Some interesting optical illusions
Posted by: blitzer
Date: 2008-10-30 17:56:14
Two congruent circles are surrounded by other circles, one of them surrounded by large congruent circles, and the other surrounded by small congruent circles. The one sưrounded by small circles seems to be bigger.
http://en.wikipedia.org/wiki/Lilac_chaser
Stare at the black + for 20-30 seconds.
http://en.wikipedia.org/wiki/Caf%C3%A9_wall_illusion
Parallel lines appear to be bent.
http://en.wikipedia.org/wiki/Image:Revolving_circles.svg
Move your head back and forth.
http://en.wikipedia.org/wiki/Missing_square_puzzle
Four objects are formed to make a 13 by 5 right triangle. When rearranged, they seem to form a triangle with the same proportions, except with 1 missing square.
http://en.wikipedia.org/wiki/Fraser_spiral_illusion
A spiral? Not really.