What we see depends on what we look for

First, follow the movement of the rotating pink dot:

Next, stare at the + sign in the center of the image.

Finally, concentrate for at least one minute on that same + sign.

Most people will see only a pink dot in Step 1. In Step 2, most will see the moving dot turn green. And in Step 3, after a short period of time, many people will see the pink dots slowly disappear. Some will also see only a green rotating dot.