It's zero trust networking for your brain, and you're asking "but how do you decide which ip addresses are safe?". That's the neat part, you don't.
Nothing is real. Not for me or for you. That is my greatest insight of my illness.
You all have very narrow band schizophrenia, mine is just more, uhm, loose.
So if I feel like some shadow agency is tracking me I just say; "So what.", If I think what I picked up from the supermarket I just say; "So what if I die." I really had to stop caring about dying or suffering.
The only time I know when I am alone in my perceptions is when I ask someone. For example, I was sitting in a restaurant and I these four Mexican workers were turned around staring at me. I asked my friend if they were and she said no. Now I do not know if I am able to pick up on something, maybe I could somehow tell they were talking about me adn my brain made me aware by making it look like they were looking at me. But again, so what is my answer.
The day before that I felt my dead great uncle was telling me to go to Dillon, MT to make amends for him getting arrested there in 1954. So it was a tough week for me.
I've seen that too. It's as if the brain's "saliency threshold" is set too low - suddenly, there are no coincidences; everything is relevant and connected and has personal significance. There's no clear dividing lines between logic and intuition and madness; many of the people we perceive as smartest or most creative are somewhere in the middle.
All people have neurotic moments (That someone is looking at them, or believe in some mild conspiracy or whatever). The people who say they aren’t are lying or good at hiding it.
Someone close to me and typically pretty rational has one where she thought bugs were in her bed after repeatedly bug bombing the house. Half the State of New Jersey think we are in the midst of a drone invasion. Thank god we invented the scientific method and other tools for reasoning that can compensate for our flawed perceptions.
100% normal people do not get involuntarily committed to a psych ward. (Well, sometimes they do, but that is another story) The disorder comes when it disrupts your daily life. The thing you mentioned do not do that. Mine did.