AphantasiaDan Fitch sent me a fascinating e-mail last week:
Side note for your Friday Links... you just posted about being able to visualize a solution in your head. Did you know there are people out there who have "aphantasia", which means they simply do not have a mental "inner eye" of any kind? It's sometimes called "mental blindness." A good friend of mine discovered last year that he had this. He assumed that everyone else was just being metaphorical when they said "picture in your minds eye". Some people are better than others at powering their "inner eye"; mine is pretty weak, my sister is super strong, and some have none at all.
The strangest part is, this was only recently discovered, even though as many as 1% of the population may have aphantasia. My friend who is mentally blind is writing a book. And when I read it, or talk to him, I certainly cannot tell that he is different as far as imagining things. But his inner life must be significantly different than mine! WEIRD.
Here's a BBC article about it from last year: Aphantasia: A life without mental images.
I am lucky, because even though I have a hard time visualizing spatial relationships in 3-D, I do have incredibly vivid images at times. I had no idea that for some people, this just didn't exist.