If your eyes follow the movement of the rotating pink dot, you will only see one color: PINK
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 of time, 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.
This gif prove the chinese famous saying: 凡事不要只看表象