In Detective Conan, an Asshole Victim ruined the career of a promising young pitcher by (falsely) claiming that there was something wrong with his pitch, after which the poor kid destroyed his own shoulder trying to figure out what was wrong.
Another victim died when her murderer induced semantic satiation on the word containing her last name, and then asked her to sign an important contract. (The poison was carefully applied to the edges of the dictionary that the victim would touch upon looking up the word.)
In one The Adventures of Tintin story, The Red Sea Sharks, Captain Haddock is unable to sleep after Allan mockingly asks him if he sleeps with his beard under or above the covers. This ends up saving his life and those of everyone on the ship. (Captain Haddock is shown to sleep on his stomach in Tintin and the Picaros.)
In Cerebus the Aardvark, the title aardvark tries to win a ball game using this trope, asking if he breathes in or out when tossing the ball. Cut to panel of his panicked partner contemplating it. Cut to panel showing said partner having won and saying, "I breathe out!"
In one Archie Comics story, Jughead beats Reggie at bowling this way.
Linus: I'm aware of my tongue ... It's an awful feeling! Every now and then I become aware that I have a tongue inside my mouth, and then it starts to feel lumped up... I can't help it... I can't put it out of my mind.... I keep thinking about where my tongue would be if I weren't thinking about it, and then I can feel it sort of pressing against my teeth..."
Similarly, in a storyline Linus is asked how he tied his shoes, and he has to go barefoot for the rest of the week.
PHB: The problem with engineers is that they don't idle well.
Parodied with another series where Dilbert loses the connection between effort and reward and realizes that he still gets paid if he stands around flicking his fingers. Eventually the entire office is doing it, and the boss thinks to himself "I don't know what success sounds like, but I don't think this is it."
Also happens to Ratbert once when Dogbert muses on how we unconsciously manage incredibly complex nervous signals to move our muscles; stopping to think about it, he immediately goes into a spasming fit as a Funny Background Event.
Beetle Bailey: What do you do with your arms when you're walking? Mort Walker was nice enough to show a character walking before thinking about this and swinging them in the opposite order from how he moved his legs so that the reader didn't have to face the puzzle.
In Chapter 8 of the fanfic It Takes a Village Spike finally figures out how to fly. He immediately makes it clear that no-one is to ask him how he managed it, otherwise he might forget.
In the second chapter of A Delicate Balance, after Twilight Sparkle realizes that she has a crush on Applejack, she makes a determined effort to act as normal as possible around her, and fails precisely because she's thinking too hard about what she should be doing. Another scene has a distracted Twilight pick up a cup with her hooves rather than with her telekinesis. She manages just fine until she realizes that she's holding it that way, at which point she promptly spills it.
Films — Animation
In Kung Fu Panda, Po is utterly incapable of performing any kind of kung fu. He can, however, punch through doors and do perfect splits while trying to get food. Fitting the original usage of the trope, the moment it's pointed out to him he's ten feet off the ground he falls flat on his face.
Films — Live-Action
In The King's Speech, Lionel Logue points out that this is Bertie's problem (though it's a significant problem and not easily surmounted) by having him recorded reading Hamlet while listening to music that make it impossible for him to hear himself. It's not until much later, after getting drunk and dismissing Logue as a crackpot, that Bertie listens to the recording... and hears himself speaking without a stutter for the first time in his life.
In Bull Durham, the hot young pitcher has no control when he thinks about what he's doing, and his catcher exploits this, goading him into throwing a fastball right at his chest from five feet away, and he misses. His girlfriend makes him wear garters under his uniform, and he's so twisted around thinking about how uncomfortable he is that he pitches beautifully.
One joke that comes up sometimes on the internet is to simply write "You are now breathing manually." (or blinking, reading, listening — anything the reader is expected to be doing at the moment), which actually makes some people stop to reorganize their thoughts.
Another joke is about a college student asking his bearded professor if he sleeps with his beard above or below the covers. The professor shrugs and says he has never thought about it. The next day, the professor comes to class with bloodshot, baggy eyes and grabs the student: "What the hell did you do to me? Now I can't sleep. It's uncomfortable either way."
In The Hitchhiker's Guide to the Galaxy it is possible to fly as long as you don't think about the fact that you're flying. It's not terribly hard. All you have to do is throw yourself at the ground and miss (the only way to miss is to distract yourself somehow right before you hit the ground).
