Visual illusions fascinate people because they demonstrate how our visual system can be “tricked” into seeing inaccurately. We already discussed many illusions in class during our lectures. We have talked about Mach bands, in which small changes in lightness are seen near a border even though no changes are present in the physical pattern of light; simultaneous contrast and White’s illusion, which two physically identical fields can appear different; and the Hermann grid, in which small gray spots are seen that aren’t there in the light. Visual illusions can also be seen with sizes. This visual illusion comes with the perception of size and the perception of depth. A good example of this illusion is provided by the Muller-Lyer illusion.