Back when I was on some medication to help me sleep, it came with the side effect of having vivid dreams... and if I didn't fall asleep fast enough after taking it, I'd get hallucinations while my eyes were closed. I knew I wasn't seeing what I thought I was seeing, but I wasn't really in control of the imagery. In one case, I thought there was a suit of armor standing over me and mumbling. In another, I was laying in bed, but I was seeing the living room from a few feet outside of my bedroom.
My - and what I presume is "normal" - mental imagery isn't any different than those hallucinations, with the exception of I am willing what I imagine, and therefore control what I "see" in my mind. The colors, contours, lighting, shading, and so on are all like what you would see with your eyes, though the actual level of detail is less.
My - and what I presume is "normal" - mental imagery isn't any different than those hallucinations, with the exception of I am willing what I imagine, and therefore control what I "see" in my mind. The colors, contours, lighting, shading, and so on are all like what you would see with your eyes, though the actual level of detail is less.