One of the Callahans Crosstime Saloon stories by Spider Robinson is actually titled "The Centipede's Dilemma". In it, a character with a dangerous psychic ability is defeated and rendered powerless by using this technique.
Discworld: Referenced in A Hat Full of Sky. Miss Level once had this trope described to her by an acrobat: "Never ask the tightrope walker how he keeps his balance. If he stops to think about it, he falls off." This principle helped her out later on. This was proven on a Derren Brown show, where he asked an experienced tightrope walker stuff like that, and repeatedly told him not to fall off. Guess what happened next.
In Walter Brooks's Freddy the Pig series, at one point a beetle came to Freddy saying he couldn't walk anymore, since every time he tried he got distracted by where his legs were and tripped. Freddy had him stare at the ceiling while he walked, and it worked.
There is a French story called "La Barbe", where everyone asks a man with a long beard how he sleeps with his beard. In an attempt to answer the question, that night he tries many different sleeping positions, and is unable to get to sleep. The next day, he gets his beard shaved off.
The First Men in the Moon begins with Bradford's attempts to write a novel being confounded by Cavor — who keeps walking past his house, shaking his shoulders and making strange noises to himself. Bradford confronts Cavor over it, and Cavor confesses that he's a scientist and that he finds his daily walk to be the best time for thinking about his research — and he's so engrossed in his thoughts that he had never noticed that he was acting so outwardly strange. About a week later, Cavor confronts Bradford—he hasn't been able to make any progress on his research in the past week, because every time he goes out for a walk he's too focused on the walking to get any thinking done. When Bradford offers to help with his research, Cavor brightens up, and as he walks back to his house, he begins shaking and making noises in his old manner.
In The Baby-Sitters Club book "Mallory Hates Boys (and Gym)", when Mal's name is called to be on one of the volleyball teams and she starts jogging over to her teammates she suddenly becomes very conscious of her arms.
Stephen Potter's satirical how-to-win-at-games-without-being-able-to-play-them book Gamesmanship lists breaking your opponent's flow in this manner as a fundamental technique, explicitly stating "CONSCIOUS FLOW IS BROKEN FLOW" as being "Rule 1".
In the Dresden Files book Ghost Story, a newly-formed ghost (Harry) is in a car when a comment from Mortimer Lindquist makes him realize there is a logical flaw in the fact that he can walk through walls, but is sitting here in a car. Before he can even complete the thought, he's fallen through the bottom of the car. A more experienced ghost drags him back up and explains this trope.
Jamie Lannister encounters this due to a case of Damn You, Muscle Memory in A Song of Ice and Fire after the loss of his right hand forces Jamie to have to learn to fight using his left and finds himself having to think about his every action.
Hilaire Belloc's poem The Water Beetle describes the same effect on the pond skating creature, who would immediately sink if he stopped to think how he does it.
In Harry Potter and the Chamber of Secrets we learn that, when interacting with snakes, Harry has been speaking to them via Parseltongue without realizing it. Later, when he needs to use it without a real snake around to trigger it, he has a much harder time doing so.
Later, in Harry Potter and the Half-Blood Prince, Dumbledore takes Harry to view a memory involving a family called the Gaunts. Harry fails to realize the Gaunts speak in Parseltongue until it's pointed out to him.
The Heroes of Olympus: In book one, Leo Valdez, as a son of Hephaestus, has the ability to operate any piece of machinery. When he needs to fly a helicopter, he is explicitly described as going back-and-forth between doing things right without thinking about them and doing things wrong by thinking about them.
In Little Mosque on the Prairie, Sarah spends all day accidentally insulting people after Fatima asks her how she always knows the right thing to say.
Kenneth tries to ask Liz a question, but she is in a hurry so he responds "Can you walk and talk at the same time?" Kenneth: "Well, normally I can, but now you've got me thinking about it" and he immediately starts staggering and slurring his words for a few paces.
Jack in "Jack-Tor", who forgets how to walk, hold his arms, or enunciate words when the camera is on him.
Raj on the The Big Bang Theory needs alcohol before he can talk to women. In one episode he has a beer and starts hitting on Summer Glau, until Howard points out the beer was non-alcoholic, and Raj can't continue.
