The coolest optical illusion.

[napalm]

http://www.johnsadowski.com/big_spanish_castle.html

Really bizarre. When you mouse over the picture, it shows a castle in black and white. But if you concentrate on the dot for 30 seconds, and then mouse over the picture while still looking at the dot, the entire picture will appear in full color until you move your eye.

I'm suprised how well that worked, bravo! We did a unit on the eyes and vision in a psychology course, and this was covered, but of course I already forgot what it's called. Basically what happens is when you stare at the image for long enough, you are heavily using your cones for those corresponding colors. When the image is taken away, your eyes will faintly show a different color while the cones that were used before "recharge." One picture, for example, was an american flag with a yellow border around the stars with black and white strips. Once you stared for 30 seconds you'd flip to a white paper and you could see the American Flag in all of its red white and blue beauty. I'm probably a bit off and the exact process, but it gives you the general idea of what's going on.

[Brand X]

The effect is called an after image. You see the complimentary opposite color of the color you are looking at. I actually did a little Flash experiment with the after image effect. You can adjust the color of the little design with the sliders, and the color of the background. Then click on the design to make it disapear. You can also change the design by hitting change.

http://web.syr.edu/~bmbilfie/swf/afterimagebg.html

edit: I also made one for the illusion of persistence of vision, when something is moving at a certain speed it appears there are more of what is actually there.

http://web.syr.edu/~bmbilfie/swf/perception.html