History Main / YourMindMakesItReal

* It's been suggested that Grigori Rasputin, the Russian monk who gained access to the court of the Russian Empire by supposedly being able to treat the Tsar's hemophiliac son, hypnotized the boy to "cure" him whenever he was injured. Rasputin's hypnotic powers were in fact recounted by others, even hardened men like some of the Tsar's ministers. Either Peter Stolypin or Sergius Witte who later recounted Rasputin's attempt to hypnotize him, which was very nearly successful.

** The evidence for conversion needs to be re-examined. It was originally based on preconceived notions about women and about VD.[[note]]Syphilis has a stage with lesions, then goes dormant for decades before re-emerging, causing insanity. Doctors didn't know this and thought you were cured when the lesions disappeared. A young man might catch it from a prostitute, years later pass it to his wife and of course "good people" didn't talk about this stuff. Creators who went insane due to this may have contributed to the perceived "link between creativity and madness" since no one knew it was VD.[[/note]] With no penicillin yet, doctors routinely prescribed ''mercury'' not just as a cure but a preventative. Mercury causes serious neurological damage including off-and-on paralysis, heart palpitations, deafness, blindness and pain. After Freud, doctors could now write those off as "hysteria". Hysteria became a garbage-can diagnosis; even a plain old orgasm was called a "[[https://jezebel.com/5914350/vibrators-and-clitoridectomies-how-victorian-doctors-took-control-of-womens-orgasms hysterical paroxysm]]".

* The whole {{Urban Legend|s}} about the [[UsefulNotes/{{Canada}} Canadian $100 bill]] smelling like maple syrup [[https://abcnews.go.com/blogs/headlines/2013/05/new-canadian-money-smells-like-syrup-melts-in-heat has prompted many people]] to actually smell maple syrup on the note, and sometimes on all new bills.

* The [[https://en.wikipedia.org/wiki/Morgellons Morgellons phenomenon]] has been listed by some experts as a disease that is spread through the Internet. Essentially it's a form of delusional parasitosis[[note]]a delusional disorder in which victims believe they are infected by parasites, usually accompanied by hallucinated physical effects.[[/note]] in which alleged sufferers claim to be infested with strange, organic fibers. Upon medical examination, it's almost always revealed these fibers are synthetic and the sores they complain about are the result of compulsive scratching; the catch is the "disease" continues to get ''worse'' once a person has self-diagnosed themselves with "Morgellons", creating a cycle of a [[ViciousCycle continually worsening condition caused by delusions which are caused by the continuing worsening condition.]] The only way to prevent it is by avoiding social "contamination" of Morgellons, [[BrownNote which is to say be unaware of the concept in the first place.]]

* A very simple vaudeville attraction works this way: You are in a "rotor", and then you get rotated head-over-heels. No, you aren't, it's your surrounding that is rotated, you are completely motionless. But if you fell for it, by now you are probably desperately clenching into your seat for not falling out, creating exactly the force that you'll expect (actio=reactio).

[[folder:Fanfiction]]

* This happens in ''Film/{{Gamer}}'' [[spoiler:at the end. "See this knife? Picture me driving it into your stomach. Imagine it and ''make it real''."]]

* ''VideoGame/{{Perimeter}}'': Totalitarian-sect-likeness of Exodus is traced back to first attempts of humanity to explore the worlds of The Chain. The violent reaction of the worlds themselves (termed "The Scourge") was tied to chaotic and fearful thoughts of inherently flawed humans, so the ritualistic practices, networked meditations and other means to keep reins were put in place. Without those, a high concentration of people (which Frames are) could never hope to survive. Other factions abolish this, one remains under the radar by going cybernetic hybridization way instead, the other embraces The Scourge.

* In ''Manga/JojosBizarreAdventureStardustCrusaders'', this is the power of the Stand "Death 13": it pulls its victims into a dream of an amusement park and then kills them while they're trying to figure it out. This actually gets used ''against'' it - anyone who survives the dream has their memories of it deleted, but Kakyoin thinks to scratch a message to himself into his arm, which allows him to realize what happened. In a later example in ''[[Manga/JojosBizarreAdventureStoneOcean Stone Ocean]]'', the trope is used to make people believe [[spoiler:that they are snails due to subliminal messaging]]. Yeah, didn't make all that much sense in context, either.

'''Morpheus:''' [[TropeNamers Your mind makes it real.]]\\

* In general, it's been proven that we're pretty easy to fool in this regard. A newer type of prosthetic limb channels physical feedback from the prosthetic to the stump. It doesn't take long for your mind to associate that stimulation with your prosthetic to the point that it feels like your actual limb. Also, VR can make you think a virtual image or a displaced image of something else is your real body, as demonstrated by such hilarious pratfalls as [[https://www.youtube.com/watch?v=IZ4IAxf7-sA this man]] taking a leap of faith VR game so seriously that he runs forward and launches himself straight into the television! Our brains are built ready for cybernetic upgrades.

