What to Know About The Uncanny Valley

Think about the animated movies you've seen. Did any of them have an animation style that was realistic but, at the same time, ended up making you feel super uneasy? The uncanny valley is a term used to describe the relationship between the human-like appearance of a robotic object and the emotional response it evokes.

One of the most classic examples is the 2004 movie Polar Express. Video games are a major player in the uncanny valley department too, as are humanoid robots. In this phenomenon, people feel a sense of unease or even revulsion in response to humanoid robots that are highly realistic. 

The uncanny valley has implications within the field of robotics and artificial intelligence. Devices and online avatars that are made to mimic the human experience may actually end up alienating people who are using such tools. 

Origins of the Uncanny Valley

The phenomenon was first coined and described by the Japanese roboticist Masahiro Mori in an article published in 1970. Mori identified the phenomenon as bukimi no tani genshō, meaning 'valley of eeriness.' In 1978, author Jasia Reichardt translated the term 'uncanny valley' in the book "Robots: Fact, Fiction, and Prediction."

In his work, Mori noted that people found his robots more appealing if they looked more human. However, this only worked up to a certain point. Once the uncanny valley has been reached, people feel uneasy, disturbed, and also sometimes feel afraid. 

In his seminal paper on the topic, Mori explained:

Mori used several examples to clarify this idea. An industrial robot has little human likeness and therefore generates little affinity in observers. A toy robot, on the other hand, has a more human likeness and tends to be more appealing. A prosthetic hand, he noted, tends to lie in this uncanny valley—it can be highly lifelike yet generates feelings of unease. 

Uncanny Valley Examples

The uncanny valley has been observed in a variety of contexts, from highly realistic robots to video game characters. Some of the best-known examples of the uncanny valley can be seen in movies. These include:

The Polar Express

The 2004 children's Christmas movie The Polar Express is an example of the uncanny valley effect. The film was made during an era of rapidly evolving computer-generated imagery (CGI) and animation technology but, unfortunately, the tools were yet to be refined. The computer-generated faces are close to lifelike in many ways, but their facial expressions are slightly off and inaccurate in an unsettling way.

Final Fantasy

The 2001 movie Final Fantasy: The Spirits Within showcased some of the most realistic CGI animation at that time. Despite efforts to make the animated characters appear super-realistic, the movie was a flop. Its commercial failure at the box office is often attributed to the uncanny valley. Simply put, people didn’t want to watch the movie because they found the animation disturbing.

Shrek

Early test screenings of the film Shrek elicited unexpected feelings of anxiety in children in response to the character Princess Fiona. She was simply too lifelike, causing kids to feel unnerved and even frightened, many crying whenever she appeared onscreen.

Based on the responses and feedback, the filmmakers edited Fiona's appearance before the film's theatrical release to give her a more cartoon-like appearance and prevent the uncanny valley effect.

Cats

The 2019 film adaptation of Cats featured humanoid felines that many people found unsettling. While some reportedly found the effect humorous, others reported feeling downright revolted. On social media, many viewers described the film as weird, creepy, and even induced nightmares. 

The fact that the film relies so heavily on movement may have also played a role in the audience’s reaction. Mori has proposed that the addition of motion can amplify the uncanny valley effect and, in this case, the film includes both human-like movements and cat-like motions that serve to further confuse the viewer.

What Causes the Uncanny Valley Effect?

There have been a number of proposed explanations for why people experience the uncanny valley effect, but no consensus has emerged. Some theories suggest that the phenomenon is biological, while others propose cultural explanations. Here are some factors that may play a role.

Ambiguity

Some suggest that the sensation of being “creeped out” is often caused by a sense of ambiguity. When we see things that are almost but not quite human, it creates a tension that feels unpleasant.

Such effects are sometimes exploited to heighten the horror or creepiness in movies. Horror films, for example, often infuse human characteristics into non-human entities including dolls (Annabelle) and clowns (It) to terrify audiences.

Mismatched Elements

Research has also shown that people tend to be disturbed when elements that normally don’t occur together are combined. For example, an article published in the journal i-Perception reports that while people are not disturbed by robots with “robot” voices or people with human voices, they do feel creeped out by robots with human voices. 

Inconsistency

Even in highly realistic depictions, people are adept at spotting the smallest inconsistencies in a robotic or animated humanoid. These relatively minor divergences can make a character go from lifelike to uncanny. In one of Mori’s original examples, a robotic character was seen as unlikeable and creepy when it smiled slightly too slowly.

Survival Response

Mori and others have suggested that the uncanny valley is an aversive, evolved response to the potential threats of death and disease. Because something is human-like but not quite lifelike, it may evoke the same response that people feel when they encounter something that is dead or dying.

Category Uncertainty 

Theories also suggest that the uncanny valley may exist due to the difficulty in determining what category an entity belongs to. Human and nonhuman represent two separate and mutually exclusive categories. So, when something approaches a point where it seems to transition from one to the other, it can trigger feelings of cognitive dissonance.

