Last year, University of Queensland psychology undergraduate Sean Murphy was collecting images of faces while preparing an experiment. As he skimmed through them, he noticed that they began to appear grotesque and deformed, though when viewed individually they appeared normal and even attractive. (The demonstration above uses photographs of celebrities.)

“The effect seems to depend on processing each face in light of the others,” writes grad student Matthew Thompson, who published the result last year with Murphy and Jason Tangen. “By aligning the faces at the eyes and presenting them quickly, it becomes much easier to compare them, so the differences between the faces are more extreme. If someone has a large jaw, it looks almost ogre-like. If they have an especially large forehead, then it looks particularly bulbous. We’re conducting several experiments right now to figure out exactly what’s causing this effect.”

(Tangen, J. M., Murphy, S. C., & Thompson, M. B. (2011). Flashed face distortion effect: Grotesque faces from relative spaces. Perception, 40, 628-630.)