Do you see them in dreams? I normally struggle to visualize things but when I'm half asleep my imagination suddenly has color and detail that normally doesn't happen when I try to picture stuff
But dreams are ultra-visual experiences for me, to the extent where I will occasionally have flashbacks or deja vu to dream images that were exceptionally strong.
So that nullified my suspicion! That said, I do wonder if it's a spectrum, in that some people are more or less visual in their thinking, and on the extremes people may get the capability snipped, as the dim visual hum fades to black and background noise.