I think people that dont visualize much or at all get the wrong impression on the fidelity and stability of the ability to visualize.
A standard example of such visualisation is 'in bluish-white light on a dark background, imagine a line. from the same light, imagine drawing a circle using the line as a diameter. Now draw an equilateral triangle touching the boundary of the circle. Then a square around the triangle. Finally, draw another circle around the square, and hold the resulting image stable in your mind' (yes, this shape probably inspired Rowling's description of the deathly Hallows. It's a very old exercise).
I can visualise the line and the first circle easily. I can add the triangle, but at this point it already takes some effort, I can't do it if I'm even a little distracted. Typically, adding the square makes me 'lose' an earlier detail, usually the line, from my visualization.
That's probably not very informative to your question though, because visualization doesn't have the same sorts of rules around complexity a graphics screen does, the brain definitely uses some form of internal shorthand. I can picture a particular celebrity as easily as I can picture a circle, and picturing her holding an item from my grocery list in each hand is if anything somewhat easier than picturing two other elementary shapes connected to the circle. Maybe because humans are used to imagining other humans holding things, I'm not sure.
In any case, there are definitely limits to what a person can visualize, and they're pretty modest for the untrained mind, but it's quite unlike a graphics program where one could simply count the number of pixels required. Not sure if that helps or not...
I can't even visualise the dark background or the light.
But I don't "see" any of that. In any way. You tell me it's drawn in a blue light, or the square is an inch thick piece of plaid: sure. now it's plaid. I already have colors picked out and I'm remembering how the threads in the fabric produce patterns when viewed up close, especially where the stripes overlap. I'm not seeing anything though.
It's closer to how I deal with math - 5x7 is 35 because I know it is. I memorized single-digit multiplication long ago, and if I ever want to reassure myself I can just do repeated addition. It's not accompanied by literally any metaphor or mnemonic or whatever, it's just equal to thirty five, and 35 is 三十五 is ٣٥ regardless of where it comes from. Similarly, rotating the deathly hallows by 90 degrees is just a rotated deathly hallows - the line is now sideways, the triangle has a vertical edge on the left, the green stripes in the plaid are now sideways and the diagonal-hashed intersections at the overlaps are in the opposite direction, etc.
---
Maybe also oddly, I have a very good visual memory in practical terms. I disassemble and reassemble stuff with no trouble, and when I'm looking for a phrase in a book I read a year ago I can generally find it within an inch of where I remember it on a page (but not usually what page it is). When I'm looking for things I lost, I generally hunt by looking for colors or textures that were adjacent to where I last remember it. I'd never describe how I remember that or how I look for it as seeing though - there's just a wadded up blanket near it with a big fold that tangents with the far right corner of my phone, so I go looking for wadded up blankets.
I feel like this is probably mostly a sensory-qualia thing, almost totally orthogonal to what is being thought about / done. People who can see things in their mind's eye can't necessarily do anything with it beyond having the experience, and people who are totally internally blind can do things that seem to be based on sight. And to some degree both of those are train-able.
I suspect it's more like dreaming of a thing than a photograph-like construct, at least in a significant number of cases. It'd also explain why it seems so dream-like when you get into specifics, where the pieces may make sense but they do not even remotely add up to a coherent whole - context or something is lost each time it's visualized. The main important part is that it feels like seeing a thing, which is both 1) something not everyone can do/achieve, and 2) more than sufficient for individual use or broad concepts.
And it can probably be trained to be more stable and detailed, and there are rare outliers where it's significantly better - there do seem to be people capable of maintaining a stable "thing" from inception through real-world construction.
I would say that we can dream about most things but there are a few obvious limits as there are types of thoughts that will make you wake up:
* Reading is difficult and typically books in dreams don't have words in them.
* "Pushing" (there is no good word for this) the direction of a dream in a particular way too hard will wake you up. It has to be done very gently.
* Abstract reasoning / logic is difficult in dreams, it causes you to concentrate too hard and then you wake up.
In general the limits are to do with the two dominant modes of thought: spontaneous unquestioning creation of ideas is very compatible with dreaming and you can float easily between multiple "perspectives" or versions without any problem. Analytical / questioning / critical thinking is incompatible with dreaming and causes you to wake up. Lucid dreaming is typically learning how to float in the sweet spot between the two modes.
I think that I know that I dream, deep down, because of things that former roommates and my wife have told me, but... I am trusting them at their word. And I know they're not lying to me, because why would they, but... I don't know it myself because I haven't experienced it.
Lately, since I had been taking Lion’s Mane as a supplement, my visualizations and visual experience has been slowly regaining in clarity, stability, and fidelity.
