It’s funny, really, because aphantasia is supposed to be fairly rare, but every time a thread like this comes up, folks come out of the woodwork saying “Oh, yeah, that’s me.” Makes me wonder if it isn’t a lot more common than believed, but people just don’t realize they have it. There don’t seem to have been any real studies done on it.
I can have conversations in my mind, but there’s no visuals associated with it. It’s like a radio broadcast vs. a TV program. I can think about the description of an object, and recite back its physical qualities, but I can’t visualize that object at all.