Cool Optical Illusion

From an email forward (Thanks Rybuoy!)

Take a look at the graphic below.
If your eyes follow the movement of the rotating pink dot, the dots will remain only one color, pink.

However if you stare at the black ' +' in the center, the moving dot turns to green.
Now, concentrate on the black '+ ' in the center of the picture. After a short period, all the pink dots will slowly disappear, and you will only see only a single green dot rotating.