Hysteria: When do they start seeing what's not there?

You are conflating hallucinations (seeing things) with the hysterical reaction you are describing which is believing you have physical symptoms. What we typically think of as hysteria does not include visual or auditory hallucinations, only perceived physical symptoms.

Well, to start off, there is no longer a mental state officially classified as "hysteria". It's considered an obsolete term, and back when it was a thing, this isn't what it was intended to describe. Secondly, three children convincing themselves of something that isnt there, and scaring themselves into the bargain, would be considered completely normal, and has no specific term attached to it. Anybody ''could'' do this under almost any circumstances, and how long it would take, and how convinced they would be, are essentially unpredictable. The bad news is that there is almost no real research you can base this on, but the good news is that since it's so variable and unpredictable, you can basically write it any way your story requires.

Victor Douglas said:

Well, to start off, there is no longer a mental state officially classified as "hysteria". It's considered an obsolete term, and back when it was a thing, this isn't what it was intended to describe. ...

Click to expand...

Though we shouldn't, we do still use the term in the US. Hysteria is a terribly sexist term in that it originated when the uterus was blamed for certain psychiatric conditions and one might even be given a hysterectomy to treat anything from a real psychiatric condition to gawd knows what.

However, this got me thinking and I remembered the Miracle at Lourdes and all the events tied to it from people believing they've been cured to people who believe they see the Sun move unnaturally (there are various versions). There are videos on Youtube claiming to be of these weird events. I don't find the videos convincing, but other people claim to have seen the Sun do weird things. So mass hysterical hallucinations do occur.

I take my tunnel vision back in which I was only thinking of contagious somatic symptoms.

Wiki has some interesting examples.

ForeverYoursCaffiene said:

I'm in the US and hysteria is pretty common to hear, especially with being used by politics right now.

Let me explain the MC and make sure this is plausible. He had trauma in his life, and his playing can cause him to fight imaginary creatures. Sure, most of the time it's pretend, but other times it feels so severe and real. In the sequel, he's his normal self until he revisits something he fears. The boys make him fear of a possible ghost they believe to be real (but they have never seen it themselves). The MC sees it while they don't (for now it's just him). So, I'm wondering if that means mass hysteria of all who believe can make some have hallucinations, while it's possible the MC's past trauma awakens and causes an onset of hallucinations/delusions.

Click to expand...

Sounds to me like the two kids are pretty normal, and the mc is predisposed to having a psychotic episode by his PTSD.

Does that fit?

ForeverYoursCaffiene said:

I can see your point. It's like telling ghost stories at a campfire, and then a branch breaks and scares everyone. I would find that normal for their current state of fear.

If there can't be a group of these three kids seeing the same thing, then I think my MC can be argued to have delusions that come out of fear due to prior psychological trauma. He would see things that they wouldn't.

Click to expand...

Do you need to have a formal name for it? I'd say it sounds about right, just as you describe it:"It's like telling ghost stories at a campfire, and then a branch breaks and scares everyone."
No need for calling it PSTD or 'psychotic'.
The two kids start off just teasing the third, who, because of his past history, reacts more strongly than they expected. His visualization of the ghost as 'real' gets to them, and they start reacting to that, because they've more or less talked themselves into being susceptible to ghosts. All it would take is one kid with a vivid imagination or memories, if that boy is the kind of charismatic kid who tends to be a leader, have the cool ideas, etc, that others sort of follow along with.

Another fun fact: people can develop PTSD from their own psychosis.

Shared delusional/psychotic disorder is probably what you're looking for in regards to his friends.

Reminds me of that really horrible Slenderman stabbing case that occurred a couple years ago.

EDIT: neandermagnon makes a good point, and I forgot to mention that most professionals will not give an official PD, schizo-spectrum, or mood disorder diagnosis until at least the late teens. Kids are tricky. Kids with early onset symptoms are very, very rare and also very tricky. I suppose I'm on a bit because it's just really important to accurately portray any kind of mental illness, especially anything to do with psychosis. I think that's the point I've been trying to make.

Anyone can see things that aren't there in the right circumstances. There was an interesting article in the New Scientist a while back about how the brain builds up a picture of what's going on around you from data coming in from your sensory organs, and that it's always working to fill in the gaps. When there's insufficient information coming in, it does a lot more of the filling in of gaps and this leads to hallucinations. Dreaming, apparently, is caused by this. (The sensory organs have shut down so you can sleep, but your brain carries on filling in the gaps.)

If you're writing about a traumatised kid, I think you need to research PTSD in children, including in relation to the age of the child and the age they were when the trauma happened. There are a lot of myths about trauma and how it affects people, and perpetuating myths does harm to real people who have suffered trauma due to people believing incorrect (often negative) things about them. Even in a non-contemporary setting where PTSD isn't called PTSD and people's interpretations of what's going on are way off, what the child's actually going through needs to be accurate.

If you want a scenario where a child likes to pretend they are fighting with monsters and occasionally gets carried away and starts to see monsters, then you don't need trauma to explain this. Children who are very imaginative can scare themselves with their own imagination. I did this as a child and one of my daughters does this a lot. In low lighting, it's more likely that your brain will fill in the gaps incorrectly and make you see stuff that's not there. Listening to ghost stories and similar will prime your brain into interpreting stimuli as ghosts (rather than, say, cats and mice like my brain seems to want to do). So if your child who likes to pretend to fight with monsters is with the other kids in the dark and one of the other kids is telling a scary story about monsters, then they may all end up "seeing" a monster and terrifying themselves, and the kid with the big imagination would probably see the monster(s) first - or may be the one that's telling the stories in the first place. The imaginative kid may carry on seeing monsters for a while, especially in low light.

Another thing that also plays into this is the effect whereby our brains are primed to see faces - random patterns can look like faces (like the face on Mars and similar). Combine this with the above - hallucinations involving monsters, aliens, ghosts etc often involve seeing a face. Even when you know what's going on and you know it's not really a monster/alien/ghost, it is still extremely creepy when it happens, as millions of years of evolution has primed us to respond with fear to anything that looks like a predator, especially eyes staring right at you or faces that don't look quite right.