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90% of Your Brain

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"[This myth is] one of the hardiest weeds in the garden of psychology."
Donald McBurney, neuropsychologist

A situation where a character's miraculous abilities are not so much a product of "superpowers" as this being something humans in the series universe could have but are unable to access for some reason. That is, until they reach Brain Critical Mass.

This trope name comes from the oft-repeated but false assertion that humans only use 10 percent of their brains, a misquote of a foreword to Dale Carnegie's How to Win Friends and Influence People.note  In Real Life, we use all of our brains, just not all at the same time — in much the same way you don't have every electronic/mechanical item in your home running at all times; you only turn things on when you need to use them. If you ever do find yourself with every part of your brain "on" at once, congratulations, you're having a seizure!

The origin of the myth may not even have anything to do with these facts about actual brain activity. It may be a distorted version of the more plausible claim that we only use a fraction of our total mental capacity, ie. we could potentially learn things more effectively and stuff. However, even in this context, the number "10%" is completely arbitrary (in other words, a statistic Dale Carnegie likely pulled right out of his ass).

This trope was examined by the MythBusters, throwing the 10% theory right out the window when it was proven that the human brain is at least 15% active while sleeping, and even more so when awake. There is debate as to how much of our brain activity takes place on the level of conscious thought, with roughly a tenth being a common figure cited, but this is still very different from claiming our brains are 90% inactive.

And the fact is, it's nonsensical. What would be the evolutionary incentive to keep this supposedly unused 90%? It's a waste of resources, of which the brain is a significant consumer. Evolution tends to trim that kind of inefficiency.

Compare Uninhibited Muscle Power, where powers activate the unused muscle potential instead of unused brain potential. For exceeding the limitations of the body to epic effect, see Charles Atlas Superpower. Also see Pineal Weirdness, which tends to show up in similar places. Very prevalent in Science Fiction as a common trope with mentalists and ESPers. A Genius Serum may come into play to unlock this "buried potential".

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    Anime & Manga 
  • In B.Ichi, the Clowns can supposedly use 50 to 60% of their brains when activating their powers. However, this detail is only mentioned in the introduction, and the Clowns' powers don't have anything to do with using more of their brains in the end.
  • Fist of the North Star does something similar with breathing. The real secret to Kenshiro's Charles Atlas Superpower is harnessing the traditionally untapped 70% of his breathing.
  • The Stone Mask-created vampires in JoJo's Bizarre Adventure gain their power through the activation of unused parts of the brain via acupuncture. This awakens the human's evolutionary potential (with abilities like Wall Crawling, liquid eye beams, superspeed/strength, regeneration, sucking blood through their fingers, and creating zombies) and it inverts the lifeforce energy in their bodies (making them undead-like beings weak to sunlight and Ripple, the amplified essence of life). Part 2 reveals these masks were created by a group called the Pillar Men, who belonged to an entire race vulnerable to sunlight. After enhancing themselves with stone masks, they turned humans into vampires to have a more-powerful food source. They also plan to enhance themselves even further in order to become the ultimate lifeforms, ridding themselves of all weaknesses, most importantly sunlight.
  • Tohru brings this up during a conversation in Miss Kobayashi's Dragon Maid. Note that Tohru is a dragon with almost zero understanding of human biology, and she brings it up in response to seeing a magic trick. The English dub works in a Take That! against Lucy by having Tohru say that she heard about it from a "should-be-forgettable movie".
  • Naruto does this, but with the chi-like chakra instead of brainpower. Rock Lee's ace in the hole is the ability to open various chakra gates that act like dams for the stuff, with opening enough of them putting him in a Kaio-Ken-esque Super Mode. The catch is that, if a ninja opened all the gates, he would suffer from a fatal Heroic Red Ring of Death.
  • The foundation of superpowers in NEEDLESS.
  • Night Head Genesis states at the start that normal people leave 70% of their brain unused. Once again, this explains Psychic Powers.
  • This is part of the premise for Psyren. Like many others, this explains Psychic Powers, though they seem no less limited than any other set of superpowers in other series.
  • In Reborn! (2004), Reborn gives Gokudera an unique brand of Training from Hell by making him eat ramen while withstanding I-pin's Gyoza-ken. Reborn's technical explanation is that, since the Gyoza-ken affects directly the brain, the fact of being able to eat ramen while resisting the muscular spasms the technique provokes would force Gokudera to use all of his brain capacity (whose standard usage is defined here as 30%).
  • Referenced and subverted in Uncle from Another World: Uncle (having grown up in the nineties) believes this trope is true, and that unlocking it was the source of the power he obtained in the other world. Takafumi (having grown up in the twenty-tens and with easy access to the internet) immediately points out the trope was debunked long ago.

