Afterimages have also been used outside of contemporary art, such as in the "See No Evil" campaign by Amnesty International. This campaign features a series of billboards which initially depict seemingly unrelated black shapes. However, if we focus on the red cross for 30 to 60 seconds then look at a plain surface, we should be able to see the negative afterimage of the black shape, which should form the faces of various leaders from the United States, China, Russia, North Korea and Iran.