In The Young Ones, after some incredibly mean-spirited negative vibe-merchant boards Neil's bedroom up, meaning he can't get to his wardrobe, Neil is forced to protect his modesty using a plant pot. The plant pot incredibly manages to stay on without any visible means of support...until Rik asks him how he's keeping the plant pot on?
In Community, when Jeff becomes a law teacher, he spends a lot of time confused about what he's supposed to do and is unable to actually teach, falling back on lazy excuse assignments to give his students. After his students watch him successfully Logic Bomb Annie with her own though process, they ask him how he managed to pull that off and he winds up accidentally teaching a lecture on how to win an argument in that manner.
The Scottish folksong of "The Wee Kirkcudbright Centipede" who is an incredible dancer until someone asks her to demonstrate her dance step-by-step. She basically ties her legs together.
This is the whole point of, oh, all of ancient Greek esotericism, and therefore of half their myths. Hesychastic union with the divine, or the noetic experience of the Monad, ceases once you begin having discursive ("dianetic"note No, he didn't make that word up.) thought about it. Hence the Orpheus myth: the moment he looks to see if Eurydice is there, she vanishes back to the realm of the dead.
The term comes from an 1800s poem by Catherine Craster, but the Zhuangzi (3rd century BCE) features a near-identical story. Here, a being with one foot asks a millipede how it can walk with all those legs. The millipede responds that it doesn't think about it, simply 'setting my heavenly impulse into action'. This is consistent with the "do what comes naturally, don't expend unnecessary effort" philosophy of Daoism.
A lot of games, especially songs with weird rhythms in Rhythm Games can be easy for an experienced player until they actually try to break down exactly what they are doing. Similar to how a player doing extremely well starts faltering once they realized it.
Jade Empire: Wonderfully referenced when you ask Kang how he manages to remotely pilot the Marvelous Dragonfly from the ground.
"Well, it's much like the dilemma of the centipede. If he relaxes and lets things happen, he can walk naturally all day long, his hundred legs not missing a step. But, if he thinks too hard about the complexity of what he's doing, those legs might crash into the teahouse and kill everyone. A valuable lesson."
Invoked in-universe in Divine Divinity. The Player Character encounters a pair of skeletal mooks discussing the inherent Fridge Logic of their design, like how they really shouldn't be able to speak, walk, or even stay assembled without any muscle mass, skin, tendons, or internal organs. It eventually causes them to fall to pieces.
Near the end of Metal Gear Solid 2, the game starts deconstructing itself as a mechanism for simulated emotional responses and player catharsis. An AI construct, in a lengthy radio conversation, spends ten minutes dissecting the postmodern condition, the player character's personality, and his role as a vehicle for the player. The player is left to wonder what the point of fighting is if he's just being manipulated by the game and its fictional stakes.
Parodied in Poker Night 2 when Sam asks Claptrap how he balances on one wheel. Claptrap starts wobbling and panicking...and then laughs, explaining he's got "More gyroscopes than the Hubble."
Lampshaded at least once in Tiny Toon Adventures — they can walk on air across a canyon as long as they don't look down.
Also played with in an episode where Bugs Bunny and Elmer Fudd meet as small children. Elmer runs off a cliff, and Bugs tries to make him fall by pointing out that gravity should pull him down. It doesn't work, because Elmer is just a little kid and hasn't learned what gravity is yet. Bugs is later kind enough to provide him with a definition.
Happens to SpongeBob when he tries to explain how shoelaces are tied, and gets so mixed up that he entirely forgets how to do it. Fortunately, Gary provides a "how to tie your laces" recording to teach him the process all over again. Actually, he realizes his shoes have always been tied.
Another episode has SpongeBob forgetting how to "assemble" a Krabby Patty after a rival falsely tells him he forgot the pickles. It comes to a point where he tells Mr. Krabs that he cannot do it while saying the steps, then realizing he did just that.
When Skull Boy loses his lucky charm on the eve of a quiz game championship in Ruby Gloom, he finds it impossible to answer even the simplest questions. What falls into this trope is that throughout the second half of the episode Ruby offhandedly asks him questions several times that he answers without thinking, only to fall apart when this is pointed out to him.
A credits gag in an episode of Fish Hooks has Snake reading a book on animals and comes to the point where it says animals don't talk. When she points it out to Mouse they suddenly lose this ability.
In military, the Close Order Drill, "square bashing", originates in overcoming this issue. Making the movements automatical and instinct in the muscle memory creates the basis on action on battlefield.
