Ever find yourself staring at a picture like this one and wondering what is the main image? Do you see the people standing there? Or do you see several white columns? Or do you switch back and forth to see both? It kind of makes you feel dizzy as you stare at the image. These types of art work play tricks on our mind by using the principle of figure-ground perception. This means, at first when we look at this picture, we focus on what we think the main image is. Then, we ignore what seems to us to be the background. If we look at this picture as the people being the foreground, then we ignore the white background of the columns. Or we can look at this picture as the white columns being the foreground and the people being the background. Either way, we ignore a part of the picture. This idea of figure-ground perception leaves us staring at a picture and watching the images flip-flop. This perception principle also deals with the fact that, cognitively, we distinguish images by contrast. In this case, the black and white forms a contrast, allowing us to see if the white part is the main image or if the black part is the main image. This contrast allows our brain to see both images and to form images out of what would normally be just a series of squiggly lines. What image do you see?