Diana Ng 9.35 Project Spring 2001 Stare at the bluish dot for awhile without moving your eyes or your head. The dot will gradually fade into the field of green.
Some people find that the dot fades more rapidly if they stare blankly at the edge of the square.
As soon as you move your head or eyes, notice that the blue reappears. Although we are not aware of it, our eyes are always making small and rapid jittery movements. Each time your eye moves it receives new information and sends it to your brain. You need this constant new information to see images. The shows the effect of fatigue on your visual system.