Learning "Drill and Ceremony" (D&C) in the military is an example. Teaching a soldier how to march makes him or her consciously think about how their arms and legs move during what is, essentially, "precision walking". It literally takes weeks to learn how to march to the proper cadence. Not to mention a plenitude of other skills in the military, such as firing a weapon, or disassembling and reassembling equipment for maintenance or repair. Particularly important if you need to fire, disassemble, and reassemble your weapon in the midst of combat (such as when needing to clear a misfire from your weapon). Also note that you may need to do this, and any other important tasks, while also dealing with the mother of all fight-or-flight induced adrenaline surges.
In the Finnish Army, the conscripts are taught first to disassemble and reassemble the service weapon at plain sight, then behind one's back but eyes open, then eyes tied, and finally behind one's back and eyes tied (tying one's eyes does affect on muscle coordination and balance). The nimblest can perform it under 30 seconds with the RK 62 assault rifle.
As a general rule, any situation where a person's pulse needs to be taken is also a situation where breathing rate needs to be taken. Since breathing rate is under direct conscious control, the proper procedure is to count breaths and take the pulse simultaneously, and never mention breathing to avoid this trope. And now you know. Hey, we warned you. Somewhat related is white coat hypertension, wherein some people's blood pressures elevate reflexively when intimidated by the idea of medical examinations.
Riding a bike is probably the most famous example: practically everyone learns to ride a bicycle by having their instructor secretly let go of the handlebars so they'll continue riding along without thinking about it. If you try to worry about how the bike's staying upright, you're bound to lose your balance. Likewise, steering a two-wheeled vehicle requires briefly countersteering (turning away from the intended direction) to get the bike to track into the turn. This is done automatically by new riders, but when trying to master leaning they often skip this step, keeping the bike from turning much no matter how much they lean.
Just about any time you realize you're performing a complex series of actions (e.g. a sequence of keystrokes) over and over again, you're likely to start thinking about how you're managing to do it so fast — and immediately screw it up or have to slow down. Some people have reported typing quickly when they felt they were typing slowly, and upon realizing that they typed quickly, they either couldn't type quickly anymore or couldn't type both quickly and precisely anymore.
Anyone who's learned to drive stick shift after first learning to drive on an automatic knows this trope intimately. All the complicated motions and checking of gauges and looking around that have become instinct fall apart with the addition of just one more thing to do. Nothing you internalized involved moving your left foot or paying attention to the RPMs, and that's enough. And people who drive stick and shift to automatics have to remember that they don't have to use their left foot. Also, the reason drivers from Britain to America, and similarly flipped countries, have trouble has less to do with switching sides and more relearning driving. Roundabouts for instance, making turns, even something like checking mirrors for traffic. Try parallel parking with a different side.
It also works in reverse, when you start thinking about what to do with your (now unused) left foot, although it's more a case of Damn You, Muscle Memory.
Pianist Glenn Gould said this about his piano playing.
A mild version can be experienced by saying, reading, or thinking about a particular word too much (try all the uses of the word "pink" on the Pink Product Ploy page for a good example.) After a certain number of repetitions the word itself will lose all meaning to you. Your brain still consciously knows it's a symbol for something, and know what that something is, but it feels like you're no longer using a word, but rather a really weird symbol that means the same thing. It is called semantic satiation.
There is a ploy in American football called "freezing the kicker" or "icing the kicker" which relies on this trope. When one team is lining up to kick a field goal, normally accomplished within a set period of time while a play-clock is ticking down, the opposing coach calls a meaningless time-out just before the play is about to start, to stop the clock and give the placekicker a minute or two to overthink his kick. In some studies this has been statistically shown to work on certain attempts, as kickers have a slightly lower success rate after being "frozen".
This is a major factor in professional athletes "choking" generally, and in fact can cause them to do so more often than amateurs.
On that note, Shaquille O'Neal's infamously poor free throw shooting. Throughout his career, Shaq was a decent-to-good free throw shooter in practice; in a game situation, with nothing going on around him and everybody in the stadium looking right at him, however, he couldn't deliver.
This is also why, in Major League Baseball, if the pitcher is throwing a no-hitter, it is considered 'EXTREMELY dickish to point it out to him in the middle of the game. Now he's going to be thinking about it, and will probably choke.