* In general, it's been proven that we're pretty easy to fool in this regard. A newer type of prosthetic limb channels physical feedback from the prosthetic to the stump. It doesn't take long for your mind to associate that stimulation with your prosthetic to the point that it feels like your actual limb. Also, VR can make you think a virtual image or a displaced image of something else is your real body. Our brains are built ready for cybernetic upgrades.

* ''VideoGame/MaxPayne'' and its sequel have "dream sequences" which can kill you. Inverted somewhat in that they're caused by various NoOneCouldSurviveThat poisonings and injuries, so ''surviving'' them is the your mind makes it real.

* In ''Manga/JojosBizarreAdventureStardustCrusaders'', this is the power of the Stand "Death 13": it pulls its victims into a dream of an amusement park and then kills them while they're trying to figure it out. In a later example in ''[[Manga/JojosBizarreAdventureStoneOcean Stone Ocean]]'', the trope is used to make people believe [[spoiler:that they are snails due to subliminal messaging]]. Yeah, didn't make all that much sense in context, either.

* ''VideoGame/{{Stellaris}}: Spiritualists claim that consciousness begets reality, as proven by their 'science'. Considering they get easier access to Psionics than Materialists, there's weight to their claims.

* The result of two separate [[BattleInTheCenterOfTheMind spirit battles]] in ''Literature/{{Legend}}'' by Creator/DavidGemmell. When the acolytes' avatar has its back broken and Nosta Khan's is beheaded, the same things happen to their bodies.

** It's important to note that a defining characteristic of OCD is that the sufferer ''fully realizes that his or her compulsions have no actual effect''; no one with OCD actually believes that, for instance, washing their hands one hundred times is more effective than washing them once. Nor do they actually believe that something terrible will happen if they don't touch every surface in their room. Part of what makes OCD so painful is that the person is perfectly aware that what they're doing is totally irrational – but they feel compelled to do it anyway.

* In ''Series/TheOuterLimits1995'' episode "Mindreacher", scientists invent a new device that allows people to share dreams and cure people's mental problems. The protagonist and her boyfriend use the machine to enjoy a romantic dinner. However, after that, he goes into a coma. The machine is blamed, and the project is shut down. However, she accidentally messes up an implant injection (it latches on directly to her brain instead of a nerve in the palm), which allows to her mentally interface with anyone she touches. She interfaces with the boyfriend and finds out that he's allergic to strawberries, so when they ate them in the vivid dream, his body reacted as if he actually ate them for real. She "cured" him by convincing him that she has a cure in her hand and feeding it to him in the dream.

* In ''LightNovel/ACertainMagicalIndex'', Útgarða-Loki is a MasterOfIllusion, fitting for a mage based on the mythological giant illusionist. He's so good at this that he can make someone feel like he is on fire by showing him a picture of a fire.

* Subverted in ''LightNovel/ScrappedPrincess'', when the titular character enters a VR program to save her brother from being brainwashed, only to be promptly impaled by him when he fails to recognize her. There is a moment of shock, and then she slaps him in the face and continues to shout at him with his sword still stuck through her.
* In ''LightNovel/SwordArtOnline'', Virtual [=MMOs=] have pain inhibitors that prevent this from happening: if a player's pain inhibitor is turned down low or completely disabled, they can suffer actual bodily harm in the real world. The most extreme case is how the creator of the titular game deliberately turned his creation into a deathtrap by designing the virtual reality helmet to destroy the player's brain with microwave radiation if they die in-game or if someone else tries to remove the helmet from them.

* ''LightNovel/ALullabySinister'' features this. Falling into REM sleep drags students and teachers into what they call the Surrogate School. Dying there means you inexplicably die in your bed. Or wherever you fell asleep.

* In the Elseworlds tale ''ComicBook/SupermanAndBatmanGenerations'', the Guardians eventually reveal that the GreenLanternRing's weaknesses are all psychosomatic: regular [=GL's=] are weak to yellow objects because the Lanterns are told they are, while Alan Scott assumed his ring (which here is a ‘standard’ Green Lantern ring rather than the Starheart) was weak to wooden objects after a thug clocked him with a baseball bat his first time using it. Hal Jordan, who figured this out on his own, can use the ring without any such hindrances.

* In ''LightNovel/MagicalGirlRaisingProject Restart'', the main characters are forcibly trapped in a dangerous VR game and have to beat it to permanently escape. Dying in the game world triggers the victim's real body to suffer a heart attack, killing them. Other injuries don't affect their real bodies, however.

There's an old wives' tale which claims that if you die in a dream, you die for real. Although a potential mechanism is suggested in "Real Life" below, it remains not exactly clear how anyone could have determined this, [[FridgeLogic since the only witness would be unable to confirm it]] (unless you believe in [[SpookySeance spiritualism and he contacted you from the next life]]). Yet it persists, and a lot of people believe it.

** Illusion magic, obviously enough, works on this principle: as long as the victim doesn't know they've fall into an illusion, they will experience and suffer the effects. When Sarlama uses such a technique on Yakumo though, the fact that his HealingFactor isn't working allows him to understand he's victim of an illusion.

