[vidarh]

To me, my inner monologue is like that, and it is constant, every waking moment unless I make conscious efforts to suppress it, like while meditating.

As for mental images, I have them all the time while dreaming, but I've only experienced them once in my life while fully awake, and profoundly clearer than any dream. I can remember what some of the images in a few dreams looked like, but once I start waking up, the visuals fade within 30 seconds or so of being aware.