Ask people to visualize a thing. Pick something like a house, dog, tree, etc. Then ask about details. Where is the dog?

I have aphantasia and my dog isn't anywhere. It's just a dog, you didn't ask me to visualize anything else.

When you ask about details, like color, tail length, eyes then I have to make them up on the spot. I can do that very quickly but I don't "see" the good boy.