** ''Anime/DigimonAdventure'': Towards the end of the second StoryArc, Local Boy Genius Izzy figures out the [[TrappedInAnotherWorld Digital World]] is a world [[{{cyberspace}} made out of the data of Earth's network infrastructure]] and hence all the human protagonists are more than likely made of data in that world. Although he tells everyone to be careful in spite of this new development it doesn't sink in with TheLeader Tai and he starts acting like a jackass under the flawed logic that he'll somehow survive regardless of what happens. It takes Izzy telling him that he would more than likely die in both worlds if he messed up to put a stop to his nonsense. Unfortunately, this happens just after a member of the team is kidnapped and they're about to cross an electrified gate to go after her. He loses his bravado right there and the kidnapper gets away more or less scot-free, leading to a short term HeroicBSOD for Tai.

* In the [[Franchise/DotHack .hack series]], characters hit by the ''Data Drain'' attack within ''The World'' are usually sent into a coma in the real world, and are temporarily knocked unconscious at the very least.
** Some characters eventually realize that somehow their minds are taken ''inside'' the game world, experiencing it with their character's own senses instead of being at home with a headset and game pad. Naturally, they become deeply concerned about what's going on with their physical bodies, and what happens if their characters are "killed" in this state.

* In ''Manga/JojosBizarreAdventureStardustCrusaders'', this is the power of the Stand "Death 13": it pulls its victims into a dream of an amusement park and then kills them while they're trying to figure it out. In a later example in ''[[Manga/JojosBizarreAdventureStoneOcean Stone Ocean]]'' the trope is used to make people believe [[spoiler:that they are snails due to subliminal messaging]]. Yeah, didn't make all that much sense in context, either.
* Happens in ''Manga/NegimaMagisterNegiMagi'', during Negi's test to learn BlackMagic. He has to fight a phantasmic version of Evangeline formed from his memories inside his head; meanwhile Chisame has to take care of him, as wounds start appearing on his body as a result of the test, and a lot of BloodFromTheMouth.

* Trauma was a mutant introduced during ''ComicBook/AvengersTheInitiative'' who could become one's greatest fear. It's presumed that Trauma only gains power if his opponent fears what he's turned into, since he's been capable of turning into [[ComicBook/TheMightyThor Thor]], [[ComicBook/TheIncredibleHulk Hulk]], ComicBook/{{Juggernaut|MarvelComics}}, and several other people/creatures whose power levels are insane. However in a battle against the Hulk during the ''ComicBook/WorldWarHulk'' arc, it was discovered that if his opponents can control themselves during the fight and rein in their fears, he loses power.

* ''ComicBook/Robin1993'': The only reason Tim, a baseline human, can harm Johnny Warlock, a being that can easily shrug off the injuries caused by a pissed off Kryptonian, is that Johnny cannot disassociate him with the remembered pain of losing his hand to his own exploding gun after Robin damaged it in a fight while Johnny was still human. His own fear of Rob turns his powers against him when he's fighting him, which Tim absolutely takes advantage of and encourages by acting as though he's impervious to Johnny's powers as otherwise he and his allies would have been killed by the magic user long ago.
* In the graphic novel ''ComicBook/{{Shifter}}'', the main character finds out that, when using a surrogate (a creature which nervous system he has complete control over), the creature can be attacked and killed. If he doesn't eject in time, he will be killed, too.

* ''Literature/{{Paprika}}'' has a moments where the dreams and real life can't be told apart because of this trope... Both for the characters ''and'' the viewers.

* Creator/DavidCronenberg's ''Film/TheBrood'' starts off with a doctor whose therapy involves making mentally ill patients make their illness a physical one, which he would then cure, hey presto reverse placebo! The titular brood is the result of a woman who, as a child, had been physically and psychologically abused by her alcoholic parents..

* In ''Film/Goosebumps2015'', the explanation for why all the monsters in R.L. Stine's books actually exist is that, when he was younger, Stine was so lonely that he would dream up monsters to terrorize those that bullied him, until eventually his belief in them became so strong that they literally leapt off the page.

** Also averted in the training programs, [[UnwinnableTrainingSimulation which are designed to show you that you can die, but without actually killing you]]. For example, the "jump" scenario is considered impossible for a new red-pill to pass, as they cannot perform RoofHopping yet. Fortunately, the ground below is made to absorb most of the impact, only causing the trainee a fair amount of pain and wounding them slightly in the real world.

* In ''Film/{{Surrogates}}'', originally people could operate remotely-controlled surrogate version of themselves without any risk – no damage done to the surrogate could have any lasting effect on the operator. Naturally, someone finds a way to subvert this rule, and this is when the problems (and the plot) start. This is different from the original graphic novel, where there is no way to kill a person via his or her surrogate.
* ''Film/TheThirteenthFloor'' was sneakier: you enter a virtual world by possessing one of its inhabitants and if killed in this state, ''your'' mind dies. And not only that, but [[spoiler: the victim's mind takes over your body instead because it turns out the process is actually a complete mind swap. No one realized this because the real body usually remained completely unconscious during the process. Virtual death merely broke the connection and jarred the real world body with the virtual mind inside it awake]].

