How the Uncanny Valley Works

Visiting the Uncanny Valley
Roboticist Hiroshi Ishiguro (L) created an extremely lifelike android replica of himself. Alessandra Benedetti - Corbis/Corbis via Getty Images

Objects that mimic humans have a much longer history than the concept of the uncanny valley. Consider incredibly realistic sculptures like Michelangelo's Pietà. We have admired the skill of artists and the realism and emotion depicted in works of art for centuries, but perhaps because they are static and often uncolored, they don't seem to attempt to replicate humans exactly and don't unnerve us. Contrast this to the works of artist Ron Mueck: sculptures of humans that are fully painted and appear astonishingly lifelike. Although he often creates fantastic figures that are enormous or have fantastic features, even his works depicting mundane scenes (two old women talking, a couple lying in bed) have a disturbing effect. Mueck seems to intentionally exploit the uncanny valley effect in his art. Other examples of this intentional horror effect can be found in some Japanese horror movies, such as the unnatural movements of humanlike figures in "Kairo" and "Ringu."

Yet, when Mori first proposed the uncanny valley, there weren't any real-world examples of hyper-realistic robots or computer-generated characters. Since then, advances in robotics and computer graphics have made the uncanny valley a phenomenon we've increasingly encountered. The 2001 movie "Final Fantasy: The Spirits Within" featured ultrarealistic computer-generated images and characters, attempting to make them as lifelike as possible. And the aforementioned "The Polar Express" and 2007's "Beowulf" both were criticized for the creepiness of their not-quite-human characters. (They also helped popularize the uncanny valley concept in the U.S.)

More recently, the Star Wars movie "Rogue One" used computer-generated characters in place of the actors Peter Cushing (playing Grand Moff Tarkin) and Carrie Fisher (Princess Leia). They were generally more well-received than earlier CGI characters, possibly due to their limited screen time, and possibly because advances in computer animation helped pull them partly out of the uncanny valley.

Then there are androids. Advances in software, materials and electronics mean they're no longer confined to science-fiction movies. The most realistic androids today are art projects like "Nova Phil," a very realistic replica of science-fiction author Philip K. Dick by Hanson Robotics, or as technology demonstrations, like the Actroid robots built by Japanese company Kokoro. These androids have been tested as automated guides at public events and as telepresence robots, allowing for semi-direct interaction with someone who is in another location. For instance, roboticist Hiroshi Ishiguro's android replica can represent him while he teaches his university classes from a distant place. The verisimilitude of these robots drags them closer to the uncanny valley.

Will we be treated by android doctors tomorrow? Probably not, but that future is likely decades away rather than centuries. The implications of the uncanny valley will become even more important as robots and androids play larger roles in our lives.

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