Weird Wonder

What Happens If You Stare at One Color for a Long Time?

 

Materials

• pencil
• ruler
• 2 sheets of white paper
• yellow, green, and black marking pens
• timer

Try This

1. Draw a 6-in. (15-cm) square on one sheet of paper.
2. Draw a 1-in. (2.5-cm) yellow border around the square.
3. Color the area within the border green.
4. Put a black dot in the center of the square.
5. In bright light, hold up the paper and stare at the black dot for about one minute without blinking.
6. When time is up, look at the blank sheet of paper. What do you see?

What's Going On?

You saw an image of the square on the blank sheet of paper, but in different colors. Special parts of your eyes, called cones, distinguish among green, red, and blue light. These are the three primary colors that make up white light. When you stared at the black dot for a minute, the cones corresponding to that color worked continuously. When you later stared at the blank white paper, which is made up of three colors, only the cones that were not working earlier worked, because the others had been overworked.