The Uncanny Valley

by stephenpalmersf

The uncanny valley is a human cognitive phenomenon in which robotic or CGI human-like creations which are very realistic, yet not so accurate they are indistinguishable from reality, elicit feelings of disgust or eeriness in the observer. The phenomenon has been known for a few decades since being reported by a Japanese robotics engineer. Many directors of animated films now have to make a decision between ‘obviously animated’ human characters and 100% realistic in order to avoid their audiences being repelled by what they see. This is the reason for the notably ‘cartoonish’ quality of many modern CGI animations, for example The Incredibles.

There are a number of hypotheses as to what might be causing the uncanny valley effect, for instance disgust helping to avoid bugs and germs (i.e. originally evolving to help avoid potential sources of pathogens), or as a threat to our distinctiveness (the more a robot resembles a real human the more it represents a challenge to our social identity – there is also a hypothesis based in the same thing on religious grounds). Then there is an interesting hypothesis based on violation of our psychological norms, i.e. if an robot appears sufficiently nonhuman its human characteristics become noticeable, which brings empathy; if the robot looks almost human its nonhuman characteristics become more noticeable, giving us the uncanny sense of strangeness: repulsion. A related theory concerns the conflict of perceptual cues, i.e. the repulsion or eeriness associated with uncanny feelings is produced by a conflict in cognitive representations, uncanniness happening when somebody perceives conflicting psychological categories; for instance when a mostly accurate humanoid figure moves like a robot, or has other obvious robotic features.

Much discussion surrounds these various hypotheses, and none are generally accepted. Some have a lot of evidence weighing against them.

As a reader of books about human evolution, I would like to add my own hypothesis. It seems to me that the uncanny valley effect is strong and universal, and therefore must have an evolutionary basis. There are similarities between it and emotion, which has a deep evolutionary history and is essential to the conscious mind. It must be a cognitive effect, perhaps because modern human beings (homo sapiens) are profoundly aware of and sensitive to faces. Infants recognise faces at an incredibly young age. So, given that our consciousness is rooted in empathy – in our use of ourselves as psychological exemplars by which to understand the behaviour of others – it strikes me that if, during the evolution of homo sapiens, we encountered species remarkably similar to ourselves yet not quite the same, there would perhaps be an eerie, uncanny, negative effect. This effect would have evolved in homo sapiens specifically to keep similar species apart.

Of course, it could be argued that there was no particular need to keep similar species apart. We now have proof that interbreeding took place between Neanderthals and homo sapiens, with about 1%-4% of non-African human DNA being Neanderthal. Our species coexisted in Europe; that arrangement however, judging by the archaeological evidence, was more like a mosaic than any other arrangement.

But what if the need for species separation was cognitive and could be acted upon by Darwinian natural selection? Nicholas Humphrey in Soul Dust convincingly argues that for consciousness to evolve to the degree present in us it must be highly visible to natural selection; in other words, there must be a strong selection pressure in favour of consciousness, with natural selection acting upon cognitive attributes once the expansion of the neocortex is well underway. Perhaps that selection pressure not only brought consciousness to homo sapiens, it also created a cognitive abyss – a kind of abstract version of the species abyss across which no fertile offspring can be created – which the various psychological world-views could not bridge. Such an inability to bridge the cognitive gap would be felt – as an emotion is felt – by homo sapiens: the uncanny valley.

Perhaps our modern robots have accidentally stimulated this ancient cognitive effect, returning the eerie feelings of the uncanny valley to homo sapiens.

  • Update 04/04/19.
  • This is an excerpt from Chris Stringer’s excellent book The Origin Of Our Species:
  • If and when modern humans encountered Neanderthals, how much would behavioural differences between them have affected the way they saw each other? Would they have perceived each other simply as other people enemies, or even the next meal? … These populations had been diverging from each other for much longer than any modern human groups who encountered each other in the Americas and Australia during the colonial ‘Age of Discovery.’ In my view there were probably deep differences in appearance, expression, body language, general behaviour, and perhaps even things like smell, which would have impinged on how the Neanderthals and Cro-Magnons perceived each other.

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