The walking dead was the most popular TV drama in 2013, what is it about the half-human monstrosities called zombies that has enthralled audiences since the Night of the Living Dead in 1969? The glimmer of distorted humanity in zombies is perhaps their most disturbing feature. Mannequins, wax figures, and ventriloquist dummies all share a disturbing similarity to humans. The guttural dislike that people feel for things that appear too close to human was called the Uncanny Valley Effect by Japanese roboticist Masahiro Mori in 1970. Mori hypothesized that as robots become more humanlike they are more likable until a certain point when they appear too close to human but with subtle features that look wrong confusing the observer making them repulsive. He suggested the living dead would be the perfect example of the Uncanny Valley phenomenon.
A 2013 Japanese study examined a cognitive explanation for the Uncanny Valley effect in a series of experiments. Yamada, Kawabe, and Ihaya had participants identify pictures that were a mix of a person and a Charlie brown doll, or a cartoon person with varying degrees of each picture, for example one picture would be 20% human and 80% cartoon. Participants identified what the pictures were of, and the rated how much they liked the mixed pictures. The researchers thought that more mixed pictures would be harder for people to identify, so the mixed pictures would take longer to identify than pure ones. They also thought that difficulty identifying whether a picture was human would be uncomfortable making people dislike mixed pictures. Participants were significantly slower at identifying the mixed pictures than pure pictures, and they liked the mixed pictures less than the pure ones.
Does uncanny similarity between real and fake make us uncomfortable only when we see almost real humans, or could the effect generalize to other species? The researchers decided to test whether people would have the same reactions to pictures of dogs in their second experiment that they bad to humans in their first experiment. The pictures in the second experiment were mixed with various degrees of real dog and either a cartoon dog, or a stuffed Snoopy doll. Again participants had to identify the subject of the picture that they were shown, and then rated the likability of the pictures. The same results appeared using pictures of dogs that had appeared using pictures of humans. The mixed pictures took participants longer to identify, and were less likable. This means that the Uncanny Valley effect is not only applicable to things that look nearly human; identification difficulty can make anything less likable.
Categorization difficulty makes the almost human difficult to identify, and revolting. Part of the disturbing power of zombies in film is their resemblance to living things, the fear we feel is due to their eerie resemblance to humans. The next time that you encounter a wax museum, go inside and look closely at the figures. When you feel confused about whether the humanoid things you encounter are real, and revulsion at their waxy pallor and glazed expression, know that the feeling is called the Uncanny Valley effect.
Mori, M. (1970). The Uncanny Valley. Energy 7(4), 33-35.
Yamada, Y., Kawabe, T., & Ihaya, K. (2013). Categorization difficulty is associated with negative evaluation in the "uncanny valley" phenomenon. Japanese Psychological Research, 55(1), 20-32.