The face of a doll is clearly not human; the face of a human clearly is. Telling the difference allows us to pay attention to faces that belong to living things, which are capable of interacting with us. But where is the line at which a face appears to be alive? A new study published in Psychological Science finds that a face has to be quite similar to a human face in order to appear alive, and that the cues are mainly in the eyes.  credit: Psychological Science