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Squashed Square Illusion

The rings in the background are accurate, concentric circles and the red square is really square with straight sides.  Right now though, the square looks like it is bent inwards; sort of caved in.

Dr. Changizi at Rensselaer Polytechnic Institute describes this illusion in terms of the brain's ability to project our world view into the future (The Vision Revolution, 2009).  The ring pattern in the background convinces our brains that we are moving backwards; not the whole body, just the part of the brain that helps us see.  If this is so, the mind ponders, then as in similar backwards movements, the red bars should begin distorting inwardly, growing smaller as they recede towards the center in our field-of-view.  So the brain shows us the above results.  What!!!??  How can the brain anticipate a distortion illusion?


There is a one 10th of a second delay between the instant we "see" something and when we perceive that something; call it brain processing time.  It may not sound like much but it can be critical if you're watching a tennis match or swinging at a pitched ball at more than 90 miles an hour.  To compensate for this necessary processing delay the brain has evolved the ability to project our world view one 10th of a second into the future. In this way we always see in the present.  What you are seeing in the Squashed Square illusion is an illusory construct created by the brain; this is what your brain insists that the square should look like one 10th of a second into the future.

Art: Copyright 2003 R. Ausbourne


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