Close your eyes and picture a beach. For most people, you can “see” it in your mind—water, sand, sunshine. For around 3 to 4% of the population, however, no image appears. The mental screen stays blank, and many of them spent years assuming everyone else was speaking metaphorically when they said, “picture this.” That condition is called aphantasia, and what’s really weird: a lot of people who have it still dream in full color.