* ''Film/{{Virtuosity}}'' is not a straight example – the system is designed to train cops in combat situations, similar to the US Army's RealLife Force XXI program. The problem is that different people worked on different parts of the system – and didn't understand how Lindenmeyer's maniacal AI could abuse it. [[DevelopersForesight The Dev Team Thought of ALMOST Everything]] – they programmed in non-lethal simulations of being shot, bludgeoned and even ''bitten'' – but when Sid decided to try electrocuting someone, the poor chump's brain overloaded.

* Timothy Grant a.k.a The Brain Child from ''Literature/AppointmentWithFEAR'', is a boy whose troubling nightmares are so realistic, they actually manifest in the ''real'' world. At one point the Silver Crusader battles a fish monster materializing from a fountain, which suddenly vanishes mid-fight, and remembered he have Timothy Grant as one of his case studies. He then personally visits the Grants, interviewing Timothy if the boy had any nightmares recently; which Timothy replied "he had this really neat one about a fish monster coming out of a fountain".

* The main villain of ''Literature/StealerOfSouls'', Mordraneth the MasterOfIllusion, can summon illusions which looks so real, they can actually harm victims. For instance, his illusory SnakePit is perfectly capable of inflicting venomous poison on anyone that tried crossing it.

** In ''Literature/{{Maskerade}}'', the villain is killed in a sword-fight, but it was ''stage fighting'', and the sword is just held under his arm. However, he (and everyone else in the opera house) has been so immersed in drama and fiction for so long that it kills him because he expected it to.

* In the third ''VideoGame/HellgateLondon'' novel, a demon used a device which made the target relive his/her past in the dream, which will go horribly wrong and kill them, or make them go crazy.
* ''VideoGame/HiddenCity'' features plenty of magical phenomenon where characters' dreams and memories become reality.

* In ''Literature/{{Hyperion}}'', a cyberspace hacker's head explodes when he is exposed to a section of cyberspace inhabited by [=AIs=], which is normally inaccessible to humans. In this case, it's a completely real security system which causes his implants to boil his brain. When people are Mind Wiped during a network crash, however, that's the trope played straight.
* In Creator/StephenKing's ''Literature/{{It}}'' the "it" is an EldritchAbomination [[YouCannotGraspTheTrueForm whose true form cannot be comprehended]] and uses the worst fears of its victims to kill them. "It" preys on children because [[InvisibleToAdults adults]] are too closed minded to believe what they see. However, this is a two-way street - if the victims of "It" can convince it something is real, or have strong belief that something can hurt "It", then it affects "It" exactly as it should. One character manages to deal "It" serious injury by declaring that an asthma inhaler is battery acid and spraying "It" in the face.
* In the horror novel ''Literature/{{Jago}}'', the villain has potent psychic powers that appear to include {{Reality Warp|er}}ing. It's ultimately shown that much – although not all – of Jago's reality warping is all in the mind; his psychic power causes people to perceive reality as different, but the physical world is unchanged. At some points, individuals manage to temporarily see through the illusion to the more mundane reality beneath. However, when everybody present agrees that a thing is happening, and it's convincing enough that people die because they believe they've been killed, the distinction is largely moot, and Jago poses a genuine threat.

* Russian cyberpunk literary classic ''Literature/LabyrinthOfReflections'' by Creator/SergeyLukyanenko used a massive VR world... based on ''VideoGame/{{Doom}}''. Considering the state of the nigh-post-Soviet information network in 1991, that makes some sense.... The trick was a hypnosis program of sorts known as Deep that put the user in a trance-like state; the relatively limited visuals they were given were filled in by the brain's natural ability to add extra data (akin to limited side effects of sensory deprivation) and an immersive world was created. The trick was a very small, professional group of "Divers" who could bring themselves out of the trance-state at will, and interface with the system as it actually existed. Also there has been made a certain virus in the Deep that actually kills the users. And one that traps divers.

* In ''LightNovel/MagicalGirlRaisingProject Restart'', the main characters are forcibly trapped in a dangerous VR game and have to beat it to permanently escape. Dying in the game world triggers the victim's real body to suffer a heart attack, killing them. Other injuries don't affect their real bodies however.
* ''Magicnet'' falls somewhere between this and ClapYourHandsIfYouBelieve, depending on whether you view magic as a shared hallucination, or the product of an alternate reality that coexists with this one. Characters who truly believe that magic exists can and do get hurt by it, but a large amount of what occurs is shown to be just smoke and mirrors once characters deny it (e.g. a supposedly exploding plane engine turns out to be undamaged.)
* Averted in ''Literature/{{MARZENA}}'': Silly movies and video games, [[FateWorseThanDeath You can't die in a dream!]] Also if you die and fall in a comma, the Doctor can just bring you back to consciousness by stimulating your thalamus.
* In the ''Literature/MemorySorrowAndThorn'' series, by Creator/TadWilliams, the Dream Road is a metaphysical realm that is touched on by all thinking beings while they sleep, but that practitioners of [[FunctionalMagic the Art]] can enter intentionally, bringing others with them. Things that happen to one's mind on the Dream Road can and do affect one in reality, and in the most benign of circumstances it's possible for an inexperienced traveler to become "lost" and unable to return, leaving their body an EmptyShell. In less benign circumstances, there are ... things there that can actively destroy all but the most powerful minds. Such encounters are typically fatal ([[MindRape or]] [[GoMadFromTheRevelation worse]]) to the dreamer.

