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Eye And Brain
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 the eye through the pupil. When you look at an object, light reflects off it and enters your eye through the pupil. The lens focuses that light into an image, or a small picture of the object, on your retina. The funny thing is the image is upside down. Inside the retina are millions of nerve cells that send the image along the optic nerve to the brain. It is really because of the brain that we see.
The Brain Seeing doesn’t actually take place in the eyes, but in the brain. The brain puts together the nerve impulses from the optic nerve, flipping the image right-side up, and allows us to see. Scientists still do not fully understand how the brain does this. They do know that damage to certain parts of the brain can cause sight problems and that we all have an area of the eye called a blind spot. This blind spot is located where the optic nerve enters the retina. We do not usually know we have the blind spot because our eyes move around giving us enough information to see properly. However, sometimes this blind spot can cause your brain to put together the impulses wrong, causing a misperception about what you are seeing. So just as the eye and brain work together for us to see properly, they also work together for us to see illusions.
Why We See Optical Illusions
We do not know for sure why we see optical illusions, but there are some popular explanations. Some people think we see illusions because of the physical traits of the eye. Others think it is because of culture. In science, when theories are made to help explain things they are usually believed until new evidence comes up that the theory cannot explain. That may be the case with optical illusions.Most people now believe that seeing optical illusions has to do with perspective, or the way you look at something. Scientists who are trying to answer the question of why we see optical illusions have discovered that not everyone sees them in the same way. Even if all your friends see the same image, people around the world may not.Scientists tried illusions out on some people in the African country of Uganda. The Ugandans who lived in the cities and had seen drawings and photographs were fooled by the illusions. However, those Ugandans who lived in the villages away from big cities and hadn’t seen drawings or photographs were not fooled at all. This evidence shows scientists that not only do the eye and the brain work together to make us see optical illusions, but past experience plays a part too.Therefore, the latest theory about why we see optical illusions is that the eye sees them, but your brain uses your past experiences to interpret what the eyes see.
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