Look at something with a lot of light, preferably sunlight. Then close your eyes and put your hand over your eyes, or close your eyes tight. Whatever you were looking at will be imprinted in your mind. I spent like an hour practicing this in class. it's pretty hard, but satisfying. it's actually really clear, too. it only lasts like 10 seconds. i'm gonna try and get really good at it, like try to interact with or manipulate the environment, etc.
one of the times, out of nowhere, i saw a room with a dark figure standing in the middle of it. it scared me so bad it was great
i don't think there's anything wrong/unusual with doing it, but i could be wrong.