In the optical illusion above, you can see, on a close-up view, an angry man on the left and a calm woman on the right. But when you stand farther back, the faces change expression and even genders! If you squint, blink, or defocus, an angry man should substitute for the face of the woman and the left angry face should not be angry anymore.
These kinds of illusions are called hybrid faces, and you can see a better and larger version of this picture at the link below.
This illusion was created by Dr. Aude Oliva and Dr. Philippe Schyns, and it illustrates the ability of your visual system to separate information coming from different spatial frequency channels.
