Ninety Percent Of Your Brain / Live-Action TV

• Referenced in the first episode of 12 Monkeys when scans of Cole's brain reveal that he's using the entirety of his brain. In a twist, the researchers point out that this should be a Grand Mal seizure, except it's somehow organized and controlled, turning him into a human computer calculating something obscenely complex. They don't know what he's calculating, but the audience knows that he's a time traveler who has been modified to survive the journey, implying that this is part of the process.
• Averted in Agents of S.H.I.E.L.D. when Dr. Holden Radcliff explains that it's a myth that we only use 10% of our brains.
• Referenced in episode 5 of Almost Human when an alleged spirit medium says that her powers are the result of the Cerebellux procedure, which enhances use of brain pathways.
• Alphas: Stanton Parrish has a variation of this. He has the ability to consciously control every process in his brain, even those that are not consciously controlled in ordinary humans. This makes him able to instantly recover from any injury and prevents him from aging. However, it comes with several downsides: his emotional relationships with others are disrupted, making him similar to a sociopath, and his ability to retain memories is disrupted to an extent (likely due to the fact that his brain, powerful as it is, still lacks the capacity to hold over 200 years' worth of memories all at once).
• Birds of Prey (2002): Barbara claims that ordinary humans use only five percent of their brains, but metahumans far more. A scan of Dinah reveals that she uses fifty percent.
• Surprisingly played straight in the Black Mirror episode "Black Museum". In the second segment, a man is informed that human beings use only 40% of their brains, so they could upload the consciousness of his comatose girlfriend into the "empty space" of his own brain, allowing her mind to "take the passenger's seat" on his mind. It ends badly.
• Johnny's powers in the television version of The Dead Zone come from the fact that a normally unused part of his brain became active to compensate for a damaged section.
• Eureka's scientific adviser was on record as making sure that when that concept was used on the show, the line was "ten percent... at any one time" specifically to dodge this trope.
• Fringe:
  • The 10% fallacy is averted only to be replaced with a different (even more absurd) rationalization. A Mad Scientist several decades in the past developed a drug that prevents babies from losing the natural potential they have at birth. In a Double Subversion the Mad Scientist in question fails completely in clinical trials only to be proven right when Olivia develops psychic powers. Maybe.
  • Another subversion: the reason why Walter is mentally askew is that 10% of his physical brain was removed and implanted in other people's brains, giving them all bits and pieces of a complex design, in a bit of Lego brain surgery. Getting back that 10% puts him on track to solving an important puzzle.
• Referred to in the premiere of Heroes as an example of one way humanity might make a sudden evolutionary leap, but then mercifully dropped... only to be brought back up in season three, in a speech by Sylar.
• The main plot line for an episode of Honey, I Shrunk the Kids. To make matters sillier, accessing the other 90% gave the character in question godlike powers. All this was caused by a device that was established in a previous episode to be used for brain-swapping.
• Spoofed in an Italian Real Trailer, Fake Movie parody of Limitless, mercilessly titled Italiano Medio (Average Italian).
  Protagonist's friend: You know that story, that we use only twenty percent of our brain? [hands him pill]
  Protagonist: Okay, I'll try it just out of curiosity. [swallows pill]
  Protagonist's friend: With this, you'll only use two percent.
• John Doe actually acknowledges that only about 10% is in use at any given time but implies that tapping into the other 90% at the same time is what allows some of the characters to use their psychic abilities.
• Referred to in Kyle XY. The titular Kyle has a highly advanced brain, learning to speak in one day, and learning kung fu and Chinese from watching an old Bruce Lee movie. They give him a CAT scan and the scan showed he used 80% of his brain. However, the doctors noted this as strange, citing the problems one would have at such levels (such as seizures), and wrote it off as a machine malfunction. It is later shown that if he uses his powers too much, he will get a seizure.
• Discussed and defied in Limitless. Brian attends a party where everyone there is on low-grade NZT. He hears someone saying that you only use ten percent of your brain and that the pill works by allowing you to use more. Brian responds by pointing out that it's a myth.
• In the last episode of Lois & Clark, Dr. Mensa uses the rest of his brain and gets an enlarged brain, the power of mind control and the moniker "Fat Head".
• My Favorite Martian: Cited by "Uncle Martin" as one of the reasons Martians are so much more advanced and intelligent than human beings. Martians use all of their brains, while earthlings only use a small percentage of theirs.
• Disproven in MythBusters — Tory's brain scans show him using 15-30% of his brain, depending on what he's doing.
• Night Man: When Johnny Domino gets struck by lightning and starts hearing other people's thoughts, this is the explanation offered by the medical consultant on psychic phenomena — who's apparently been spearheading our side of an ESP race with the Soviet Union.
• In Seinfeld, when George stopped having sex, his brain was free to do other things, accounting for his sudden burst of knowledge. Jerry compared George's brain to a cabbage, with a tiny leaf being the part he normally devoted to anything that wasn't sex. This seems to work the opposite way for women (as shown with Elaine's sudden stupidity), by which Jerry meant that most of men's brainpower is normally invested toward obtaining sex, while a woman always has men available to take care of her sexual needs for her and never has to think about it herself; therefore a celibate man becomes super-intelligent since his brain is freed up, while a celibate woman becomes super-stupid since she loses all her brainpower into thinking about sex.
• Stargate-verse: The idea that 90% of the brain is unused becomes a major plot point of the Ascension Myth Arc within both Stargate SG-1 and Stargate Atlantis. To be able to Ascend to a Higher Plane of Existence without the aid of an already-Ascended being, the brain must become fully active. As the human brain activates an increasing percentage of the brain, they begin to develop special abilities, such as the ability to heal with a touch, or read minds or move objects with the mind. Usually, such a human will only develop a single ability, but as they get closer to the threshold for Ascension, they begin to display multiple abilities. In SG-1, the Goa'uld are ever in search of powerful hosts to parasitise, so a rare few have experimented with technology to force humans to develop these abilities or even to actually be capable of taking a Goa'uld into Ascension. Atlantis expands on SG-1 when an ancient technological device is found that's supposed to help people artificially reach Ascension by forcibly and gradually awakening the inactive 90%. The catch is that this isn't how the brain is supposed to naturally function and it therefore brings the modified human to the point of permanent seizure. The machine therefore forces the modified human to either Ascend or die.^note The Ancients were a group of humans who'd evolved to have these mental abilities and eventually figured out Ascension. But this was a natural evolution over millions of years, meaning that the Ancients' brains were biologically different from those of modern humans in order to withstand using said powers. The "Ascension machine" forcibly unlocks the abilities in a brain that's not biologically adapted to them, making it the brain equivalent of permanent Uninhibited Muscle Power.
• In Star Trek: Deep Space Nine, this is cited as why Dr. Bashir can lose a portion of his brain and be completely fine (this was before Bashir was retconned to be super-intelligent). It's absolutely not true and is in fact one of the ways we know the 10% thing is a myth; there is almost no part of the brain we can lose without suffering loss of ability.

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