Uncanny valley

In aesthetics, the uncanny valley is the hypothesis that human replicas which appear almost, but not exactly, like real human beings elicit feelings of eeriness and revulsion among some observers.Valley denotes a dip in the human observer's affinity for the replica, a relation that otherwise increases with the replica's human likeness. Examples can be found in robotics, 3D computer animations, and lifelike dolls among others.

The concept was identified by the robotics professor Masahiro Mori as Bukimi no Tani Genshō (不気味の谷現象) in 1970. The term was first translated as uncanny valley in the 1978 book Robots: Fact, Fiction, and Prediction, written by Jasia Reichardt, thus forging an unintended link to Ernst Jentsch's concept of the uncanny, introduced in a 1906 essay "On the Psychology of the Uncanny." Jentsch's conception was elaborated by Sigmund Freud in a 1919 essay entitled "The Uncanny" ("Das Unheimliche").

Mori's original hypothesis states that as the appearance of a robot is made more human, some observers' emotional response to the robot become increasingly positive and empathic, until it reaches a point beyond which the response quickly becomes strong revulsion. However, as the robot's appearance continues to become less distinguishable from a human being, the emotional response becomes positive once again and approaches human-to-human empathy levels.

This area of repulsive response aroused by a robot with appearance and motion between a "barely human" and "fully human" entity is the uncanny valley. The name captures the idea that an almost human-looking robot seems overly "strange" to some human beings, produces a feeling of uncanniness, and thus fail to evoke the empathic response required for productive human–robot interaction.

A number of theories have been proposed to explain the cognitive mechanism underlying the phenomenon:

A series of studies experimentally investigated whether Uncanny Valley effects exist for static images of robot faces. Mathur MB & Reichling DB used two complementary sets of stimuli spanning the range from very mechanical to very human-like: first, a sample of 80 objectively chosen robot face images from Internet searches, and second, a morphometrically and graphically controlled 6-face series set of faces. They asked subjects to explicitly rate the likability of each face. To measure trust toward each face, subjects completed a one-shot investment game to indirectly measure how much money they were willing to "wager" on a robot's trustworthiness. Both stimulus sets showed a robust Uncanny Valley effect on explicitly-rated likability and a more context-dependent Uncanny Valley on implicitly-rated trust. Their exploratory analysis of one proposed mechanism for the Uncanny Valley, perceptual confusion at a category boundary, found that category confusion occurs in the Uncanny Valley but does not mediate the effect on social and emotional responses.

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