* In ''Literature/ThePendragonAdventure'', the territory of Veelox has a virtual reality system called Lifelight. It is initially stated that if you die during a Lifelight "jump", you simply wake up from it. However, once the Reality Bug is introduced into Lifelight in an attempt to make it less perfect and addicting, this trope gets taken to absurd levels. Not only do you die in real life if you die during a jump, but any injuries you get appear on your real body, even ''damaging your clothing''. And after the Reality Bug manifests in a jump as a giant shape shifting monster, it is somehow able to enter physical reality by burrowing down through the ground. Bobby even [[LampshadeHanging admits]] that all this violates the laws of physics as he understands them.

* The fourth ''Literature/{{Sorcery}}'' book has the Archmage's chamber, which is guarded by a corridor full of flames, that instantly incinerates anyone who tries to cross... unless they're told by Naggamanteh, the torturer, of the truth. The flames are actually an illusion; by believing its fake and ignoring it entirely, one can walk through the corridor unscathed.

* In ''Series/OneThousandWaysToDie'', there is a story about a woman who had persistent nightmares of a small, demonic imp strangling her. While she thought she was being strangled in her dreams, her physical heart raced till the point of a heart attack, killing her in her sleep.

* [[PlayedForLaughs Played for]] BlackComedy in an episode of ''Series/ElChapulinColorado''. The title character is called by a nurse in a hospital, where she's taking care of a couple of crooks who were involved in a shootout with the police. One of the crooks is fully recovered while the other isn't expected to make it past the night. Chapulín however swaps the medical records and begins messing with both crooks, telling the healthy one to just accept his death while trying to get the dying one to eat and do some exercises. At the end, Chapulín reveals he switched the medical records intentionally so as to try and convince the dying crook that he was healthy so he would get healthy for real. It works, but in turn the healthy crook becomes convinced that he's dying as well, and ends up dropping dead.

* ''Series/FearAndFaith'', a Creator/DerrenBrown special, uses a placebo coined as ''Rumyodin'' that is said to inhibit fear. It was eventually revealed that the participants' overcome their fear because they believed they could (with positive reinforcements from the placebo). It was even lampshaded, TheReveal reveals that ''Rumyodin'' is a SignificantAnagram of ''Your Mind''.

* In the season three episode of ''Series/{{House}}'' called "Airborne", Cuddy becomes sick during a flight from Indonesia to the US, having rashes, nausea and a fever, all because she believes she's been infected with meningitis from another passenger. Who turned out not to have meningitis at all.

** Another episode had a [[MasterOfIllusion master hypnotist]] (the second master hypnotist, not the first one) whose hypnotic illusions were so real that Jimmy bumped his head on an imaginary desk and got a real life bruise. The hypnotist used this power to cause people to die from illusions.

** ''Series/StargateSG1'' episode "Avatar": Teal'c gets trapped in a VR simulation that shocks him every time he dies in the game. While the simulation itself can't harm him, the continual shocks force his body to produce extra adrenaline, which eventually ''can'' kill him. He's trapped because in real situations Teal'c would never quit, and so the simulation disables the abort option. It turns out to be even worse than that: the simulations aren't pre-programmed, but work off the sim runner's mind. Teal'c will never quit, never surrender... He also believes, at the time, that [[FailureIsTheOnlyOption no matter what, they can never fully defeat the Goa'uld]]. Meaning not only can he not just hit the off button, but whenever it seems like he's going to win [[TheComputerIsACheatingBastard something new pops up]], kills him, then the sim restarts ''and gets harder still.''

* In ''Series/StarTrekVoyager'', in the episode "[[Recap/StarTrekVoyagerS2E23TheThaw The Thaw]]", the crew of the Voyager finds a machine where the surviving members of a species whose planet was struck by a natural catastrophe were placed in stasis, and their brains were wired into the machine, which created an artificial paradise inside it. Unfortunately, when the crew looks inside the program uploading Harry inside it, they find out that inside there is an... entity, called [[MonsterClown "The clown"]], who keeps the dreamers trapped inside. When the crew tries to disconnect them from the machine, it threatens to put one of them on the guillotine. He does, and the dreamer's body dies of an heart attack.