    Comic Books 
  • In Archie Comics, Archie recites this statistic to his friends. Moose exclaims that 10% is "almost less than half our brains". Archie muses that the statistic is too high in some cases.
  • The DCU:
    • Deathstroke has this as one of his powers. Eventually retconned in favor of the explanation that he uses his brain in various ways that regular humans do not; his grey matter got re-routed and reprogrammed (which makes slightly more sense, at least in terms of comic book science).
    • JLA (1997) reveals that millennia ago, when man was still primitive, a group of White Martians came to Earth and deliberately tampered with their genetic code, reducing their brains and bodies to ten percent of their potential. Had the Martians not done this, it's implied that humans would be greater than the Kryptonians.
    • The Key from Justice League of America once claims to have tapped into "the ninety percent of the brain we never use" via a device he built, which allows him to devise all manner of amazing plans and schemes. This is an aversion, though, as it also drove him completely mad, leading to the implication that he only thinks he's tapping into new parts of his brain. This is later lampshaded and mocked by the Key himself in Batman/Superman: World's Finest when he tells the captive David Sikela/Boy Thunder/the future Magog that this trope is a load of BS and that he used those chemicals and devices to make him smarter.
    • Superman:
      • One Silver Age story involves a computer which is supposed to be designed like a human brain (but is the size of a small room). Its creator explicitly laments there being no power source "powerful enough to activate all its circuits at the same time" and wonders what it might be capable of if there were. Then he decides to program it with a human personality... by hooking it up to Clark Kent's brain.
      • One odd story features a stand-up comedian having part of his unused brain areas activated in an accident, which gives him telekinetic powers, which he uses unconsciously to become a sand-covered monster and try to amuse people to counter his fear of not being laughed at. He's only cured once Superman uses his super-laughter so that he can finally hear through all the sand that someone is laughing.
  • This fake statistic appears in the Iron Man mini Hypervelocity, as the AI protagonist is frustrated at being forced to function at a relatively slow "cognitive clockspeed".
  • In a statement that impressively manages to be wrong in every particular, Marville gives us this as an add-on to reciting the 10% myth verbatim:
    Guy Who Is Probably God: Listen, it would be a disaster if humans used all of their brainsnote Einstein got 20% morenote  and he accidentally drew the roadmap that led to nuclear weaponry.note 
  • Peter Cannon, Thunderbolt is sometimes said to use 100% of his brain, thanks to quasi-mystical training. Recent treatments of the character have at least implicitly acknowledged the mythical nature of the claim; Cannon simply perceives things nine times as well as most people.
  • According to Todd Ingram in Scott Pilgrim, ninety percent of your brain is filled up with curds and whey. Hence his telekinetic vegan power. Arguably an aversion, though, as Todd is shown to be the dimmest and least imaginative of the League of Evil Exes. While it is canon that veganism gives psychic powers in the Pilgrim universe, Todd's explanation comes off more like a thinly veiled insult, and Kim in particular seems skeptical. Also, when he's revealed to have broken the rules of veganism, rather than losing his powers naturally, they're removed manually by the "vegan police".
  • Valiant Comics invokes this with the Harbingers, people with superpowers. Unlike their equivalents in some other comic universes, Harbingers are not physically different from other humans. Elevated levels of activity in their brains result in psionic abilities that give them their powers. Ordinary humans can duplicate Harbinger powers through the use special cybernetic brain implants.

    Fan Works 
  • This turns out to be how the Diadem of Ravenclaw works in The Arithmancer. It allows the conscious mind full access to all the sensory information, processing power, and memories that the subconscious normally filters out. Normal people can't handle that level of input and overload, but Hermione has been training her entire life in the sort of mental discipline necessary to handle the Diadem.

