An Optical Illusion
If your eyes follow the movement of the rotating pink dot, you will only see 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 a green dot rotating.
It's amazing how our brain works.
There really is no green dot, and the pink ones really don't disappear.