Looser and Wheatley do a nice study, reported in Psychological Science, on how we determine whether a face is dead or alive. A review of the work in Science Now has some nice videos of morphing faces along a gradient of animacy. The authors paired doll faces with a similar-looking human faces and used morphing software to blend the two, ending up with a spectrum of pictures that ranged from fully human to part human-part doll to purely doll. Volunteers consistently looked mainly at the eyes, and selected as the dividing point those faces that were about two-thirds along the continuum, closer to the human end. They also attributed the capability of thought to those faces.