Believe it or not, the horizontal lines are all perfectly parallel. To prove this to yourself, just squint at the image or look at it from the side. Notice that, even after you’re completely convinced that the lines are parallel, the illusion continues to work....

This one’s a variation on the Munker Illusion, created by David Novick. The circles in the image are all the same color. The only thing that differs is the color of the lines around them. The illusion is a vivid demonstration of the fact that we don’t directly...