    Films — Animated 
  • In the film of AKIRA, it's stated that everyone has powers, but they aren't always "activated". The Espers have medication that keep them under control to an extent, though poor Tetsuo doesn't, ultimately leading to his ultimate form.
  • Gundam:
    • Mentioned in Mobile Suit Gundam: Char's Counterattack, maybe as an explanation for why Newtypes exist — that people used only a part of their brains on Earth, and began to use the rest after moving into space. However, it's said to be "half" of the brain being used, not 10%. Also, the conversation is between a couple of teenagers, so they may simply not know what they're talking about (they also take a fairly romantic interpretation of the idea/purpose of Newtypes, which Gundam goes back and forth on).note 
    • The fifty percent figure is brought up again in Mobile Suit Gundam Narrative, though it is again said by a teenager who isn't shown to have any real education in the subject.
  • The aliens in Stan Lee's Mighty 7: Beginnings have superpowers because they use 80% of their brains as opposed to humans using 10.

    Films — Live-Action 
  • In Defending Your Life, everyone on Earth is said to use 3-5% of their brains. When a person dies and goes through the Celestial Bureaucracy, they have the chance to move up to the next level, where it's possible to use more of their brain. Then after that lifetime, they have the chance to move up to the next level and so on; each level allows one to use more and more of one's brain, which means being more intelligent and less afraid.
  • This is part of the plot of Flight of the Navigator, in which a young boy discovers an alien probe had experimented with using the unused ninety percent of his brain for data storage.
    Max: Back on Phaelon, we discovered that your inferior species uses only ten percent of your brain. So we filled it all the way up with star charts to see what would happen.
    David: What happened?
    Max: It leaked.
  • Inception says that this is why in dreams your brain can work faster, as the majority of your brain's processing ability is devoted to processing sensory perceptions. With the use of shared dreaming technology, the brain can work much faster, allowing for a dreamworld hour to pass in minutes in the real world.
  • This is pretty much how Extremis is applied in Iron Man 3. Aldrach, through years of research, has found that the human brain has an empty space, hinting that humanity is not at the apex of evolution.
  • Spoofed in Italiano Medio. A clever but insufferable man is convinced by his friend to take a pill that reduces his brain capacity to 2%, to make him complain less and enjoy life more.
  • In The Last Mimzy, the characters' newly-unlocked abilities include telepathy, telekinesis, and super-hearing, as well the ability to control spiders by emitting certain frequencies, to send objects through small warp portals, and to draw ancient patterns without ever having seen or heard of them. In the future, levitation is also a standard part of humanity's milieu.note 
  • The Lazarus Effect calls out this trope's misuse... and then goes right to saying that newly resurrected Zoe is using all of her brain, all of the time, as an explanation of her Psychic Powers.
  • In Limitless, Eddie takes a novel drug, NZT-48, which the dealer claims to allow him to access 100% of his brain as opposed to "the twenty percent". Of course, since the dealer is clearly lying about everything else he says about the drug, such as it being "FDA-approved", he was probably just making up whatever he felt would get Eddie to take it. The actual effects of the drug are flawless information recall, maximized reflexes and extreme situational awareness, which simulate super-intelligence, precognition, and a host of other low-grade superpowers.
  • In Lucy, unlocking more and more takes the eponymous protagonist down the Jean Grey path of increasing mind powers. Using 100% of one's brain capacity leads to omniscience and omnipotence, making the title character practically a Physical God. The trailer also features a character said to be one of the world's top experts on the workings of the human brain repeating the misconception. According to Word of God, they were aware this is just a myth but chose to go with it anyway as a What If?.
  • In My Favorite Martian, Uncle Martin states that Martians have gained their powers due to fully using their brains, unlike humans who use less than ten percent. Tim protests that humans use more than ten, only to get the reply "Your astronauts pee in their spacesuits. Case closed."
  • In My Stepmother Is an Alien, the alien Celeste explains that "We use 104% of our brain capacity, as opposed to your 36%."
  • It is implied in Phenomenon that the incredible mental and psychic abilities George suddenly gains after seeing a strange light in the sky is caused by a tumor spreading across his brain and activating unused parts of it (but also killing him).
  • Besides his milk-white complexion and hairlessness, this is what made the protagonist of Powder so special.
  • In Race to Witch Mountain, the extraterrestrial humans Sarah and Seth have access to telekinesis, telepathy, and phasing, which Sarah states the humans on Earth cannot use yet, because they "haven't learned to use that part of [their] brain yet." Ironically, in an interview with AnnaSophia Robb, who plays Sarah, she confirmed that the director wrote that line in because he wanted to be "as scientifically accurate as possible."
  • In Scott Pilgrim vs. The World, vegan evil ex-boyfriend Todd Ingram claims the source of his psychic powers is that he's able to use more than 10% of his brain because it isn't gunked up with all that filthy animal protein. However, it's more likely that he's an Unreliable Narrator, given that 1. the Vegan Police are able to take those powers away, suggesting that they were granted to him and not an inherent ability, 2. he still seems to be able to use his powers after breaking the 3-strike rule, and 3. Todd is actually pretty stupid.
  • Implied at the end of The Shadow when the Big Bad gets a glass shard through his head and has to have a part of his brain that "no one uses" removed. It turns out that this was where his psychic powers were located.
  • The Sorcerer's Apprentice uses this trope to explain how sorcerers get their powers.
  • Tommy Boy: Richard uses this as an insulting mnemonic device to help Tommy remember the figure 1.5%.
    Richard: Let's say the average person uses 10% of their brain. How much do you use? 1.5%. The rest is clogged with malted hops and bong resin.
  • Referenced for the sake of a joke in Wedding Crashers. "You know how they say we only use ten percent of our brains? I think most people only use ten percent of their hearts."

