This one really starts to mess with your mind after awhile. In this optical illusion picture, each box has a gradient that is going from dark to light in one direction or the other. Although the vertical lines are absolutely straight, each box will start to distort and look more like a trapezoid pointing up or down, depending on which column you look at. The boxes with the dark gradient on the top and the light gradient on the bottom appear as trapezoids that have a smaller top, and a larger base, even though they are all perfectly straight. Whereas the boxes with the light gradient at the top and the dark gradient at the bottom appear to have a larger top and a smaller base?
Don’t stay on this page too long unless you want a headache!
Another amazing part of this illusion: It’s a principle that is often used in magic tricks by magicians to cover something, and that is, that things that are white appear larger than things that are dark. If a magician wants to conceal a large area (or an architect wants to conceal a large unsightly object, painting it as black will make it sink into the background much more!).