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Hering Illusion

The yellow lines are as straight as our monitors can make them. Yet they appear to be bulging outward, away from the center.

New research by 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 burst pattern in the background convinces our brains that we are moving forward; 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 forward movements, the red bars should begin bulging outward, growing larger as they sweep forward, and outward 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 Hering illusion is an illusory construct created by the brain; this is what your brain insists that the bars should look like one 10th of a second into the future.


Art:  R. Ausbourne

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