

Best Visual Illusion of the Year: The break of the curveball - trs90
http://illusioncontest.neuralcorrelate.com/2009/the-break-of-the-curveball/

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GraffitiTim
Neat. I don't think anything will ever beat Checkershadow though:
[http://web.mit.edu/persci/people/adelson/checkershadow_illus...](http://web.mit.edu/persci/people/adelson/checkershadow_illusion.html)

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arketyp
Spinning objects (balls) must certainly be of biased occurrence in modern
times of human civilization. Assuming the illusion is a cognitive artifact of
a learned phenomena, I wonder how a caveman would recognize this
demonstration. Would the illusion be lost? Probably the experience would be
quite rad, some way or another, however.

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antiismist
I'd guess that it is not an artifact of learned phenomena. The rotation has
the pixels of the ball moving from right to left, and the illusion is that the
ball is moving right to left.

I think that this would hold up for cavemen - that if they see part of an
object moving from right to left (in their peripheral vision) that they'd also
see the whole object moving from right to left.

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lutorm
I agree, I think it has to do with the motion filtering of your retina. If the
rotational speed is faster than the linear movement, the motion detection
circuits on your retina will detect movement predominantly in the rotation
direction. On the other hand, when you fixate on the ball, the brain instead
judges motion by eyeball movement, and the illusion disappears.

Very cool.

