uncanny valley
In plain wordsThe eerie feeling people get from robots, dolls or computer-made faces that look almost, but not quite, human: liking grows with human likeness, then suddenly plunges.
The hypothesized dip in people's affinity for an artificial figure — robot, prosthesis, doll, animated or AI-generated character — as it approaches but falls short of human likeness: affinity rises with human likeness, plunges into eeriness or revulsion when a figure is nearly human but subtly wrong, and recovers only at full human likeness. Masahiro Mori sketched it as a curve with a corpse and a zombie at the bottom, and argued that movement deepens the valley: a realistic prosthetic hand that moves stiffly is more unsettling than a still one. Proposed explanations include perceptual mismatch between realistic and unrealistic cues, uncertainty about category (human or machine), reminders of death and evolved disease avoidance. Empirical support is mixed: many studies find a dip for some stimuli, but its shape, causes and persistence with familiarity are disputed. The idea shapes robot design, animation and video games and, increasingly, reactions to AI-generated video, avatars and voices; many humanoid robothumanoid robot, n.: A robot built roughly in human shape, with a head, torso, two arms and usually two legs, so that it can work in spaces and with tools designed for people. makers choose stylized faces partly to avoid it.
The demo avatar was technically impressive but sat right in the uncanny valley.
Origin
Proposed by the roboticist Masahiro Mori of the Tokyo Institute of Technology in the 1970 essay 'Bukimi no tani' in the Japanese journal Energy. The English phrase appears in Jasia Reichardt's Robots: Fact, Fiction, and Prediction (1978); translations by Karl MacDorman with Takashi Minato (2005) and with Norri Kageki (2012, authorized by Mori) and press coverage of computer-animated films from 2001 popularized it.
Usage note
Mori's curve was a thought experiment, not a fitted dataset. His Japanese term for the vertical axis, rendered 'familiarity' in early translations and 'affinity' in the authorized one, has no exact English equivalent, which complicates comparisons across studies.
Related
- humanoid robothumanoid robot, n.: A robot built roughly in human shape, with a head, torso, two arms and usually two legs, so that it can work in spaces and with tools designed for people.
- anthropomorphismanthropomorphism, n.: Treating something that isn't human — a pet, a car, a chatbot — as if it had human thoughts, feelings or intentions. AI that talks fluently makes this temptation unusually strong.
- human–robot interactionhuman–robot interaction, n.: The study of how people and robots communicate, cooperate and share spaces, and of how to design robots that people find safe, understandable, trustworthy and pleasant to live or work with.
- deepfakedeepfake, n.: A fake but realistic video, photo or voice recording made with AI that puts words in a real person's mouth or shows them in a scene that never happened.
- AI companionAI companion, n.: A chatbot designed to be a friend, partner or confidant rather than a tool: it remembers you, has a personality and keeps up an ongoing relationship.
Sources
- Mori, M. (1970). Bukimi no tani [The uncanny valley]. Energy 7(4), 33–35.
- Mori, M. (2012). The uncanny valley (K. F. MacDorman & N. Kageki, trans.). IEEE Robotics & Automation Magazine 19(2), 98–100; republished online by IEEE Spectrum, 12 June 2012. spectrum.ieee.org/the-uncanny-valley
Mentioned in
humanoid robothumanoid robot, n.: A robot built roughly in human shape, with a head, torso, two arms and usually two legs, so that it can work in spaces and with tools designed for people., AI handsAI hands, n.: The tendency of early AI image generators to draw hands badly — extra or missing fingers, twisted joints — which became a running joke and a quick way to spot fake images., clankerclanker, n.: A slang insult for robots and AI systems, borrowed from Star Wars, that went viral in 2025 as a way of expressing annoyance at, or rejection of, AI., Frankenstein complexFrankenstein complex, n.: Isaac Asimov's name for the fear that intelligent machines will turn on the people who made them, after Mary Shelley's novel about a scientist destroyed by his own creation., human–robot interactionhuman–robot interaction, n.: The study of how people and robots communicate, cooperate and share spaces, and of how to design robots that people find safe, understandable, trustworthy and pleasant to live or work with., Will Smith eating spaghettiWill Smith eating spaghetti, n.: A grotesque 2023 AI-generated video of actor Will Smith eating spaghetti that became a meme and an informal yardstick: each new video model is judged by how well it redoes the scene.