In The Pixar Touch, I looked at how Pixar avoids the dreaded "uncanny valley" in its films--the feeling of revulsion that observers feel when seeing an image in which a human appears realistic, but not quite perfectly realistic.
Now two researchers have found that macaque monkeys experience the uncanny valley effect, too. Asif Ghazanfar and Shawn Steckenfinger of the psychology department at Princeton found that the monkeys had such reactions when looking at computer-generated images of not-quite-perfectly-realistic monkeys. The results suggest that the uncanny valley effect may have an evolutionary basis--but what is it?
From a summary of the research:
In the experiments, the monkeys, which normally coo and smack their lips to engage each other, quickly avert their glances and are frightened when confronted by the close-to-real images. When asked to peer at the less close-to-real faces and real faces, however, they viewed them more often and for longer periods.
Despite the widespread acknowledgement of the uncanny valley as a valid phenomenon, there are no clear explanations for it, Ghazanfar said. One theory suggests that it is the outcome of a "disgust response" mechanism that allows humans to avoid disease. Another idea holds that the phenomenon is an indicator of humanity's highly evolved face processing abilities. Some have suggested the corpse-like appearance of some images elicits an innate fear of death. Still others have posited that the response illustrates what is perceived as a threat to human identity.