The Hallway Illusion
What to see and do: The man in the back seems bigger, but actually they are the same size. You can move either man on top of each other to see that they are the same size.
What's happening: The wall looks smaller towards the background. That makes the man on the right look bigger than the wall but the other man looks smaller than the wall.
Credit: This illusion was based on an illustration by Stanford psychologist Roger Shepard.