* Series 2 of ''Series/{{Torchwood}}'' had a villain who only existed in the altered memories of the staff. He faded from existence when they used the humorously named drug {{retcon}} to erase their memories of the time he'd been interacting with them (all of two days, though he himself had retconned the staff's memories to include him further back. It only required 2 days erasure to get rid of him, though, because obviously the memories he put in or stirred to the surface were only that much fresh).

** A more serious version is the episode "[[Recap/TheXFilesS03E17Pusher Pusher]]", where a man has the ability to ''talk people into'' killing themselves in various ways. Most of the time, it's by making them do something self-injurious, but at least one of his victims dies from being given a graphic verbal description of a heart attack, and then suffering the same.

** It's no coincidence that two of the most common "curses" which folklore alleges can be inflicted via supernatural means are "breath stealing" and impotency. Directed against someone with even a minor predisposition to allergies, asthma, or an active respiratory infection, the sheer anxiety of ''believing'' their breath has been "stolen" could bring on an attack of breathing difficulty. Likewise, performance-anxieties exacerbated by an impotency "curse" may impair a male believer's capacity to relax, to such a degree that the parasympathetic reflexes of erection can't take place.

* ''TabletopGame/DungeonsAndDragons'' has several illusion spells (most notably of the Shadow sub-school) that function this way, e.g. ''[[http://www.d20srd.org/srd/spells/shadowConjuration.htm Shadow Conjuration]]'' and ''[[http://www.d20srd.org/srd/spells/shades.htm Shades]]''. These spells create illusory constructs or facsimiles of spells from other schools, and have reduced effects on characters that successfully "disbelieve" them. Naturally, they always have this reduced effect on objects and creatures with low intelligence, such as constructs.
** Some Phantasm spells, such as ''Phantasmal Killer'' and ''Weird'', make you save or die upon failing the roll to disbelieve, doing nasty damage even on success. Annoyingly, ''Death Ward'', which protects against other spells that make you save or die, won't protect you against this because it's an illusion based on fear, since ''Death Ward'' protects only against direct, external magical energies that cause death, while these illusions essentially rely on tricking the target into killing itself. 5th edition alters both so that, while they're not instant death, their torment lasts longer, Frightening the target(s) and damaging at the end of each round until it's over or they ''finally'' make their save to disbelieve it.

** One of the first ''Literature/{{Dragonlance}}'' game modules had the player characters travel into a living nightmare to end its hold over an elven kingdom. Many of the monsters the players encounter are in fact creations of the dream, and can be made harmless if players state they don't believe in them. Unfortunately, quite a few of those monsters are very real, and will attack the players anyway, and it's very difficult to tell the difference.

* ''TabletopGame/{{GURPS}}'': The "stigmata" enhacement to the Illusion advantage from ''GURPS: Powers'' can cause small amounts of damage to the target, but only to the point that he falls unconscious from the wounds.
* ''TabletopGame/MageTheAwakening'': This can happen to you in with the [[DreamLand Astral Realms]]. Under normal circumstance, attacks in the Astral Realms don't harm health, but instead reduce Willpower (a person's reserve of mental and emotional strength). If a person loses all of their Willpower (not necessarily from being attacked) they return to the waking world, unable to maintain their Astral self and completely emotionally drained, but otherwise unharmed. There are however ways in which the person can be damaged or destroyed ''mentally''. For example, being attacked by an ideology until the person's identity is completely buried beneath fanaticism, being drawn into the hold of an insanity realm until one's personality is utterly destroyed from that insanity, or going to the Dreamtime unprotected, where one's mind will be completely washed away by a consciousness which is incompressible to and uninterested in human perspective or individuality (essentially, your sense of identity is lost among the thoughts of something which has existed before there was life). In these cases, the body becomes a completely healthy vegetable. There are also beings capable of inflicting actual damage from the Astral Realms, though this is more to do with magically being able to target your body directly rather than because Their Mind Makes It Real.

* An odd example in ''VideoGame/{{Bloodborne}}''. Certain enemies gain extra attacks when you have a high level of [[ThingsManWasNotMeantToKnow Insight]], because you can understand them. Below the Insight threshold, the attacks won't appear as you WeirdnessCensor them out of existence.

* ''VideoGame/CommandAndConquerTiberianDawn'': in the final cutscene for the Nod campaign, a group of hackers are shown plugging themselves into machines that sends them into a virtual reality world, where they try to hack into GDI's ion cannon control system in order to gain control of their orbiting KillSat. Two of the hackers get zapped by the defenses in the virtual world, and are shown dying in the real world too, but the third one manages to succeed.

* Central to the gameplay in ''VideoGame/{{Dystopia}}'', where players work with each other between Meatspace (the solid world) and Headspace (Cyberspace). Headspace obstacles such as encryptions, passwords, or [=ICEs=] (Although the regular [=ICEs=] don't damage the player, and GREEN [=ICEs=] only forcibly jack the player out with an EMP) are ''physical'' to the player's avatar, and entire fights wage on in Headspace. If one ''dies'' in Headspace, they are yanked back to their physical bodies with [[InterfaceScrew disorientation]] and bodily damage (HP loss). It is also possible to sneak behind a jacked-in player in Meatspace and kill them. The player's avatar is told that their Meatsack (body) is taking damage, and death simply deletes the Headspace avatar in the middle of whatever it was it was doing.

