In Scott Alexander's Lot's of People Going Around with Mild Hallucinations All the Time, he shows that several people not currently on LSD still experience mild hallucinations commonly associated with currently taking LSD.
I would like to test to see if I could teach you how to see these mild hallucinations, regardless of experience with psychedelics. Below are 3 tests that should take 1-2 minutes to complete. If you choose to complete 1 or more of these, please comment both failed and successful attempts. Please also comment if you can already see some of these, even if you think it seems obvious.
Test 1: Visual Snow
Description: See the Visual Snow Wiki for a nice visualization on the top-right. I would describe it as "jumpy spiderwebs made out of light", similar in feel to the "black stars" people see when feeling faint (when they get up too quick).
I would say it's NOT the same experience as mental imagination or eye floaters.
[Edit: Honestly I mixed up different phenomena for "visual snow" in my description. Here's the update:
1. Visual Snow - Like a million very tiny dots. Very much like static/white noise in the wiki. More visible in low light conditions or when you're tired. I saw it for the first time this (8/12) morning in low-light conditions.
2. Patterned lines (?) - Like the geometric/kaleidoscopic shape in this picture. Doesn't have to be that consistent or patterned but is better described by "lines" than either of the other two. This is what I meant by "jumpy spiderwebs made out of light" and what I thought visual snow was.
3. Blue-sky Sprites - The picture is a nice animation (can be seen without looking at the blue sky but apparently it's more prominent in that case). Dots and wisps the size of a mm or a little bigger. Maybe 5-100 at a time vs the million in "visual snow". Resembles afterimages and the "black stars" when feeling faint.
4. (Also very possible there's more that I've missed)
]
Test: For 1 minute (click here for a 1 minute timer), close your eyes and try to see the back of your eyelids using your peripheral vision. If a minute elapses with nothing resembling "visual snow", then it's a failure.
If it's a success, then try to see visual snow with your eyes open, again for 1 minute at most.
Test 2: Afterimage Around Objects
Description: It's similar in feel to the image on the right in the afterimage wiki. Similar to seeing a bright light and still seeing it in your vision after you look away.
Test: For 2 minutes max (click here for a 2 minute timer), find a brightly colored object that's against a different flat colored background (a red towel hanging in front of a light tan wall, your face in the mirror in front of a white door, etc), and just stare at the object using your peripheral vision. Don't shift your eyes, just pick a spot and focus on your peripheral vision. If you don't see a colored afterimage of the object around parts of that object, then it's a failure.
Test 3: Breathing Walls
Description: It looks like the static surface you're looking at (floors, walls, ceilings) is shifting, rotating, swirling, "breathing" (sort of dilating back and forth?) even though you know that it's actually still static. Usually more apparent in patterned surfaces than plain colored ones.
Test: For 1 minute, find a larger, textured surface (carpet, pop-corn ceilings, [other examples?]), and stare at it using your peripheral vision. If after a minute of staring you don't see any moving, shifting, etc, then it's a failure.
Well my point was that the experience isn't that your vision is replaced by another sensation. In the linked slatestarcodex there is a comparison picture. That kind of thing might suggest that the visual snow would appear the same as if there were mist or something. But it in fact superimposes or some relation which would only make sense in perceptual analysis. Like if you repeat the same word multiple times it can fail to seem like a word. But you are still aware of the all the phonemes/letters of the word. It would be weird if somebody could hear the word but could not hear the individual letters. And hearing the letters doesn't interfere with hearing the word. Saying that hearing single letters would be "hallucinating things that are not there" would be really backwards. So in vision when I can see the rawer visual data I am not seeing stuff that isn't there.
If you have a correctly working monitor and take it appart and study it's function it will stay as a functional monitor. If you wire it differntly then it might function differently but if you refrain from rewiring it stays correctly working. If you look inside and see how your visual cortex works you might change your opinion on your visual cortex but it is unlikely that it started to act up just because you looked into it (in the cognitive sense). On the opposite pole if you intentionally set out to imagine a picture of a apple if your visual cortex complies and provides a red apple picture that would be a hallucination. But if it shares what it already has anyway there is no fraudulent component. If it happens during normal operation it is not an artifact even if you were not aware of it's existence. There is some good quote that has parts to the effect of "People can handle the truth for they are already enduring it "