I’ve always thought this was really hard to describe. I think I’m a 1. The idea of fully picturing something is such a natural thing, but I also don’t know what level of vivid people actually mean.
When I picture the apple, I could easily write a detailed paragraph about what it looks like. I could even easily picture an environment for it that just sort of comes into frame (always on an apple orchard, during the afternoon).
I can easily even put myself in that space mentally.
I’ve just never thought about this being something other people can’t naturally and quickly do that when I saw this question, I assumed people were describing actually fully fooling their senses into the thing physically appearing before them.
I picture it like another monitor or render layer that I can flip to, manipulate, and test in to work out concepts.