing in) and expiration (breathing out), the dorsal respiratory group and ventral respiratory group respectively. Within the pons are located the pneumotaxic centre, which regulates the rate and pattern of breathing, and the apneustic centre, which among other things stimulates the dorsal respiratory group and inhibits the ventral respiratory group to allow for inspiration.

How could it occur?

Ok, fine, so there’s no part of your brain that seems to be unnecessary. But, it doesn’t even make sense that the brain would be larger than it is required to be. Why would an all-knowing, all-powerful God create a brain that is larger than it is required to be? If God made us in his image, why would He burden us with such an obvious flaw and waste of potential?

Personally, I’m an atheist, so I don’t actually believe that God created us. But, that just shifts the question, and makes it even more obviously flawed: Why would evolution create an organism with an organ that was incredibly inefficient? Despite only making up around 2% of the bodies mass, the brain consumes around 20% of the oxygen and resources that the body takes in. If 90% of the brain was unnecessary, natural selection would select for more efficient brains of a smaller size with lower demands. It wouldn’t even make sense for natural selection to create this situation in the first place. Before modern medicine, there was (and to be fair, still can be) a significant historical risk of death in childbirth to both the child and mother due to the large brain size. The large brain size creates the need for a large skull size, which causes major difficulties with birthing through the limited space in the pelvis and vaginal canal. To compensate, birthing occurs while the newborn is still underdeveloped and this in itself creates major demands on the parents for resources and protection for a long time post-partum.

The evidence doesn’t agree

Finally, the scientific evidence has for a very long time shown that this claim isn’t the case. Decades of research have gone into mapping the functions of the regions of the brain, and this has found that the brain has distinct regions for different kinds of information processing. Further, there has not been a single function-less area discovered within the brain. Even since the development of single unit recording techniques, which are tiny electrodes that can monitor single brain cells, no unused cells have been discovered, which would be incredibly unlikely if the majority (or even a noticeable portion) of the brain was not used.

They have also found that all of the areas of your brain are always active, even when you’re asleep! Through technology such as functional MRI’s, it has been shown that regions all across the brain are active, regardless of the task that is being performed by the participant. At any given time, and depending on the task that’s being performed, some areas are more active than others. But, they’re all still active during those tasks.

Regardless of all of the above, cells that are unused atrophy (decrease in size or degenerate). This also occurs with underused neural cells. Despite this, autopsies have not shown the large-scale degeneration that would be expected if 90% of the brain was frequently unused.

Using your whole brain

So, I guess, congratulations! After reading this blog post, you’re now successfully using more than 10% of your brain, just as Einstein did. In fact, you always have been using more than 10% of your brain. Most of us may never achieve our full mental potential, and that is something to strive for, through challenging and pushing ourselves to new heights. But, your brain’s mass is being utilised fine. You don’t even want to be using your whole brain at the same time, as doing so would almost certainly trigger an epileptic seizure. In fact, this is what is seen on an EEG (electroencephalogram) during an epileptic seizure. But, you’re at least using your whole brain and not wasting any of it across any given day either way!

This Post Has 8 Comments

  1. This is a very interesting blog which has completely changed my belief of how much of our brains we are using. How many times have we heard that comment that we are only using 10% of our brain and we are happy to believe it without thinking about it? Thank you Adrian for your questioning mind. You have taught me a lesson.

    1. Thank you for your comment.
      Yes, I agree that so often it is easy to take for granted what we hear all the time. It is just unfortunate that often what is claimed and what is frequently stated don’t agree with what is actually the case. I am happy to hear about your paradigm shift as a result of this post.

  2. Good work Adrian it is not always easy to put things into simple terms that everyone can understand and you have done a great job…

    1. Thank you, Heather.

      I actually thought this one was still in too much detail, too many “scientific” words. Aiming to go even more simple for future posts. I appreciate the input though, we’ll see how I do in future :).

  3. Adrian, I enjoyed your perspective. The Brain parts and function can certainly be complex and confusing. Thanks for making your information lay-person friendly.

    1. Thank you, Alana. I definitely agree that the brain is fascinating.

      I appreciate the feedback. I was worried that I was too in detail, so appreciate your input that it is at a good level.

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    1. Hey, glad that you enjoy the website and found value in it.

      Sorry that I’m a little behind on these posts, didn’t post this week. Fly back home on New Years night, and then have had a very lazy week this first week of the year, recovering from the trip and time zone change.

      I’ll definitely have new content out on Tuesday though, continuing my Think Like a Medical Student series, and then Friday will be another non-series post. Hope you enjoy them.

      As to saving me as a favourite, if you want there is a subscribe option in the sidebar that means you’d get an e-mail when new posts go live if that’s more convenient for you.

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