http://ccl.northwestern.edu/netlogo/...0Illusions.png
are they straight?
http://www.d.umn.edu/cla/faculty/tro...ircles.700.gif
are they spinning?
http://sprintfun.com/marginally/wp-c..._illusions.jpg
are they moving?
http://www.free-jokes-online.com/thu..._Illusions.jpg
what do you see?
post any other illusions you can find