MIT vision scientist Aude Oliva and University of Glasgow researcher Philippe Schyns created this illusion by producing hybrids of two images.  The left picture shows Dr. Angry, and the picture on the right Mr. Calm. But if you step away from your computer screen you will see that appearances can be deceiving. Nice Mr. Calm becomes Dr. Angry, and that nasty Dr. Angry turns out to be a pretty decent fellow after all. Fine details are blurred away as you step back, leaving you with only the overall shapes and shadings of the images: what vision scientists refer to as the low spatial frequency content of an image. When you step up close again, the images are once again dominated by their fine details, which are referred to as high spatial frequencies.  The illusion works because the left face is composed of a high spatial frequency angry face with a calm face in low spatial frequencies. The right face is exactly the opposite. When the images are blurred (by stepping away) the different layers of the hybrid are revealed.