The Uncanny Valley is an unproven hypothesis of robotics concerning the emotional response of humans to robots and other non-human entities. It was introduced by Japanese roboticist Masahiro Mori in 1970. It states that as a robot is made more humanlike in its appearance and motion, the emotional response from a human being to the robot will become increasingly positive and empathic, until a point is reached beyond which the response quickly becomes strongly repulsive. However, as the appearance and motion continue to become less distinguishable from a human being’s, the emotional response becomes positive once more and approaches human-human empathy levels.
This gap of repulsive response aroused by a robot with appearance and motion between a “barely-human” and “fully human” entity is called the Uncanny Valley. The name harkens to the notion that a robot which is “almost human” will seem overly “strange” to a human being and thus will fail to evoke the requisite empathetic response required for productive human-robot interaction.
The phenomenon can be explained by the notion that if an entity is sufficiently non-humanlike, then the humanlike characteristics will tend to stand out and be noticed easily, generating empathy. On the other hand, if the entity is “almost human”, then the non-human characteristics will be the ones that stand out, leading to a feeling of “strangeness” in the human viewer.
Another possibility is that affected individuals and corpses exhibit many visual anomalies similar to the ones seen with humanoid robots and so elicit the same alarm and revulsion. The reaction may become worse with robots since there is no overt reason for it to occur, whereas distaste for the sight of a corpse is an easy feeling to understand. Behavioural anomalies are also indicative of illness, neurological conditions or mental dysfunction and again evoke acutely negative emotions.
Some roboticists have heavily criticized the theory, arguing that Mori had no basis for the rightmost part of his chart, as human-like robots are only now technically possible (and still only partially). David Hanson, a roboticist who developed a realistic robotic copy of his girlfriend’s head, said the idea of the Uncanny Valley was “really pseudoscientific, but people treat it like it is science.” Sara Kiesler, a human-robot interaction researcher at Carnegie Mellon University, questioned Uncanny Valley’s scientific status, noting that “we have evidence that it’s true, and evidence that it’s not.”