  • There are plenty of jokes referring to people without any brain at all working as politicians, lawyers, and the like.
    • An old joke tells of a Brit, a Frenchman, and a German arguing whose medicine is better; the Brit mentions a man whose kidney was removed and he went back to work in three weeks, the Frenchman mentions a man whose lung was removed and he went back to work in two, and the German mentions a man whose brain was removed and he went on to lead the country within a week. Modern variants often replace the three with men from different states, the last one being a Texan talking about George W. Bush.
    • A famous line from The Wizard of Oz also riffs on this:
      Dorothy: How can you talk if you haven't got a brain?
      Scarecrow: I don't know. But some people without brains do an awful lot of talking, don't they?
    • An old joke goes: An Englishman decides that he wants to become a naturalized Irishman, but he's told that in order to do so, he must have 10% of his brain cut out, leaving 90%. He goes ahead with the operation but when he wakes up, a doctor tells him, "I'm terribly sorry but we made a mistake. Instead of cutting out 10% of your brain, leaving 90%, we accidentally cut out 90% of your brain, leaving 10%." The man thinks about this for a minute, then replies, "She'll be right, mate!"note 


  • The Radio 4 show More or Less debunked the myth in 2014, with the aid of cognitive scientist Professor Sophie Scott. In 2023, the spin-off More or Less: Beyond the Stats addressed the follow-up question "So how much of our brain do we use?" Another neuroscientist, Professor Daniel Graham, claimed tests using electrodes on the brains of animals suggest that at least 50% of the brain was "dark neurons" that we'd evolved beyond needing, while Professor Scott remained firm that MRI scans show activity in 100% of the brain. (And even Profesor Graham was clear that accessing the "dark" 50% wouldn't give us superintelligence, but more likely the ability to gnaw on bark or make our skin twitch to shoo away insects.)

    Tabletop Games 
  • Aberrant uses this as part of the Meta Origin for novas. Most humans have an underdeveloped, uncharted node in their brain that maps the background forces of the universe. When a nova Erupts, this node becomes active, allowing for limited manipulation of reality — a.k.a., superpowers.

    Video Games 
  • Assassin's Creed makes use of this trope to explain where the accumulated memories of ancestors that all humans have in its universe are being stored. It also uses it to explain Eagle Sense and Eagle Vision, extranormal senses that only some people with a greater than usual concentration of DNA from the Abusive Precursors can learn to use.
  • In Disgaea 4: A Promise Unforgotten, this is given as the reason why Fuka, a human Ordinary Middle School Student, can keep up with her demon teammates. She deluded herself into thinking the afterlife is All Just a Dream, and since it's her dream, she's free to do anything she wants. This allows her brain to unlock her full potential.
  • In Dragon Ball Online, set more than 200 years after the main series, this happened with the book "Groundbreaking Science" written by Gohan, explaining Ki manipulation to the saiyan blooded humans.
  • In Resident Evil: Outbreak, beating the first scenario with Yoko Suzuki has her cite the trope while waxing poetic about the outbreak around her. She really should know better, having been formerly employed as an Umbrella researcher.

