what forms of torture do not leave any physical marks or evidence

lest there be confusion as to why I’m asking, here is why. my understanding is one of the goals of torture is to intentionally deform someone then send them back home. that way they serve as a warning to others. someone passes off the dictator so you break his bones, cut his eyes out, etc then send him home so his community can see what happens to rebels. this is why crucifixion was done in public places in Roman times.
but in the age of ubiquitous camera phones and international journalism this can and hopefully would backfire. torture would just make more powerful international nations oppose your regime since most wealthy western nations oppose torture, at least verbally, and possibly serve as a rallying point for domestic opposition. so torture that leaves mental damage but no physical damage would probably grow.
so what forms of torture do not leave physical marks? all I can think of is sleep deprivation, stress positions, electric shocks and simulated drowning. anything else?

Psychological torture.

Positional/Compressive asphyxia, provided the object that applies force to the torso is not so rigid/firm as to cause local bruising.

there is chemical torture too. forcing the extracts of spicy peppers into people’s noses, eyes, mouths, etc. i don’t think that leaves bruises.

Of course, bruising goes away after a while.
Did you mean any marks at all, or no permanent scars.

Well put. One of the alleged permanent results of one of the alleged legal alleged techniques allegedly used in Guantanamo is the arthritis that results from being restrained in difficult and painful positions for many hours a day, for many days, or sleeping on a cold hard concrete floor.

You can cause someone a great deal of physical pain without leaving any marks. Twist someones arm behind their back the right way and hold it for example. You can also press down on someone’s upper back with a blunt, hard object in a way that is difficult to endure for very long but doesn’t cause any real damage. There are many possibilities.

Waterboarding doesn’t cause any physical damage by itself either and that is reputed to be among the most terrifying tortures of all. Neither do most other forms of water torture.

I have never heard that a common goal of torture is to cause damage to serve as a warning. I don’t believe that is true for most reasons for torture. There are only certain situations where that is a main goal (criminal organizations for example). In those cases, the victims may have something like their fingers cut off to serve as an obvious warning to others but I don’t consider that to be the same as torture. I think it falls more into the revenge and psychological warfare category.

“It’s like a kind of torture, to have to watch the show.” -Statler and Waldorf, on “The Muppet Show”

Of course, upon seeing the thread title, my mind immediately jumped to smart-alecky answers like “Force them to watch [bad TV show]” or “Make them listen to [bad music].” While this is 98% a joke answer, I suppose exposure to unpleasant sights or sounds would arguably count as “torture that doesn’t leave any physical marks.”

I used to hold my sister down and let a toad pee on her face, never left any marks. I don’t know why she didn’t get warts??

Isn’t that how the US got Noriega to surrender? I heard they played AC/DC or something similar until he came out of the church he was holed up in. (I think I could take AC/DC for awhile, but if they started in with the Carpenters or the Starland Vocal Band, I’d come right out. I can’t imagine having to listen to “Afternoon Delight” on a 24/7 loop.)

“Need answer fast”?

In the UK there’s a sort of running joke about Police wrapping people up in duvets and throwing them down stairs which is supposedly how they extracted confessions from people in the ‘old days’ without leaving evidence such as bruising or cuts. However I don’t know if there’s a grain of truth in it.

Well yes of course…do you think they would admit to being wrapped in a blanket with a French name…please…I’ll sign the confession

to the OP, strikes with semi soft but heavy objects are good examples too, like a fabric bag with 10 pounds of sand in it.

Marriage

hence why I said verbally. torture wasn’t even banned as a method of interrogation until 1936 in the us. but with Syria as an example, when it got out that the government was torturing kids that started an international backlash.

Wasn’t there some group who made people watch the megabomb movie “Gigli”?

The legendary Mike Roykoonce claimed that Chicago Police interrogated prisoners by slamming the city’s huge phone books repeatedly down on the prisoners’ heads. He said this left no marks but made the prisoner feel like his spine had been compressed into a small cube. I have no idea how true any of that is.

Or Ginger Beer/Coca Cola

If I wanted to torture someone without leaving any evidence here’s what I’d do. First, restrict the individual’s hands in a way that he can’t reach his back. (Handcuff in front or to a wall or chair) Next, pour a handful of itching powder down the back of his shirt. Guaranteed to make him sing like a canary. And with a few exceptions from bleeding hearts you couldn’t even really call this torture.
We have ways of making you talk!

Torturing someone the victim cares about in front of them.

Rape; often combined with the above.

Sensory deprivation.

Sleep deprivation.

Starvation.