Senses are a weird topic for me.
What I see literally? Colours that form the most interesting geometrical forms and shapes that resemble all kinds of things, even such as animals. When I concentrate on what I see, the shapes and patterns shift constantly and I see lots of different things there. Numbers, real stuff like chess pieces...
I can visualise anything with my eyes open. However, visualising with my eyes closed is problematic because of the constant movement of the shapes I'm forced to see I usually don't close my eyes when I go to bed, because it's more dark with my eyes open - but when I manage to relax and concentrate, then I happen to see full blown photographic pictures. With real colours, shades and just as if it were me looking at a static scenery.
The photographic pictures I see are in my head, definitely, yet I 'see' them as if I were an observe standing in that scenery. It's like my vision fades, because when I abruptly open my eyes, the photograph lingers for a moment, I see nothing else of my real surroundings for the smallest moment and then normal vision returns. Having no idea, I imagine that's how blindness can be - loss of vision, not blackness, but just nothing.
I hate closing my eyes, it's scary. Funny thing is, when I was small, I'd resist to open my eyes. I ran around with my eyes closed, yet I didn't bump into anything and knew were to turn and stop. I was extremely overwhelmed by sensory input back then, I'd feel things without touching because of the temperature they gave off.
Shutting one of my senses today freaks me out. I need a certain amount of input to keep my senses working normally, otherwise they start firing freak signals on their own.