Dawn Griffith, age 12, of Powder Springs, Ga., for her question:

WHAT IS AN OPTICAL ILLUSION?

An optical illusion occurs when we see something that is not actually as it appears to be.

We are seeing an optical illusion when we look down a long, straight road. To our eyes, it seems that the road is growing narrower in the distance. Trees and telegraph poles on the side of the road seem to grow smaller as they stretch away toward the horizon. The optical illusion makes the distant section of road seem narrower than it really is. Optical illusions make a person wearing a suit with up and down

,stripes look thinner than he would if the stripes went crosswise. Also, a house painted white looks larger than one painted a dark color.

Optical illusions of the type just described can really be called normal illusions because every person with normal eyesight experiences them.