Anatomy and Physiology: Tricks Your Eyes and Brain Can Play on You

The visual virtual lab project begins with asking whether a horizontal table or vertical table is longer.  It turns out that preceptual clues make us think that the vertical table is longer, but they are actually the same size.  As a result there is a difference between reality and what our eyes perceive.

This is known as the Rubin vase illusion, made by psychologist Edgar Rubin.  Because of figure-ground segregation, we either see two faces on a white background or a vase on a gray or black background.


As the visual project continues, it discusses how our brain is sensitive to contrasts.  It gives us two circles, one light gray, and one black.  Each has a smaller gray circle in the middle.  Although both of these smaller gray circles are the same brightness, we think that the one in the larger light gray circle is lighter because of the color around it is lighter.

This is the Thatcher illusion.  When the images are upside down, it looks like both of them are smiling.  However, when they are flipped right-side up, one is smiling and the other is frowning.  This is because we draw familiarity from experience.  We process the image and fill the rest in based on experience, even though both images are not smiling.








Sources:
rubin vase illusion picture from: http://www.lifeisanillusion.info/the-rubin-vase-illusion/
thatcher illusion picture from: http://scienceblogs.com/mixingmemory/2006/09/cool_visual_illusions_the_marg.php
information from: http://virtuallabs.stanford.edu/demo/