The simplest way to describe an optical illusion is that it is a “trick” that our eyes play on us. We seem to see that isn’t really so. Or we may be able to see the same object in two completely different ways. If our eyes are functioning properly, and they as instruments for seeing exactly what is before us, how can they play “tricks” on us?
Here is what makes it possible. Vision is not a physical process. It is not like photography, for instance, which works mechanically. Vision is really a psychological experience, because it is not the eyes that see, but the brain!
The eyes are mechanical instruments for receiving impressions. But when those images reach the brain, a judgment takes place. The cells of the brain have to decide what they think this image is.
What Helps The Brain Make That Decision?
One of the important things is the work that the eye muscles have to do in order to see a thing. In judging distances, angles, and the relationship of things in space, our eyes have to move back and forth. Our brain says that our eyes have traveled a certain distance because the brain has an idea of the amount of energy and the time it took for our eyes to move back and forth.
So now we have the possibility of one kind of optical illusion. Sup- pose there are two lines of length, but one is vertical and one is horizontal. The horizontal line will seem shorter to us because it is easier for the eyeballs to move from side to side than up and down. So the brain decides the horizontal line must be shorter!
What Are The 3 Types Of Optical Illusions?
literal illusions, physiological illusions, and cognitive illusions.