The mind can really play tricks with what the eye sees. This short video is a great example of a really cool optical illusion.

Update: Reader Rocco points out the Grand Illusions Web site, where you can download a PDF file that contains the pattern to cut out and fold. along with instructions. Very cool! Print it on your color printer and amaze the kids!

The site has a number of other cool optical illusions worth checking out, as well.

Know of any others? Drop a line!

(via Digg)