Here is some really surprisingly research coming out of the University of Queensland. While working on an unrelated project, researchers aligned a bunch of faces at the eyes. The surprise came when the faces were played back in succession while not looking directly at them. Viewed in the periphery, what you perceive is a procession of horrific, scary, monster-like faces. But stop the video on any one of them, and each turns out to be a pretty, pleasing face.
According to the researchers, Sean Murphy and Matt Thompson, what your brain keys on are all the specific differences between each face. As the center of your brain’s attention, those differences appear magnified and greatly distorted.
Watch this video twice. First do as it says, and keep your eyes on the cross. Note how ugly the faces are that go by. And then play it a second time, looking directly at the faces, and pausing it whenever you like. There is not an ugly one to be found.