A green dot that rotates and “eats” the lilac dots. This is what some people claim to see by carefully looking at the image we discuss here. It is a very interesting optical illusion, able to “KO” our brain.
Think the GIF accessible at this link it’s called “Pac-Man Illusion”. The reason is to be found in the fact that, remaining with the gaze fixed in the center of the image (where the “viewfinder” is located) and trying not to make the slightest movement, the dots that rotate and disappear “in turn”, initially by lilac or magenta color, they change “suddenly”.
More precisely, at some point a green dot appears, which takes the place of the one that was previously “missing” and starts making all the lilac dots “disappear”, just as if it were a Pac-Man level. Staying for a while with the gaze fixed in the center of the GIF, the dots “disappear” one by one, until only the “nonexistent” green dot remains to rotate around the center. Seeing the green dot is “easy”, but some people have had to “focus” a little more to see the lilac dots “disappear”.
In any case, the reason this optical illusion occurs is due to the visual sensation called afterimage. Put simply, after a while our eyes “get tired”, coming to “process” the colors that are at the opposite end of the spectrum (in the case of the Pac-Man illusion, the green dot appears).
For the rest, the “disappearance” of the lilac dots is linked to the Troxler fade (you may remember this name due to another well-known optical illusion).