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Which white horizontal line appears to be the longest and which appears to be the shortest? Did you think that the upper white line is bigger than the lower one? Please take this time and measure both lines, perhaps you may be flabbergasted by the results. By this time, you had just witnessed a concept that may upset ones previously held presumption about the nature of reality.
The illustration that you had examined is an optical illusion called the Ponzo illusion. The Ponzo illusion was first discovered and described in 1913, by an Italian psychologist, Mario Ponzo. The parallel white lines in the picture was seem as if they were different sizes. If you did measure them, you would have noticed that they're actually the same length. Why does the lines appear to be “bigger” as they appear to be further? Can you see how the vertical lines tend to gather onto a generic point in the distance? The vertical lines starts to become smaller and the road shifts inward towards the upper line, making the size seem larger than the bottom line. The cars, on the right hand side of the picture, are considered “small” in this picture due to the distance away from the camera, which made it a binary effect on size of the white lines.
Why does this phenomenon occur? Well, Ponzo believed that the human brain judges the objects size according to its background, and to prove his ideas he drew two identical line’s across a pair of converging lines. When our eyes first see the Ponzo illusion the two identical lines look different in perception, but when measured, they are the same size. The converging lines seem to move towards horizon or the vanishing point so in our mind we see them getting smaller because the further the object gets the smaller it becomes in our mind, but the line that is drawn over the vanishing point is the same size as the original line but with the background being farther and smaller the line looks bigger. The Ponzo illusion is mostly illustrated on railway tracks for better understanding.
Cherry, Kendra(2010) Ponzo Illusion. Retrieved October 6, 2010 from the World Wide Web: http://psychology.about.com/od/sensationandperception/ig/Optical-Illusions/The-Ponzo-Illusion.htm
Cool Optical Illusions(2007) Image. Retrieved October 4, 2010 from the World Wide Web: http://www.coolopticalillusions.com/crazy/lesson_in_perspective.htm
New World Encyclopedia: Ponzo illusion page (2009) Gathered info on October 5, 2010 from World Wide Web: http://www.newworldencyclopedia.org/entry/Perception