If you stare at the black " + " in the centre, the moving dot turns to green. Now, concentrate on the black " + " in the centre 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.color, pink.

It's amazing how our brain works. There really is no green dot, and the pink ones really don't disappear. This should be proof enough, we don't always see what we think we see.