Optical Illusions

What Causes Optical Illusions?

Optical illusions are how the eye sees the illusion. Most people now believe that seeing optical illusions has to do with perspective, or the way you look at something. The concept of optical illusion was first used by the Greeks. They built their temples so that the roof was slanted. This gave the illusion that the temple was actually standing straight.

We get used to how things are supposed to be, and sometimes our brain gets the wrong message. Our brain puts images together because it has learned to expect things, and sometimes the information might be misinterpreted. We may see an illusion because we know what we are supposed to see, even though part of a picture or design may not be completely there.

Much of our normal visual perception is deceptive in some sense. Further-away objects appear smaller than nearer objects. Mirrors show things where they can't be. The fish in ponds appear higher in the water than they really are. The rising or setting sun looks redder than it really is. Parallel lines appear to converge to the horizon. These are a few examples of optical illusions.

An everyday modern example of optical illusion is the television. The television shows you a lot of still pictures, one after the other at a fast speed. Your eyes and your brain fill in all of the missing pieces. Your brain has learned to expect movement. As a result, your brain can fill in all of the empty spots and the television appears to be actually moving to you, even though it really isn't!

A computer monitor is also one big optical illusion. If you look at a computer screen really close for a minute or two you will notice that your computer screen is made up of tiny red, green, and blue dots. The illusion is that you see more than just red, green, and blue dots; you see thousands of different colors. Our brains put the red, green, and blue dots together to make the colors.

After these early references to optical illusions, centuries passed before someone developed an interest in the subject of optical illusions again. In 1826, a psychologist named Johannes Mueller wrote two books about visual illusions. But, few people knew what he was talking about because he was the first person to call distortions, visual illusions.

Let us understand how the eye functions to enable us to see these images. There are many parts to the eye that allow it to function properly. The outer part of the eye is the cornea, a transparent covering in front of the eyeball. Behind the cornea is a lens. Light passes through the lens focusing it to form an image on the retina. The colored part of the eye is called the iris. The iris opens and closes depending on the amount of light coming into it. The black in the center of the iris is called the pupil. Light enters