Home History How We See Perception Types Use Activities Glossary Bibliography   Impossible Optical Illusions 3 Dimensional Illusions Camouflage And Optical Illusion Facial Illusions After Images Ambiguous Optical Illusions Distortion Illusions Colour And Shadow Illusions VIEW SOME OF MY BLOGS Runescape Car Crash Clips Crops & Commodities Games Online Periodic Table Funny Signs           How we see Optical illusion   When a person looks at an object of a particular colour for a long time and then suddenly looks at a blank space, the person sees a ghostly outline of the object in its complimentary colour. If the object is red, the person sees green. If the object is blue, the person sees yellow. This happens because the cones are sensitive in pairs. When a cone sensitive to one colour is turned off, the other colour is briefly turned on. How we see optical illusions, that involving in our two most distinctive body parts: eyes and the brain, how they interactive with which other and then the eyes can play tricks and fool us. So let learn our eyes and brain as below: The Eye When light enters the eyes, it passes first through the cornea, a transparent cover, and then through a watery fluid called the aqueous humour, and through the pupil, which is an opening in the coloured part of the eye called the iris. The size of the pupil increases when there is less light and decreases when there is more. Light next passes through the lens, which focuses the light through a transparent jell, called the vitreous body, onto the retina. The retina has two types of light sensitive cells, rods and cones. Rods are particularly sensitive to shades of light and outlines, and they are important in both night and peripheral vision. Cones have specialized pigments that are sensitive to either red, green, or blue. Cones enable people to see details. Rods and cones cover the entire retina except for a small area just above the optic nerve, known as the blind spot. 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 Nobody know why we see optical illusions, but there are some few 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. Until now, 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. < previous page   Home│ History│ How We See│ Perception│ Types│ Use│ Activities│ Glossary│ Bibliography│ Term│ Top Designed by Darwin Peczek Erskine Park High School