Very cool illusion

What colour is the rotating dot? If your eyes follow the movement of the rotating pink dot, you will
only see one color, pink. Now, concentrate on the black cross in the
center of the picture. After a short period of time, you’ll notice that the rotating dot changes colour to green! Wierd huh?

Thanks to Toni for the pic

If you find this stuff interesting, here’s some more Optical
Illusions and Visual Phenomena thanks to Dr
Michael Bach, who seems to specialise in this sort of thing.