* In ''VideoGame/FatalFrameIII: The Tormented'': Rei, Miku and Kei travel into the House of Sleep when they dream. If they lose all their spiritual health in the dream-world, they are confined there forever; leaving nothing in the physical world but a bunch of scorch-marks.

* ''VideoGame/{{Immercenary}}'' is set in a virtual reality game where much of humanity is trapped, with the player character being somehow projected into the it from the past. Being [[DeadlyEuphemism crashed]] in the VR game is not immediately fatal, but apparently it does cause shocks to the system that eventually can result in death (as is shown to a predecessor of the player in the opening cinematic). Whether this is an intentional feature of the system or whether it is a side-effect of the time-projection technology is never stated. Late in the game, the player learns of an arguable inversion: characters crashed by the player are, due to the player's unorthodox presence in the system, misread by the controlling AI as having been disconnected from the game; the AI then responds by shutting off life support. Thus, characters crashed by the player die because the AI's mind makes it real.

* ''VideoGame/TheMatrixPathOfNeo''. Since it's a ''Matrix'' game, this is in effect full-force.

** Parodied with during one boss battle (which, like much of the game, takes place in the psychic landscape inside someone's mind), one of your fellow interns, who has been taken hostage, shouts that you need to save them because if you die in someone's mind... you ''[[PottyFailure pee your pants]]''.

* ''VideoGame/{{Ripper}}'': The killer known as the "Ripper" has the ability to kill anybody who once played the online game ''Ripper'' (the "Ripper" is one of the original players, the protagonist has to figure out which one of the surviving players it is). The Ripper's ability takes the form of a "software rewrite" of the victim's "brain software": the hormonal and electrical layers of the human brain. When triggered (through use of a BrownNote telephone call), the fluid and air pressure within the victim increases rapidly causing them to violently explode. The protagonist has to have his own "software" modified with an immunisation so that the Ripper can't use the "long range doohicky" any longer (he is still vulnerable if the Ripper chooses to attack him "face to face" in the virtual world).\\

Later, the Ripper calls all of the surviving characters into the virtual world, and demands the protagonist choose who they think it is. The protagonist at this point has armed himself with a single-use "virtual weapon" in the form of a pulsing orb of energy. Each of the characters make their case to the player, and the player must use the virtual weapon on the character they think is the Ripper, presumably killing them, as the ending narration is spoken in the past tense. Choose badly and not only have you killed an innocent person, the Ripper attacks the protagonist directly and kills him as well.

* ''Webcomic/AliceAndTheNightmare'' is one big deconstruction of the DreamStealer trope, specifically because of this trope. Residents of the Dream World, basically Wonderland and the Looking Glass territory, steal dreams from sleeping humans for use in their modern-day technologies and to stabilize their world, while fighting off eldritch nightmares that can manifest in dreams and Wonderland. This is exactly as dangerous as it sounds; the humans on both sides can utterly screw each other over in a dream. Not only do dream harvesters have a disturbingly high death rate, but screwing around with a dream too long may cause the sleeping human to develop a psychic affinity, accidentally teleport themselves into Wonderland, and literally mutate into their worst nightmare that will hunt down Wonderlandians until it is put down by the firing squad.
* That's how dream world can be dangerous in ''Webcomic/{{Archipelago}}'' - if you get injured in there, and a specialised healer doesn't treat you on time, the scars, blinded eyes and ''lost limbs'' become real.

* ''Webcomic/{{Paranatural}}'': Spirits who have bonded with humans can pull them into a "spirit world," a sort of shared hallucination where the pair can communicate with a heightened perception of time, so that it seems like TimeStandsStill. While this is all in the human's mind, if the spirit were to, say, bite the human's head off, the human's head would be bitten off in real life.

** [[http://scp-wiki.net/scp-896 SCP-896 ("Online Role Playing Game")]]. Anyone who plays SCP-896 will have their real life attributes increase to same degree that their in-game attributes do. However, if one of a character's attributes rises too high above the others, the player's attributes decrease. The Foundation developed a harmless version of the game because it was publicized too heavily to just destroy, but in usual FridgeHorror fashion Foundation employees have [[TheEndOrIsIt very recently been barred from playing the harmless version too]].

* ''WesternAnimation/TheLoudHouse'': In the MusicalEpisode "Really Loud Music", Luna begins to worry if the song she wrote won't be a song the whole world will love; it's at that point she starts hearing her family burst into songs out of nowhere (Lola singing a show tune, Lana performing a toilet jam, Lisa doing a rap, Lori and Leni singing a love ballad, and so forth). [[InnerThoughtsOutsiderPuzzlement When the first three claim they weren't singing at all]], Lisa concludes that Luna is hallucinating her family singing, because her brain is trying to find the right genre for her song thus brings said genres to life in the form of each family member.

