A while back I discovered that I have aphantasia. I can construct elaborate ideas that are wholly visual in my head and describe them to other people in great detail but I cannot visualize an ounce of it in my own head. I've since read accounts of illustrators and graphic artists who are successful in their fields and who draw for a living and yet they also have aphantasia. I think this internal monologue thing probably isn't terribly different. FWIW, I _do_ have a _very strong_ internal monologue.