Fading Dot

1. Cut the blue paper to make a 1 inch (2.5-cm) dot.
2. Place the dot in the center of the pink paper (you may want to stick it on with a dab of glue or piece of tape).
3. Lay a sheet of waxed paper on top.

Look through the waxed paper at the colored papers below. Lift the waxed paper up, away from the pink paper and toward your face, until you see very faint blue color in a field of pale pink.

Stare at a point next to the fuzzy dot for a while without moving your eyes or your head. The blue will gradually fade into the field of pink. As soon as you move your head or eyes, notice that the dot reappears. Experiment with other color combinations.

Even though you’re not aware of it, your eyes are always making tiny jittering movements. Each time your eyes move, they receive new information and send it to your brain. You need this constant new information to see images.

Your eyes also jitter around when you look at this blue dot. But because the edge of the dot looks fuzzy (as seen through the waxed paper), the color changes are so gradual that your eyes can’t tell the difference between one point on the dot and a point right next to it. Your eyes receive no new information, and the image seems to fade away. If the dot had a distinct border, your eyes would immediately detect the change when they jittered, and you would continue to see the dot.

You may have noticed that, although the dot fades, just about everything else in your field of vision remains clear. That’s because everything else you see has distinct edges.

Low contrast can affect your vision in a number of unexpected ways. In 2003, an article in the Proceedings of the International Joint Conference on Neural Networks reported that moving cars seem to slow down in foggy conditions because low contrast reduces perceived speed!