** {{Double Subver|sion}}ted in the episode "[[Recap/TheSimpsonsS23E16HowIWetYourMother How I Wet Your Mother]]", which parodies ''Film/{{Inception}}'' with Professor Frink's device that allows Homer's family into his dreams. When the family are falling down a cliff, Marge assures them that if they die in the dream they'll just wake up, but then Frink interjects, saying that since he didn't update Adobe Acrobat they'll actually die for real.

** There is also its EvilTwin, the Nocebo Effect, which works exactly the same as the Placebo Effect except with things the patient believes will make them ''worse''. For example, in double-blind studies, patients given what they told was anti-cancer medication tended to have their hair fall out... even if the medication in question was sugar.
* Conversely, the opposite effect can occur when someone suffers from extreme depression, or complete loss of hope. Someone with failing health could increase their lifespan and quality of life if they believed something that gave them hope (not just "a positive attitude"), but those without hope will often succumb to their ailments, especially if they have been dealing with them for a long time. Teddy Roosevelt was considered to be the pinnacle of stubborn toughness, but when his son died, he fell into despair and died shortly after.

** Speaking of VR, there is a phenomenon called "phantom touch" in which some individuals will "feel" themselves being touched in VR. Thought to be related to phantom limb syndrome, sensations vary from light tingles in the touched area of one's avatar (even long ears and tails can be felt in some avatars) to full on "phantom sense" in which some may even imagine temperature changes or smells from certain objects or environments to the extent that it's almost real to them.
** And for the matter, unrelated studies and effects can offer interesting insight in to how much our brain fools us. During one brain surgery, one patient felt the presence of a non-existent person 'nearby'. Follow-up tests/cases shows that a part of the brain responsible for the sense of personal location within 3d space was being triggered and manipulated resulting in people sensing and seeing what amounts to classical depictions of dopplegangers.

** This applies to colors in general. What we think of as an object's color is, in fact, the part of the visible electromagnetic spectrum that the object ''doesn't'' absorb from the ambient light (white means the object reflects all light, black means it absorbs all light, reflecting nothing). In fact, each brain processes colors differently, so no two people see the same color exactly the same (although, most can, at least, agree that green is green, unless they're colorblind). It's possible for a skilled hypnotist to confuse someone's brain and shift the color perception, resulting in that person perceiving yellow as red, for example, and red as black. Creator/DerrenBrown has done this to a student once, resulting in her wondering who re-painted her car, while her friends look at her in confusion.

* [[https://en.wikipedia.org/wiki/Hypochondriasis Hypochondria]] is another example. It's a condition where a person becomes paranoid that they're suffering from a chronic or deadly illness, despite nothing being wrong with them. They get many different types of medical test done and told nothing is wrong, but they refuse to accept the positive results. This results in heavy anxiety, panic attacks, and over all bad stress which have symptoms common with some major illnesses which further convinces them something is wrong. And since too much stress is unhealthy, [[SelfFulfillingProphecy the person eventually causes a real illness to happen.]]

* Art is basically made by arranging lines, colors and shapes in such a way that the brain falsely perceives it as looking like the intended object(s) instead of the assorted lines and marks that it actually is. Most art in general works like a complex optical illusion.

* ''Wiki/SCPFoundation'':

* In ''Film/{{Hook}}'', the Lost Boys' feast of imaginary food doesn't become real for Peter until he begins to believe in it.

* Sarge from ''Machinima/RedVsBlue'' explains this to Grif and Simmons when showing them the holographic simulation room.

** One of the phenomena observed by the Foundation is [[http://www.scp-wiki.net/scp-1237 a peculiar type of brain-wave pattern found in some humans]]. People capable of so-called "epsilon-wave sleep" will find that things they have dreamed about come true.

* In the Elseworlds tale ''ComicBook/SupermanAndBatmanGenerations'', the Guardians eventually reveal that the GreenLanternRing's weaknesses are all psychosomatic: regular GLs are weak to yellow objects because the Lanterns are told they are, while Alan Scott assumed his ring (which here is a ‘standard’ Green Lantern ring rather than the Starheart) was weak to wooden objects after a thug clocked him with a baseball bat his first time using it. Hal Jordan, who figured this out on his own, can use the ring without any such hindrances.

* Trauma was a mutant introduced during ''ComicBook/AvengersTheInitiative'' who could become one's greatest fear. It's presumed that Trauma only gains power if his opponent fears what he's turned into, since he's been capable of turning into ComicBook/TheMightyThor, [[ComicBook/IncredibleHulk Hulk]], Juggernaut, and several other people/creatures whose power levels are insane. However in a battle against the Hulk during the ''ComicBook/WorldWarHulk'' arc, it was discovered that if his opponents can control themselves during the fight and rein in their fears, he loses power.

* Both subverted and realized by ''Film/{{Inception}}'', where any physical damage in the dream world, even killing yourself, has no physical ramifications in the real world; but mental manipulation within the dream world has mental and thus physical ramifications in the real world.