Before you click on the link below to see the illusion, follow what the National Institute of Environmental Health Sciences website says to do:
"If you stare at the black "+" in the center, the moving dots turns to green.
Now, concentrate on the black "+" in the center 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."CLICK HERE to get the pink dots to rotate.
Image source: National Institute of Environmental Health Sciences