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.

Concentrate on the black + in the center of the picture. Don't let your eyes look at anything else but the +. 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 is proof enough; we don't always see what we think we see.