Instructions: Stare at the black spot in the center of the four colored squares for about 30 seconds. Then scroll down and move your gaze to the black spot in the uniform white area. Note the colors of the afterimages relative to the colors of the original stimuli. Did they appear different?

Try to count the number of black dots on the image below...

Stare at the four black dots in the center of the image for 30 - 60 seconds.
Then quickly look at a  single color wall near you. You should see a white circle with an image inside it.