What is An Optical Illusion?
An optical illusion, or visual illusion, refers to a state wherein visually perceived images differ from the real object. While some people may find this frustrating, others continue to look for and enjoy them. It may also be described as a mismatch between the immediate visual impression and the actual properties of the object. In the case of optical illusions, the brain processes the information gathered by the eye and gives a perception that does not tally with the actual object.
Many of us believe we are in control of what our mind perceives but an optical illusion can make you see things that are not actually there – an object that seems to be moving might be standing still or the lines that appear curved might actually be straight, however do not think it your eyes’ fault, it just means that you don’t always see what you think you do.
This happens because of the way an image is perceived and interpreted by the brain, so the perception of an illusion has more to do with the brain and not so much to do with optics of the eyes. The brain needs to interpret everything that enters the senses and at times these interpretations may be wrong. There are three broad types of optical illusions: Literal optical illusions that differ from the objects that make them, physiological illusions that occur due to the effect of excessive stimulation of a specific type on the eyes and the brain, and third, the cognitive illusion, which is a result of unconscious inferences.
Optical illusions can be fun, and at the same time it tells us a lot about how the brain and perceptual function work.
Some examples of interesting optical illusions:
• The Hermann Grid illusion: The Herman Grid is a great example of the fact that sometimes we see things that are not really there and overlook things actually present. Looking at the Hermann Grid closely it can be noticed how dots at the center of each intersection seem to shift between white and gray.
• The Ponzo Illusion: Objects seem to be closer together as they become further away when one looks into the distance. For instance, in the Ponzo Illuson, the outside border of the road or railroad appear to converge as they recede into the distance. Place two lines over an illustration of a railroad track and try to figure out which line is longer, the line that shows distance will appear to be shorter, but in reality both lines are similar in length.
• The Zollner Illusion: The Zollner Illusion demonstrates that the way your brain interprets the image can be affected by the background. This is a unique illusion that can make a viewer feel slightly queasy if they keep staring at the image. The background seems to interfere and our brains find it difficult to interpret the image correctly.
• The Kanizsa Triangle Illusion: The Gestalt law of closure indicates that we tend to see objects as a related group if they are close together. In the case of the Kanizsa Triangle, we tend to ignore the gaps and see contour lines that do not exist in order to form a cohesive image.
Japanese mathematics professor Kokichi Sugihara spends much of his time in a world where up is down and three dimensions are really only two. Professor Sugihara is one of the world’s leading exponents of optical illusion, a mathematical art-form that he says could have application in the real world.