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Look closely at the central cross. The missing dot revolves around the circle, but after some time this dot turns green. However, in reality there is no green dot in the image.


This illusion works well with pink dots on a gray background because there is a low contrast between the two colors. Black dots on a white background, so higher contrast, your brain would find it harder to ignore the black dots.  


See the green dot spinning around? This is called an 'after-image'. The light receptors in your eyes are sensitive to red, blue and green colors. When you look at the pink dots for a longer period of time, your red light receptors get "tired". They are used to the pink color. When the dot has already disappeared, your 'red' receptors temporarily don't work as well and they only send a weak signal to your brain.  


The surrounding receptors that don't respond to the pink color aren't tired and still send a strong signal to your brain. The information from all your other color receptors is not balanced, so that's why you see these differently colored "after images".

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