"If I try to think about how it works, it doesn't work."
—Tiffany Aching, I Shall Wear Midnight
A trope named for the folk tale of a centipede who had no trouble walking until asked how he managed all those legs. He started thinking about the process and immediately became unable to do it anymore.
Often encountered during the Bizarre and Improbable Golf Game, when one player attempts to induce a dilemma in his (usually winning) opponent by asking, "Do you breathe in or out on the backswing?" That said, this can show up in any context featuring a complex activity that requires one "get into the flow".
The trope is sufficiently well-known that sometimes the writer will just have someone comment, "Oh, he's got Centipede's Dilemma," or the like, rather than actually explaining what the problem is when Mr. Awesome starts messing up.
Warning: reading the examples below may well cause you to have the same problem that the characters are having.
Compare Achievements in Ignorance, Puff of Logic, Performance Anxiety, Don't Think. Feel, and Magnum Opus Dissonance. Attempting this on a group of people simultaneously may lead into someone biting into the Apple of Discord.
- In one Tintin story, Recap, 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. 
- There's a Garfield strip where Jon asks Garfield which way he puts his feet down when he walked. Garfield is then paralyzed.
- In "The Me Book," Garfield suggests an extremely subtle version for ruining someone's golf swing, in which he instructs the reader to tell the golfer, "Think about your right hip."
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, a storyline in which Linus was asked how he tied his shoes and had to go barefoot for the rest of the week.
- In Cerebus, the title aardvark tries to win a ball game using this trope, asking if he breathes in or out when tossing the ball. Cue to panel of his panicked partner contemplating it. Cut to panel showing said partner having won and saying, "I breathe out!"
- Bored, Dilbert contemplates the connection between his mind and body and forgets how to move.
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 one Archie Comics story, Jughead beats Reggie at bowling this way.
- Harry Potter from Harry Potter and the Methods of Rationality refused to share the secret behind the Patronus V.2, because it is unlikely that the majority of people would be able to reach the mental state necessary, and attempting it could destroy their own ability to cast normal Patronuses.
- In Chapter 8 of the My Little Pony: Friendship Is Magic 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 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.
- 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 (oh, and you have to distract yourself somehow right before you hit the ground).
- One of the Callahan's 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' 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".
- During the MythBusters test to see if you could swim through syrup just as fast as you could through water, the team acquired an Olympic gold medalist swimmer for a more accurate result. They ultimately had to throw his results out due to inconsistency. Why? Because he wasn't used to swimming in syrup, and his focus on what he was swimming through (and how it felt) messed with his technique. In contrast, Adam, who had gotten used to swimming in syrup and didn't have to think about it, had more consistent times.
- 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.
- 30 Rock
- 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.
- 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.
- Older Than Feudalism: The Gospels of John, Matthew, and Mark give accounts of Jesus walking on water. Peter is initially able to do so as well, but falls once he begins to wonder how this could be possible. (The point is that Peter starts to doubt how he can do it, which means his faith in Jesus is faltering.)
- 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.
- 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.
- For some particular reason, in a game where two or more players are fixed to a side of the screen, it's jarring for a player who's used to one side to have to use another. In most situations, there's no practical difference.
- Inverted in El Goonish Shive: When transformed into a girl, Justin initially has trouble walking because he tries to compensate for the new body... until told that he just shouldn't think about it, since the transformation gun already compensates.
- Later Elliot explains this while in the shape of a short girl. And, of course, immediately falls.
- In xkcd, Black Hat Guy invokes this by telling someone that it is Tongue Awareness Month.
- Spacetrawler. Emily deliberately invokes it.
Emily: Nice shooting. I wonder if you'd trip up if you stopped to think what each tentacle is doing.
- An episode of Beavis and Butthead had the boys forget how to urinate after thinking too hard about how to do it.
- Similair to the religious example above, a Running Gag in Looney Tunes is that a character can run (pun not intended) across water or even air just fine as long as somebody else doesn't point them at this fact.
- Lampshaded at least once in Tiny Toon Adventures - they can walk on air across a canyon as long as they don't look down.
- Happens to SpongeBob SquarePants 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.
- Bob from Bob's Burgers couldn't flip burgers properly after Teddy asked how to do it.
- 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.
- Some people use computers a lot, and then suddenly realize they can touch type. Then they have difficulty doing so as long as they think about what they're doing.
- 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.
- Related to schrödinbugs.
- 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.
- 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. After a certain number of repetitions the word itself will lose all meaning to you. Your brain still consciously know 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.
- This is even more unsettling when it happens with your own name.
- 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.
- 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 tough it's their own mother tongue. Might occur in other languages as well.
- Writers of fiction try their hardest to not let their readers realize they are reading something. Once readers stop visualizing the scene and remember that they're reading a book (usually due to clumsy phrasing, grammar/spelling mistakes, or something not making sense) their ability to enjoy the story drops drastically.
- 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.
- 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 your afraid of the dark, you'll run straight back to your room.
- Captain Haddock is shown to sleep on his tummy in Tintin and the Picaros