    Visual Novels 
  • In Chaos;Head, Norose muses that Gigalomaniacs use the remaining 90% of their brain unlike normal humans, and this is responsible for their abilities. Possibly even worse, it's also stated that 80% of the brain is used for processing visual data.

  • Sofia of Breakpoint City explains her telekinesis this way.
    "You know how most people only use 10% of their brain? I use 11%."
  • Casey and Andy examines this, thanks to Anti-Stupid Science Man!
  • El Goonish Shive:
    • In one strip of EGS NP, Susan complains about Lucy, saying it's "based on a 'fun fact' that isn't even true! You might as well make a movie about an assassin who uses daddy-long-legs venom!"
    • Later, in the main strip, an Immortal starts telling a series of Blatant Lies in order to demonstrate to a confused griffon that Immortals are capable of lying. This is one of them.
  • FreakAngels seems to be hinting at the fact that they have simply not reached their full psionic potential. Arkady's continual experimentation with her abilities seems to be a testament to this.
  • When one member of Belinda's medical staff mentions this myth in this strip of Legostar Galactica, she answers by delivering an angry rant. (The comic's author once was a neuroscientist himself, so this is quite understandably a pet peeve of him.)
  • Mentioned in Paranatural, during a battle with their teacher possessed by Hijack (a spirit shaped like a brain). When Max complains that Hijack has too many abilities, he used this mixed with Insane Troll Logic.
    Hijack: Well, the brain is like a muscle, and you only use 10% of your brain. But I'm 100% brain, so—
  • Penny Arcade:
    • A joke that unfortunately never made it into the comic but does show up on their podcast uses the concept:
      "You know how people only use ten percent of their brain?"
      "I've heard that."
      "Well I only use ten percent of my penis."
    • One strip uses this trope as part of an advertisement for "air for gamers".
  • Parodied in Scary Go Round when a man survives having 90% of his brain eaten by a zombie because by incredible coincidence — she ate only the 90% that no one uses.

  • This AV Club spoof of Lucy suggests that Hollywood should make other movies based on inane common beliefs.
  • A Cracked article compares this notion to becoming a better writer by using every key on your keyboard in every sentence.
  • The Onion parodied the concept with a man who invented a device that lets him fire all his neurons at the same time. Every time he turns it on, he has a seizure.
  • SCP Foundation:
    • SCP-1475 is a deliberate Deconstruction (the author even flat-out stated that his inspiration for writing it was his hatred of this trope). He gave himself a non-reproducible drug that lets him use 100% of his brain 100% of the time. This not only gave him complete control over his body but let him rewire his brain so that he doesn't need to sleep anymore. However, in a true case of Blessed with Suck, this completely destroyed his autonomic nervous control (that is, the body's ability to automatically regulate the heart/lungs/etc.), so he has to spend most of his concentration on keeping himself alive. Not only does this not leave him much concentration to use his voluntary muscles, but he's also suffered permanent damage to a lot of his organs due to having messed it up in the past.
    • Surprisingly played straight with SCP-3733, which is described as activating "several typically inactive areas of the brain, resulting in the ability to act and reason outside of one's experiences and personality". That's because the entry is from a world where an unknown entity has hijacked humanity's collective mind and suppressed their emotions and individuality. The SCP is the aforementioned concepts, which is now being contained by the Foundation.
  • Villain Source sells brain pills that are guaranteed to increase your IQ by 300% or your money back! (The small prints adds that if you believe this, then you really need those pills.)

    Web Videos 
  • CGP Grey discusses this trope, with a bit of a Take That! at the end:
    "If you really think someone could scoop out 90% of your brain, and you'd be alright, then perhaps you really do only use ten percent of it."
  • In To Boldly Flee, it's stated that a critic's brain usage is typically 5%, but Ma-Ti's brain uploading has boosted Spoony's brain usage to 92%.

