Uncanny valley 

Uncanny Valley

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The uncanny valley is a term used to refer to the familiar, disturbing impression people have when a robot resembles a human being very closely but is not convincingly realistic [1]. The phenomenon first emerged in the 1970s. Japanese roboticist Masahiro Mori observed that robots became more interesting the more they resembled humans in appearance. However, this tendency holds only up to a certain point. He then described this phenomenon as bukimi no tani (English: uncanny valley). After ‘reaching’ bukimi no tani, interest turns into alienation, anxiety or even fear [2].

Fig. 1. Diagram illustrating the uncanny valley phenomenon. 

Source: https://www.linkedin.com/pulse/uncanny-valley-personalization-mac-reddin-/  

Why do we experience the uncanny valley?

We have yet to find one concrete answer to this question. However, several theories help us better understand why it occurs. These reasons are divided as follows:

  • Neurological

In a 2019 study, Fabian Grabenhorst and a team of neuroscientists analysed the neurological aspect of the uncanny valley. They investigated brain patterns in 21 people using functional magnetic resonance imaging (fMRI), a technique that measures changes in blood flow in different brain areas. During the tests, participants determined their confidence level towards humans and robots with varying levels of human similarity. The results showed that some specific parts of the brain were particularly important for the uncanny valley. Two parts of the medial prefrontal cortex, responsible for attention and senses, showed unusual activity. One of them transformed the ‘human resemblance signal’ into a ‘human detection signal’ and overemphasised the boundary between human and non-human. On the other hand, the other correlated this signal with a sympathy rating. This combination formed a mechanism that closely resembles the uncanny valley phenomenon.

  • Psychological

It turns out that as early as 1919, Sigmund Freud observed a phenomenon he described as ‘a strange emotion felt by people which is aroused by certain objects’. He suggested that the feeling we then experience may be related to doubts about whether something inanimate has a ‘soul’. Interestingly, at the time, his observation obviously referred not to robots but realistic dolls or wax figures. He suggested that the phenomenon may be older than we think and pertain to more things than just machines. Today, the film industry uses a similar mechanism. Many horror films give human characteristics to characters that are not human.

  • Evolutionary

The uncanny valley can also be linked to evolution. The robots we classify in the uncanny valley look like humans but also have features that are clearly not human. Some of these features, such as lifeless skin, unnatural facial features or a voice that does not match their appearance, can make us associate them with something outside the norm or even dangerous. This, in turn, creates aversion or fear in us. When we are confronted with something that is human, but unrealistic, not ‘like a living thing’, it evokes a feeling similar to the one we experience when we come into contact with something that is dead.

  • Cognitive

The uncanny valley may also stem from an existential fear of robots replacing humans. The sight of a robot that resembles a human in appearance but is not human disrupts our expectations of what a human looks like versus what a robot looks like. It raises doubts about who humans are, what they should look like, and how they should behave. It is worth noting that the anxiety does not stem from the mere existence of robots but from the existence of such robots that combine elements that do not usually occur together. For example, robots that ‘sound like robots’ are not a problem for us, while robots with a human voice are [2, 3].

The uncanny valley in reality

The uncanny valley is present in many different areas. Outside robotics, it can also be observed in computer games or films that use computer-generated imagery (CGI). This effect goes beyond technology and can be caused by objects such as realistic dolls, mannequins or wax figures.

  • Sophia

Photo 1. Photo of the Sophia robot. 

Source: https://pl.wikipedia.org/wiki/Plik:Sophia_%28robot%29.jpg  

Sophia is the most advanced humanoid robot yet developed. Created by Hanson Robotics, it was first activated in 2016. Sophia was granted citizenship of Saudi Arabia, thus becoming the world’s first robotic citizen. The robot was awarded the title of Innovation Champion of the United Nations Development Programme. Sophia has also gained recognition through appearances on TV programmes such as Good Morning Britain and The Tonight Show [4]. Sophia can express various complex emotions, assume human facial expressions and interact with others. The robot is equipped with the ability to process and use natural language, facial recognition and visual tracking [5]. Sophia’s ‘skin’ is made of a special material developed by researchers at Hanson Robotics, which has been named Frubber. It is a type of rubber that resembles human skin’s texture and elasticity [6]. Because of its appearance and behaviour, which are very close to those corresponding to humans, it is still too unnatural. Sophia is the case of the uncanny valley and can thus arouse discomfort and anxiety.

