I'm really curious about this because I recently realized I can't picture anything in my head, ever. Can't see a simple object like a purple ball, I just think "It is a ball, and it is purple", but no image, I didn't even realize it was a thing.

To me, anything refering to "seeing in your mind" was a metaphor, "counting sheeps" was just counting any random word in a boring rhytim, I can't picture a person face to save my life. Not even people I see everyday, my family or even the woman I love for 10 years, it can get lonely, but to me that was normal so my mind tried to make it up with strong narratives about them.

I was always used to read, and I never felt I was "understanding less" of any book, but discussing with anyone was something very dificult, it would be like talking with some random chinese guy who thinks the word in english for "potato" is "tomato" , you could really make an effort to understand but if he only repeats he ate "fried tomatos" last night with a disgusted look in his face, you may never understand him. It can be like you both are talking about complete diferent things.

Funny part is I have an amazing memory, probably compensating for the lack of images in another way.