Perhaps you see a glowing green square moving back and forth in the display above. If so, this is all your creation, not mine. All I've done is to put up 900 dots that never move. I just change the colors of some of the dots from red to green or from green to red. You create the glowing green square with its edges. You also create its motion. This display is one of the stimuli I use to study how human vision constructs the objects, surfaces, and colors that we see. For more you can see my paper on The interaction of color and motion or my forthcoming book Visual Intelligence.