Assalamualaikum and Greetings..
As we all knew, brains control most of the activities in our life. Thus, let's check wheter your brain work normally or not. ^_^
If your eyes follow the movement of the rotating pink dot, the dots will remain only one color, pink.
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.
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.