Optical Illusions Stem from Ability to See Future

Optical illusions are one of the more amusing parts of science. The amazement that stems from seeing something that isn’t so never ceases. Optical illusions, when the eye sees what isn’t there, are distinct from political delusion, which is when ideology and reality don’t match, and the individual opts to believe the ideology. Now, Assistant Professor of Cognitive Science at Rensselaer Polytechnic Institute Mark Changizi says he’s figured out why optical illusions happen. He explains, “Illusions occur when our brains attempt to perceive the future, and those perceptions don’t match reality.”

He points to the “Herring Illusion,” which resembles bike spokes around a central point, with vertical lines on either side of this so-called vanishing point. Professor Changizi says, “Evolution has seen to it that geometric drawings like this elicit in us premonitions of the near future. The converging lines toward a vanishing point (the spokes) are cues that trick our brains into thinking we are moving forward — as we would in the real world, where the door frame (a pair of vertical lines) seems to bow out as we move through it — and we try to perceive what that world will look like in the next instant.”

It may be more accurate to describe optical illusions as misperceptions. Professor Changizi noted in an interview with Scientific American, “There are four different domains of misperception: The first is illusions of size. The second is illusions of speed. The third is luminance, or contrast. The last is illusions of perceived distance. Now, there are different ways of affecting those kinds of misperceptions—the key features that are causing those illusions. For example, size differences within your visual field could cause misperceptions or illusions of speed.”

What possible evolutionary advantage is there to this? Science Daily explained, “It takes our brain nearly one-tenth of a second to translate the light that hits our retina into a visual perception of the world around us. While a neural delay of that magnitude may seem minuscule, imagine trying to catch a ball or wade through a store full of people while always perceiving the very recent (one-tenth of a second prior) past. A ball passing within one meter of you and traveling at one meter per second in reality would be roughly six degrees displaced from where you perceive it, and even the slowest forward-moving person can travel at least ten centimeters in a tenth of a second.” Catching a ball isn’t a matter of life and death (despite what some baseball fans might believe), but in a primitive environment, it’s clearly a survival-prone characteristic.

This discovery has implications for the arts. In his book, This is Your Brain on Music, neuroscientist Daniel Levitin explains that music interests humans because of the anticipation of notes within a culturally familiar context and the resolution of that anticipation that comes from hearing the notes. Human ears like little surprises. If Professor Changizi is right, the same may apply to visual arts, offering artists a better understanding of why a film, play or dance works or doesn’t.

© Copyright 2008 by The Kensington Review, Jeff Myhre, PhD, Editor. No part of this publication may be reproduced without written consent. Produced using Fedora Linux.

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