Mental Picture Projector

"" Turn off the screen and let me project my thoughts!""

- Mike Nelson imitating a Local Yokel, Mystery Science Theater 3000 "Boggy Creek II''

"" He's thrashing around while he's having his dream, and his dream can be seen on the monitor screen!""

- MC Mothmaster Murf "Amazing Robocop Rap"

Speculative Fiction's answer to literally seeing what's on your mind via a form of an Applied Phlebotinum Machine that hooks up to your forehead and projects your thoughts in visual form onto a screen for all to see.

A cousin trope of Magical Security Cam. Compare Mind Probe, where this technology is explicitly used for torture.

Anime and Manga

 * In Mahou Sensei Negima, Jack Rakan has a machine that turns his memories into a film reel, so that he can go through the Backstory without having to explain everything himself.
 * Lupin III gets hooked up to one during a Non-Serial Movie. The result, much to the surprise of the Mad Scientist, is.
 * In Love Hina, Kaolla Su builds a device so that people's dreams may be put on the television. Obviously, Keitaro suffers because of it.
 * Trinity Blood had one of these at the Vatican's disposal, but it was very painful for the witness and showed only picture, not sound.
 * Cowboy Bebop had the 'Alpha Catch', which showed the last thing a nearly-comatose bounty-head saw before he was hurled out a window.

Comics

 * Fantastic Four #27 has Reed build a "Thought Projector" that creates images based on the thoughts of the wearer. It is brought out of storage in #126 so Ben can have a Flashback to their Origin Story. Returned again so that Reed could communicate with a coma patient in an issue of Marvel Knights 4.
 * In Amazing Spider-Man #39, The Green Goblin used a machine to project images from his brain of his past battles with Spider-Man.
 * Kryptonian Thought Beasts used to do this in a Silver Age Superman story, showing what the person they were near was thinking on their triceratops-like forehead shields. They showed up repeatedly in Krypton stories. Often as not, the image depicted the viewer's fear of getting stomped flat by the hulking thought-beast.
 * Kryptonian society also rendered artists moot with their device that allows painting by thought.
 * Calvin and Hobbes, Aliens abduct Calvin and hook his brain up to a computer monitor where they bring up all of Calvin's (incorrect) math knowledge and delete it from his cranium.

Film

 * Batman Forever: The Riddler has a device that can do this. He sees that Bruce Wayne is thinking about bats and concludes that Bruce Wayne must be Batman.
 * Futureworld (sequel to Westworld) had a machine that showed the thoughts and dreams the female protagonist was having.
 * Lewis's Memory Scanner in Meet the Robinsons.
 * WALL-E: When the Captain wants to see what happened during EVE's expedition, he sticks a miniature projector on her head and watches the playback. Justified, since she is a robot.
 * The chair that can monitor RoboCop's dreams as mentioned above.
 * Mom and Dad Save The World
 * The Memory Eraser from Flash Gordon.

Literature

 * One old short sci-fi story featured an auditory equivalent, allowing two people with electrodes hooked up to their skulls to communicate thoughts directly. IIRC, one end was designed to receive, the other to send thoughts. Several basic tests were run to make sure the thing wasn't a fluke or a placebo leading to an additional receiver being installed for confirmations. The story ends with a bit of a twist when they try hooking one receiver end up to the sending end directly in a loop. The scientist on the other receiver looks terrified and rips them apart moments afterward. Apparently, he heard the machine itself start to think...
 * A story titled "Into the Sunset" by D.C. Poyer had the religious dictatorship that'd taken over the U.S. build a machine that could detect people's thoughts, although no display was involved. If they thought unauthorized things, the machine would automatically punish them -- with a power surge that wiped the brain completely, effectively killing the victim while leaving his or her body alive. Unauthorized things, of course, included wanting liberty and justice. Then the dictatorship installed the mind reader at all entrances to government buildings....