    Western Animation 

    Real Life 
  • Truth in Television to an extent; humans can still function (though not to full capacity, obviously) if parts of their brains are removed. Most notably, the practice of lobotomizing criminals was considered a humane alternative to the death penalty for quite some time. Splitting the corpus callosum (the tissue connecting the two hemispheres of the brain) was a common cure for seizures in the 70s (and is still occasionally done in severe enough cases).note The side-effects only occur in very specific, usually engineered scenarios, and are much preferable to the seizures in the first place.
    • Removing a damaged hemisphere can even result in a significant improvement in cognitive function... in the other hemisphere, which rewires itself and takes on the tasks once done by the removed half. Whether it improves overall ability is unlikely, given that split-brain patients often act like two people sharing one body, and often work at cross-purposes.
    • The basic rule now is that you do not remove any part of the brain unless it's absolutely necessary, because functions are centralized to specific parts, and depending on what is being lost and the patient's age there are distinct upper limits to how much function will be regained. People have permanently lost the concept of color, while prefrontal lobotomies are a good source of Nightmare Fuel...
  • One source of the myth itself (of many possible ones) is a series of experiments done on rodents in which the poor creatures had large parts of their brains burned away but could still run a particular maze. However, all this proves is that memory is distributed in the brain rather than localized; the rodents still lost other functions. Besides, mice aren't men.
  • Approximately 90% of cells in the brain are not actually neurons, but glial helper cells that keep the neurons alive and functioning. So only 10% of the cells are used directly; the other 90% are vital to keeping that 10% healthy and alive.
    • However, not only are these cells necessary for brain function, but if you stick human glial helper cells in mouse brains the mice become smarter, suggesting that they do play a pretty important role in cognition.
  • The famous Phineas Gage had a tamping rod driven clean through his head after he struck it with a sledgehammer when too much gunpowder had been poured into its hole, causing massive damage to his frontal lobes. He recovered, memories and abilities mostly intact, but with a radically changed personality-friends and family said he was "no longer Gage." Despite the injury, he managed to live for another twelve years. He was long used as an example of the effects of damage to the frontal lobes on a person, but the severity of his personality changes are now questioned due to a lack of actual records of what he was like from before the accident.
  • There is a famous case of a character who came to a doctor complaining of headaches, and turned out on the X-rays to have no cerebellum. Apparently, he'd been born without one, and the cerebrum had simply taken over all the necessary tasks—to such success that he was working as a steeplejack!
  • Dolphins and other cetaceans have adapted to function actively while 50% of their cerebrum is asleep. This is good, since their breathing is entirely under conscious control, and total loss of consciousness thus equals suffocation.
  • Some birds can also have half their brain asleep while the other half keeps watch for danger from one eye.
    • Generally speaking, all air-breathing aquatic animals and all land-based prey species that sleep out in the open do this as well, sleeping with only half their brain at a time. Only animals that tend to hide themselves in very well protected locations such as dens or single-family bungalows in the suburbs can afford to sleep with their entire brain.
  • Autistic savants are people who, due to cognitive disabilities, have focused on specific skills and as such have refined them to an unusually high skill level, sometimes operating in a somewhat bizarre manner (such as some artists who, rather than sketching, immediately start drawing the finished drawing piece by piece in proportion; some of these skills can be extremely narrow or bizarre as well). While the common perception is that this is a Disability Superpower, in reality ALL humans are capable of developing savant-like abilities, and indeed many "ordinary" people do have savant-like abilities. The reason savants stick out so much is because their ability is so far in excess of everything else that they can do, they become defined by it as far as other people (and frequently they themselves) are concerned. People who don't suffer from cognitive disabilities aren't referred to as savants, they're just viewed as highly skilled individuals.
  • There was a girl who had half her brain gone. The left hemisphere was just not there. So far she seems to be living a fairly normal life with a fairly normal, if quirky, degree of intellect.
    • While half of the brain can be removed in a young child and they can still live a fairly normal life due to the other half compensating (due to the symmetrical design and the child's brain being extremely flexible) it's worth adding that an adult who had half their brain removed in adulthood would not be able to function properly.
  • A man from Florida lost a good portion of his brain in a car accident and was left with a flattened cranium. Memetic Mutation struck when his mugshot was posted to the Miami New Times website.

Alternative Title(s): Ten Percent Of Your Brain