When people hold conflicting beliefs, they tend to experience feelings of psychological discomfort. In this case, there is a conflict between the belief that an entity is human and the belief that it is not human. Something that looked human might abruptly appear nonhuman, or it may even shift back and forth as the viewer observes it.

This mismatch between what you are seeing and your expectations may make you feel ambivalent or even threatened. In other words, it creeps you out.

Research on the Uncanny Valley

While Mori first proposed the theory in 1970, formal empirical investigations did not begin until the mid-2000s. Some research has supported the existence of the valley, although findings of how and why it happens are mixed.

Likeness and Eeriness

A 2013 study examined the relationship between human likeness and eeriness and found evidence supporting the existence of the uncanny valley. The researchers noted a linear relationship between likeness and eeriness when manipulating facial proportions and realism.

Children's Responses

A 2014 study found that children between the ages of 9 and 11 were also prone to experiencing feelings of uncanniness in response to human-like virtual characters. Virtual human-like characters were seen as being more strange and less friendly. 

Interestingly, these feelings of unease were more pronounced in instances where the characters lacked upper facial expression. Startled facial expressions were also more likely to be perceived as uncanny.

Uncanny Valley vs. a Wall

While some research has supported Mori’s original hypothesis, others have characterized the phenomenon as more of a cliff or a wall than a valley. In other words, rather than ever rising to the other side of that valley, likeability may simply drop off once a robot reaches a certain degree of realism.

Can It Be Prevented?

Not everyone agrees that the valley itself truly exists. For example, one of the earliest scientific investigations on the phenomenon was conducted in 2005 and concluded that the eerie feeling people experience has more to do with poor design and aesthetics, something that can occur at any level of realism.

Implications of the Uncanny Valley

The uncanny valley has a number of implications in various fields. These include:

Robotics 

As people rely more and more on robotic technology, it is important to design devices that do not create uneasiness or distrust. This is particularly true in the development of assistive technologies designed to help people with limitations perform tasks and interact with their environments.

People are more likely to be receptive to designs that are both useful and appealing. Designs that fall into the uncanny valley are likely to be poorly received and utilized less frequently. 

Digital Avatars 

These representations are used in a number of areas, including online customer service and online therapy. In online therapy, digital representations are often utilized to facilitate virtual communication between therapists and clients, particularly in situations that involve online chat or email communication.

When effectively used, avatars may help promote the therapeutic relationship. However, overly realistic depictions may interfere with the process.

For example, one study found that robots that look too human-like were often rated as being not only less likable but also less trustworthy, which would pose considerable problems in a therapeutic context since trust is so important to the success of treatment.

Film

Blockbuster films increasingly rely on CGI effects. At the same time, filmmakers have continued to work toward developing realistic computer-generated animations that blend seamlessly and don't provoke the uncanny valley.

Game Design

The uncanny valley can also have an impact on how players react to realistic characters in video games. In some cases, designers may take advantage of the uncanny valley to create a sense of dyspathy for villainous characters.

Criticisms of the Uncanny Valley

The uncanny valley concept has also been the subject of some criticism. 

Age May Play a Role

Some propose that the phenomenon is more common in older generations while younger people who grew up seeing robotics and CGI effects may be less likely to experience it. Yet research suggests the opposite, that older adults prefer more human-like robots than younger adults. Further research is needed to determine if age might have an effect.

The Effect Is Highly Varied

Other critics have noted that the uncanny valley effect happens in different situations and affects different senses. The heterogeneity suggests that each unique situation where it occurs may have different causes.

Avoiding the Uncanny Valley

As robots become increasingly important in everyday life, researchers and designers are interested in finding ways to create tools that will not fall into the uncanny valley. This may involve making robotic devices even more realistic so they move beyond the valley and appear more likable. 

Researchers have also proposed several design principles that may help animators and roboticists avoid uncanny effects. This includes:

• Matching human proportions with realistic textures
• Not mixing nonhuman and human elements
• Ensuring that behaviors, appearance, and abilities do not conflict

Another approach is to develop tools or devices that do not seek to mimic a human appearance. By relying on a non-human design, the device may be more appealing without running into the risk of alienating or even revolting those who interact with robotic devices.

In an interview with Wired, Mori stated that while it may be possible to bridge the uncanny valley, he sees no point in trying. Instead, he advocates designing things that stop before they reach the point of uncanniness.

Final Thoughts

More research into the phenomenon of the uncanny valley can provide more information about it, why it happens, and how to overcome it. In an interview with IEEE Spectrum, Mori stated that his original observation was intended to be more of a guideline for designers rather than a scientific statement. 

As technology continues to advance, it is possible that robots and digital animations could become so realistic that they blend with reality to the point where people don't experience discomfort or anxiety. For now, robots, digital avatars, and online animations will continue to become an increasingly common part of everyday life, making it important for designers to consider the audience's emotional response.