Color And Shadow Illusions
Color and shadow illusions depend on the way we see and compare things like contrast, colors and the edges of things. Hermanís grid is a good example of this type of illusion. Look at the image below.
What happens? Do you see little shadows in the intersections? This is caused by light receptors in our eyes which help us to see high contrast images. You may think the receptors arenít working correctly, but they are working fine. Nearby receptors are taking snooze. In other words, the fuzzy spots are caused by lazy eyes! Sometimes these are also afterimages.