  • The Polar Express

Fig. 2. Computer-generated shot from The Polar Express

Source: https://collider.com/worst-cases-of-uncanny-valley-movies/ 

The Polar Express is a 2004 animated film directed by Robert Zemeckis. This film was made using CGI, which many believe was misused. The producers of the film adaptation themselves had conflicting visions of how the film should be made. In an interview with Wired, Robert Zemeckis said that ‘live action would look awful, and it would be impossible – it would cost $1 billion instead of $160 million.’ In contrast, Tom Hanks, who played seven characters in the film, argued that the film should not have been made as animation [7]. The filmmakers found a kind of consensus by combining the two approaches. They used motion capture, a method of recording actors’ movements and then transferring them to a computer. However, critics argue that the filmmakers failed to represent the characters well, making them seem insufficiently realistic. The characters lack human emotions and facial expressions; they move unnaturally, and their gaze seems constantly ‘absent’.

Consequences of the uncanny valley

The uncanny valley significantly impacts the future of many different areas of our lives. With the existing knowledge of the unwanted feelings it can cause, roboticists, filmmakers and video game designers can factor this problem into their work. It is clear now that there is value in developing robots that do not create mistrust between the machine and the user. Otherwise, they will be exposed to poor reception and less usefulness in achieving their intended purpose.

In films, on the other hand, overly realistic computer-generated characters can, at best, elicit a lack of sympathy from the viewer and, at worst, feelings such as anxiety or even fear. This is why filmmakers often overemphasise certain characters’ physical characteristics. Giving characters distinctive traits such as outsized eyes, unnatural skin colour, or overly dynamic movements is one way of dealing with avoiding the effect caused by the uncanny valley. Similar mechanisms are used in computer games; designers may want to create characters that are not overly realistic to avoid an unfavourable reception from players. However, there are also exceptions; in some cases, filmmakers or game designers may want to get characters that deliberately fit into the uncanny valley. In this way, they can control, for example, how villains will be perceived. A protagonist who exhibits some unnatural and overly realistic characteristics will create a sense of resentment among the audience [8, 9].

The uncanny valley and UX

A very interesting issue in the uncanny valley is its impact on user interface design. Adding certain realistic elements to the interface design can have positive effects. For example, light and shadow lend a sense of being able to press an item, and sound can provide a counterpart to a particular sound that we would also hear in real life. However, adding too much realism can lead to too thin a line between the virtual and the real. For example, a highly detailed calendar application whose texture resembles natural paper. The fact that we cannot touch it but only ‘scroll’ through it on a computer or smartphone screen can give us the impression of something strange, ‘not right’. This is why it is so important not to strive for elements that completely mirror real objects. By striking the right balance between realism and fiction, the user experience becomes enjoyable and dilemma-free [10].

Fig. 3. A very realistic Google Chrome logo from 2008 and its upgraded, much less realistic version from 2011. 

Source: https://bpando.org/2011/03/17/the-new-chrome-logo/  


People experience anxiety when encountering almost realistic-looking but still insufficiently realistic human-like entities; this phenomenon is called the uncanny valley. It is critical in various areas. Some examples include advanced robots, computer-generated characters or even forms beyond the realm of technology, such as dolls or wax figures. The implications of the uncanny valley can significantly affect the acceptance and usability of technology. In the context of UX, awareness of the uncanny valley is crucial for designers who seek to minimise undesirable effects by designing interfaces appropriately so that users feel comfortable and engaged in their interactions with products.


[1] https://www.techtarget.com/whatis/definition/uncanny-valley  

[2] https://spectrum.ieee.org/what-is-the-uncanny-valley  

[3] https://www.sciencefocus.com/news/uncanny-valley-what-is-it-and-why-do-we-experience-it  

[4] https://aidriven.pl/ai/etyka-i-prawo/robot-sophia-jak-humanoidy-zmieniaja-nasze-postrzeganie-ai/ 

[5] https://robotsguide.com/robots/sophia 

[6] https://www.hansonrobotics.com/the-making-of-sophia-frubber/ 

[7] https://faroutmagazine.co.uk/the-disturbing-valley-robert-zemeckis-polar-express/  

[8] https://www.techtarget.com/whatis/definition/uncanny-valley  

[9] https://www.verywellmind.com/what-is-the-uncanny-valley-4846247 

[10] https://cassidyjames.com/blog/uncanny-valley-curve/