This ESPN the Magazine article discusses this in analyzing pro golfers who sought to improve their game by changing their swing. In almost every instance, a promising, skilled golfer lost every bit of promise and skill the second he took a look at his swing.
Sometimes people have this dilemma with sleeping. It happens when you're lying in bed, tired, but then you start thinking about sleep. Thus you become too conscious to relax. It'll happen sometimes when you need to be up earlier than usual the next day and try to force yourself into sleep. If you're told that you don't actually need to sleep, often you then fall asleep easily, as the stress and therefore the need to focus on the process is resolved.
In German primary schools, the kids sometimes have to take grammar tests that involve conjugating verbs in their own language. Usually, they're able to get the verb forms right in their sleep, but when they're explicitly asked to compose, let's say, the second-person singular form after being taught how it's assembled from a verb stem and a suffix, some suddenly get it wrong even though it's their own mother tongue. Might occur in other languages as well.
For the same reason, foreign language classes now teach much less grammar than they used to — knowing the grammar too well often left people stuck and unable to speak.
The concept of "immersion" in fiction. Writers of escapist stories try their hardest not to draw their readers' attention to the fact they are reading a book, watching a movie, or playing a video game. Once viewers remember that they're watching fiction (usually due to bad writing like Said Bookisms, or something not making sense) their ability to escape into the story drops drastically. Some postmodernist writers and directors, like Bertolt Brecht and Hideo Kojima, deliberately invoke this trope to point out the downsides of escapism, by deliberately making the audience aware of the unconscious processes involved.
Try and do something simple like putting on a coat or tying your shoelaces while explaining every step carefully to an onlooker. Suddenly getting dressed has never been harder.
This is common for anyone with a prosthetic leg. They have to relearn how to walk and balance themselves as their body is used to doing it one way, and they are trying to mentally go through the steps. One of the most common ways to get around it was to literally distract the patient in his therapy after they had proven able to do all the motions required so that they stop thinking about it. It still usually takes a few weeks.
They also have to deal with the severely reduced tactile feedback from the skin and muscles that used to be there. You don't consciously notice, but your brain receives and processes literally thousands of sensations every second. When a person loses a significant part of their body, like a leg as stated above, those thousands of messages are basically replaced with "FILE NOT FOUND", so the brain has to create workarounds.
Does this door open inwards or outwards?
A condition called spasmodic dysphonia causes the sufferer to be unable to speak in spontaneous conversation, though they can often still speak in routine ways such as singing, rhyme, recalled speech, or vocal reading; acts which circumvent the process of coming up with words. Scott Adams had this.
Take up any martial art or combat sport and after becoming just a bit more skilled than a beginner, think about that perfect spinning backfist, left hook, or lunge. You are quite likely to fail the execution.
People rarely get scared of the dark until they realize they are in the dark. For example, if you wake up in the middle of the night to urinate, then remember that you're afraid of the dark, you'll run straight back to your room.
Something similar can happen to actors on stage. After so much rehearsing, your movements, facial expressions, gestures, and the lines you're speaking turn into muscle memory. The times you forget a line or an entrance are usually when you're thinking too much about what comes next.
Marching band is the same way. Memorizing the 8 minute marching routine which varies step size and direction all the time and 8 minutes worth of music quickly becomes muscle memory and you don't have to think about what you're doing. But fall down, miss a step, or a note and suddenly you don't know what to do until you get out of your own way.
Next time you sign something, think about how you actually do your signature...
When running down stairs, do not suddenly think "Which foot goes next?" You will trip. And likely die.
The sworn mortal enemy of sufferers of obsessive thoughts (PTSD, OCD, etc) is indeed not the obsessions, but the brain that is obsessing in the first place. It's called "ironic processing", and what happens is the victim tries to not think about the obsession. So their brain reminds them not to think about it... by thinking about it. The more they try not to think about it, the more they end up thinking about it by their brain reminding them not to think about it. This trope is why the best thing for obsessive-thought-sufferers to do is distract themselves with something else entirely.
Even though humans don't have nearly as many legs as centipedes, we can suffer from the same problem. Next time you walk, try to think about how you walk, and especially how you look like when you walk. You will still be able to walk, but you'll likely do it more clumsily and awkwardly than before. It is a problem that many people have tried, especially when they were around someone of the opposite sex; they walk perfectly normally, but due to nervousness they think they look stupid, and the result is that they really end up walking in a stupid way.