A sense of vague unease crawls through your mind as you notice that the reflection in your mirror doesn’t match your own face, or when a puppet keeps waltzing even after its strings have been cut. Then there's the android that smiles while its eyes stare unblinking into your own. These images of horror story fodder don’t rely on fear of the unknown, but of the almost known. Objects that evoke this reaction are said to fall into the “uncanny valley.”

The Valley Defined

Chip Sheffield, a professor of the College of Art and Design and faculty affiliate with the School of Individualized Study who created the course “Art and Technology: From the Machine Aesthetic to the Cyborg Age,” explained the origins of this term. According to Sheffield, the concept of the uncanny valley is credited to the Japanese roboticist Masahiro Mori.

“It really has to do with how we would respond to, say, a robot that had human-like attributes or human-like qualities, and the human-likeness of any given entity, and how humans respond to that entity. [Mori] proposes graphing this on an x- and y-axis,” Sheffield said.

Mori’s graph shows that human familiarity or comfort with something increases as it becomes more human-like, until the object reaches approximately 80 percent similarity to a human. At this point, there is a sharp drop-off in familiarity which rises up again as the entity approaches 100 percent human-like characteristics. The resulting shape is a valley.

David Simkins, an associate professor with the School of Interactive Games and Media, explained that the uncanny valley is a statistical average rather than an exact reaction experienced by all humans.

“Whenever you’re talking about the uncanny valley ... you’re talking about what people see and how it affects them,” Simkins said.

Because people react to perception in different ways, Simkins explained, there's some variation in how the uncanny valley affects individuals. However, the phenomenon usually evokes similar emotions.

“When we perceive something to be human-like or human, if something is just a little bit off about it, [then] we start to become really uncomfortable interacting with the thing, or being around the thing even," Simkins said. "It’s eerily not right, and that sense of it not being right creates anxiety.”

One factor that differentiates this phenomenon from other fear reactions is that its source is not always clear.

“The interaction with the uncanny valley happens before people are aware usually of what’s wrong. So they can identify that they don’t like the face or don’t like the thing, but they can’t necessarily tell you exactly what it is about it that torques them off. It’s deep in their perception,” Simkins said.

This inability to pin down exactly what is “wrong” heightens the sense of unease people experience when confronted with the uncanny. At times, they may not even think to look for the source of their anxiety.

As Sheffield put it, “we so rarely question, when we’re looking at another human face, whether that face is human or not.”

"We so rarely question, when we’re looking at another human face, whether that face is human or not."

Applied Horror

Once this phenomenon is understood, it can be intentionally avoided — or invoked.

“Good artists know how to use, and not unintentionally use, the uncanny valley,” Simkins said.

The ways that artists explore the uncanny valley phenomenon go beyond physical designs, he explained. While the uncanny valley has its roots in visual perception, the same idea of “uncanniness” can be manipulated in music, mood, story and character movement.

Sheffield also spoke about artistic examination of the uncanny, in addition to pointing out that awareness of the uncanny is critical in the fields of prosthetics and facial recognition.

One of the most popular areas for application of this concept is in the game industry — specifically in horror games.

“[Horror games] are a great place to use eeriness,” Simkins continued. “You want to make your player feel something is eerie, feel anxious, feel a little out of control and if you can ... trigger some of that anxiety before they even know why they’re anxious. That’s a great tool to use to try and get somebody in the mood to be frightened. That’s much of the trick of a horror game, is getting the player to get on board with being willing to be horrified.”

While many uncanny games have been created over the years, Simkins recommends “The Sinking City” and the “Silent Hill” series as particularly good examples of this phenomenon.

Cultural Relativity

“It is always important to realize that [the uncanny valley] is a sociobiological phenomenon, not just a biological phenomenon,” Simkins said.

"That’s a great tool to use to try and get somebody in the mood to be frightened."

This social aspect means that the uncanny valley relies heavily on cultural norms. Sheffield also emphasized this point, saying that the divide in eastern and western cultural approaches to robotics results in different levels of associated uncanniness.

Not only does the uncanny valley shift between different societies, but it can shift over time, both on an individual and cultural level.

“There’s some pushback on the uncanny valley because it’s not the only thing operating. For one thing, our perception is all socially based,” Simkins explained. “So when someone gets used to something, it no longer has that uncanny valley response to it."

In terms of more widespread changes, Simkins gave the example of how technological advancements in computer graphics led to an uncanny valley shift. Images and designs that were an accepted standard in the late 20th century are now often considered uncanny because most people are accustomed to a higher degree of realism.

Simkins suspects that this trend may continue as art becomes increasingly “cinema-realistic.” He predicts the valley will broaden over time as society grows uncomfortable with designs that aren’t either highly realistic or intentionally abstract.

Because of its cultural and individual relativity, the uncanny valley is a nebulous concept. Perhaps the best way to understand it is to experience it firsthand. If horror games and robotic realism interest you, maybe it’s time to take the metaphorical plunge down the slopes of the valley. The comforts of the familiar world will be waiting when you climb back out.