Live Action TV
"House: Anyone ever tell you you are a MASSIVE buzzkill?
 * That's So Raven, "Vision Impossible": Raven's Clip Show er... I mean thoughts are projected onto a screen via a fancy machine.
 * In The Sarah Connor Chronicles, John Henry, a T-888 Terminator hooked up to an advanced AI, has screens that project images related to what he's thinking about.
 * There was an episode of Stingray where King Titan interrogated Troy Tempest using such a machine, without Tempest knowing it.
 * Quatermass and The Pit (TV and film versions) has a thought-visualising machine called an "optic encephalograph" that shows racial memories of Martian genocide.
 * The Prisoner episode "A, B and C" involves a machine that can read Number 6's dreams and memories, but by the end of the story he is controlling the images.
 * Done many times on Doctor Who, most famously in the Narmful "no, not the Mind Probe!" moment in "The Five Doctors".
 * Other notable examples include the first Doctor being interrogated, but because he's being flippant, the screen shows only random objects, and the second Doctor's trial in "The War Games", wherein he mounts his defense by using thought projection to show images of the great enemies he has fought, including the Cybermen, the Daleks, and... The Quarks. Since the Quarks were a one-off and markedly crap villain—and not even the proper enemies in that episode anyway (they were just service robots working for the Dominators), it has become something of a running joke in the Expanded Universe that the second Doctor has a weird and inexplicable Quark obsession.
 * Another example occurs when the Second Doctor creates a mental projector with the scanner to explain to Zoey how traveling in the Tardis can be dangerous by showing her clips from "Evil of the Daleks".
 * Stargate SG-1 "Out Of Mind" A machine is used to project holograms of SG-1's Clip Show memories. Like anything that shows up on Stargate, it makes reappearances in several subsequent episodes.
 * Red Dwarf: "Gunmen of the Apocalypse" projects Kryten's "dreams" onto a monitor.
 * Again in "Back In The Red" when a machine is used to probe the crew's minds to obtain evidence in their hearing.
 * Farscape: the Aurora Chair is a sadistic version.
 * One episode of House had one of these. I kid you not.
 * At least everyone else in the episode had a realistic level of skepticism. It's like only House realizes it's a TV show.
 * A bit of context: The patient was having unexplained seizures and out of body experiences. After running every diagnostic they can think off, they haul out a highly experimental "brain reader." They first show the patient a series of pictures, so the machine can analyse how her brain processes pictures. Then, when they ask her to think of one particular thing, they get a very fuzzy, very basic outline of her mental image. So, it's not exactly making a 3D hologram of her thoughts, but it seems plausible, maybe Twenty Minutes Into the Future.
 * The best part was everybody's reaction to Foreman's reasonable skepticism:

Everyone Else Present: YES."


 * On I Dream of Jeannie, Doctor Bellows tells Major Healey they'll be monitoring his dreams while he's in the shuttle (presumably in terms of brain activity), he assumes it's this trope, and advises not to construe anything from his more interesting dreams...
 * Used in Power Rangers Operation Overdrive to facilitate a Recap Episode / Clip Show. Handwaved in that the guy whose mind they're scanning is.

Newspaper Comics

 * Mandrake the Magician frequently does this as a means of painless interrogation. He hypnotizes the target to sit still and then literally causes their memories to appear on a wall like an old fashioned movie projection.

Tabletop RPG

 * Call of Cthulhu (tabletop game) supplement Cthulhu Now, adventure "Dreams Dark and Deadly". A dream research institute develops technology to read the dreams of sleepers, and can project them onto TV screens so others can watch them.

Video Games

 * In Earthbound, after completing one of the late-game Sanctuaries, Ness's thoughts are projected and visibly scroll across a neon wall where he begins asking himself about his journey and his progress. This is one of only two times that Ness has dialogue in the game.

Webcomics

 * This Perry Bible Fellowship comic.
 * The potential use of one that can turn the victim into a mindless shell of himself is a looming threat to the cast of The Omega Key.

Western Animation

 * Hi Hi Puffy AmiYumi, "Spaced Out": The Banana Aliens have our heroes Strapped to An Operating Table and use a "Brain Probe" to project their thoughts onto a monitor. Ami thinks about a Sugar Bowl inhabited by bunnies. Kaz thinks about swimming naked in a pool of money. Yumi thinks about beating the pulp out of their captors.
 * In a Clip Show episode of The Simpsons, Kang and Kodos used one of these on the Simpsons in order to judge humanity.
 * In the early 90s tie-in book "Bart Simpson's Guide To Life", Bart's dream bedroom includes a Video Dream Recorder.
 * In Aaahh Real Monsters, the Gromble uses one of these to view his students' scares and grade them. The projection is done through the student's eyes, even if they're away.
 * Batman: The Animated Series "The Strange Secret of Bruce Wayne" had Hugo Strange connect Bruce Wayne to such a device and thereby deduce that Bruce must be Batman.
 * It sort of helped matters that he got Bruce to all but say "I'm Batman" in a therapy session, while the monitor showed a black-gloved fist clenched over the Bat Signal.
 * Buzz Lightyear of Star Command "Star Smasher", Zurg uses a "Mind Probe" is retrieve plans for a trash compacter from the mind of one of the kidnapped LGMs. The plans appear on a computer monitor.
 * An audio version is used on SpongeBob SquarePants. It breaks when resident Cloudcuckoolander Patrick uses it.

Real Life

 * Researchers at the University of California, Berkly, are starting to figure out how to do this with the waking mind, by having a subject watch a video, recording what happens in their brain, then trying to re-translate it into video. While crude (you can find examples with a carefully worded search on certain popular search engines), the technique is still in its infancy, and could very well lead to dream mapping in twenty years or so...