Aphantasia

Aphantasia is the condition of a person who is blind in their mind's eye.

They cannot "see" a picture in their head when prompted to imagine something. I, for example, am entirely able to "see" when I try to imagine anything even vaguely, even in my dreams.

It appears that everyone is on a spectrum between complete aphantasia and a very vivid detailed imagination. It must be amazing to be able to "see" without seeing.