Learn

Here are more vision tricks, this time using colored paper to help learn more about light sensitive cells without which we would not be able to recognize color.

• 4 white posterboards or large pieces of paper
• Bright green, red and blue construction paper
• Small piece of black construction paper (a black marker will do)
• Scissors
• Glue or glue stick

1. From each of the pieces of colored paper, cut out a simple shape– like a bird.
2. Next, glue each shape on its own white posterboard or white paper, leaving one white board/paper blank.
3. Cut out a small black eye for each bird (or else draw it on there with black pen)
4. On the blank board/paper, draw a big birdcage.
5. Now put the completed posterboards, or papers, in a well-lit area. The better the lighting, the better this experiment will work.
6. Stare at the eye of the red bird for 15-20 seconds, and then quickly stare at the birdcage. What color is the image that you see?
7. Now, repeat the process staring at the green bird. Finally, stare at the blue bird. What color is the image that your eyes see in the cage now?

What Happened:

The birds that appear in your cage after you have stared at the bird cut-outs are called afterimages. An afterimage is an image that stays with you even after you have stopped looking at that object.

Your eye is lined with light-sensitive cells called rods and cones. Cones are sensitive to colored light, and there are three different types of cones that react to different colors. When you stare at one color of bird, the cones that respond to that particular color become fatigued. When you look at the white board with the black cage, the other color cones compensate, and you see combinations of the two other color cones.