The proposed dip in your affinity for a figure that is almost but not quite human — close enough to read as a person, wrong enough to read as a corpse. Mori held that movement deepens it: a lurching figure unsettles more than a still one.
Masahiro Mori, 1970.
// Where it sits
Affinity rises with realism, plunges just before the end, then recovers. The dip is very close to the finish line.
What it really means
The single most useful thing about Mori's 1970 essay is the example he actually used, because it is not the one anyone expects.
Not a robot face. Not animation. A prosthetic hand.
A prosthetic hand can be crude — obviously artificial, clearly a tool — and people are fine with it. Make it realistic: skin tone, fingernails, veins, the right weight. Now, when someone shakes it, they recoil. Mori's point is that the improvement made things worse — and when he asks why we should be equipped with the reaction at all, his own answer is that it is an integral part of our instinct for self-preservation.
Affinity rises with realism. Then, very close to the end, it plunges. Then it recovers on the far side. Hence valley — and it sits almost at the finish line, which is why getting better at this can make things dramatically worse before it makes them better.
The part that gets dropped is his claim about movement. Mori argued that motion amplifies both the peaks and the valley — it deepens the dip. Which is why a still render of a digital face can look perfectly acceptable and the same face in motion is unbearable. A still image is the weakest case for the effect, not the strongest, and almost every modern discussion of the uncanny valley uses still images.
One more thing worth knowing, because it changes how the term feels. 'Uncanny' is a translation artefact. Mori's Japanese phrase means roughly eerie valley. The 1978 English rendering chose uncanny, which dragged in a whole philosophical tradition — Jentsch, Freud, the unheimlich — that Mori was not invoking. The word acquired a psychoanalytic pedigree at the border, in translation, the same way ego did.
And the hypothesis itself remains contested: possibly generational, possibly cultural, possibly not one phenomenon at all. Which is fine. It has been one of the most productive wrong-or-right ideas in the field for more than fifty years.
Where it comes from
The English word 'uncanny' imported Freudian and Jentschian baggage that Mori's Japanese never carried — a documented translation artefact from the 1978 rendering.
Myths & misconceptions
Mori was writing about CGI and photorealism.
His running example was a PROSTHETIC HAND, and his central claim is about MOVEMENT: motion changes the shape of the graph by amplifying the peaks and the valleys. A still image is the weakest case for the effect, not the strongest.
The valley is settled science.
There are ongoing challenges — that the effect may be generational, culturally variable, or an artefact of information processing rather than one unified phenomenon. It is an extremely productive hypothesis rather than an established law.
Compare & contrast
Uncanny valley vs AI slop
Slop is judged by effort and volume; the uncanny valley is a perceptual response to near-miss humanity. A beautifully crafted android can sit deep in the valley. Most slop never gets close enough to fall in.
| // | Uncanny valley | AI slop |
|---|---|---|
| Judged by | Perception | Process |
| Requires craft | Yes | No |
| Named | 1970 | 2024 |
| Feeling | Dread | Contempt |
How it connects
- Liminal Spacethe other aesthetic built on almost-rightness rather than wrongness.
- Ai Slopthe modern material most often described with this word, usually inaccurately.
Tell it apart
Questions people ask
- Who coined it?
- The roboticist Masahiro Mori, in a 1970 essay in a Japanese magazine.
- Is 'uncanny' a good translation?
- It is literal but loaded. It pulled in Jentsch's and Freud's philosophical concepts of the uncanny — an association Mori's Japanese phrase, which means roughly 'eerie valley', did not carry.
- Does movement matter?
- Enormously. Mori argued motion amplifies both the peaks and the valley — which is why a still render can look fine and the same face in motion can be unbearable.