A few weeks ago, a startling new image started circling around the internet. It was originally taken in 2016 but went viral after being posted on Reddit and YouTube in July this year. It’s a sculpture produced by the Japanese special effects company Link Factory that’s been nicknamed “Momo.”

Momo has since become associated with online creepypasta culture, but why is she so creepy in the first place? Momo’s face is obviously humanlike, but her bulging eyes and distorted mouth are distinctly nonhuman.

Our fear of faces like Momo’s might be explained scientifically. Fear is a difficult emotion to study; there’s debate about what fear even is. One obvious hypothesis is that humans and other animals respond to certain dangerous stimuli with fear and its associated behaviors in order to protect themselves. Our consistent reactions to things that seem to provoke fear and disgust can be explained in an evolutionary framework and have been important to our survival for a long time. And Momo can fit into several of them.

Fear of Disease

The avoidance of disease and parasites is a very important aspect of survival for all organisms, and humans are no exception. Disease can obviously threaten an individual’s survival as well as their success in reproducing. Many behaviors and physiological features in humans and other animals are better understood when viewed as fear reactions — either in avoiding disease or convincing others that we are disease-free. In support of this, a study of young people in Slovakia found that “disease-relevant” animals, like parasites, were more likely to cause fear and disgust than harmless “disease-irrelevant” animals.

Illness often causes outward symptoms, keeping us on the lookout for signs that those around us are infectious. We might subconsciously view Momo as someone who is sick — perhaps even as a corpse — that should be avoided.

Fear of Being Socially Outcast

As the average teenager can tell you, humans have an incredibly strong desire to fit in. To do this, we might spend a lifetime learning how to carry out elaborate social interactions, and at the times we are unable to perform these interactions properly, we can feel a sense of unease. This is especially true if we think the person we are faced with might turn aggressive. A study from 2012 describes how people often react more quickly to angry faces than happy faces, suggesting the possibility of a rapid fear response.

When we see her, we may immediately register Momo as human, but when we look closer, we see that her face is all wrong. This could mean we cannot determine her emotions or mood and, therefore, feel unable to engage in appropriate social interaction. Alternatively, perhaps Momo strikes us as a malevolent person who wants to harm us. Or, with her apparent wide-eyed surprise, she may appear to be a person experiencing fear herself, and we may or may not empathize with her.

Fear of Predators

Despite being apex predators ourselves, humans have been and sometimes still are subject to predation by other animals, and we haven’t forgotten how to respond to potential predators. In some cases, it’s the predator’s eyes that create the fear. Some animals, such as starlings, respond specifically to the eyes of predators, and butterflies are well-known for having eyespots that mimic a larger animal’s eyes to ward off others. At certain times, a fear of predation can even affect a group’s social dynamic, as with guppies that have more stable social ties when the risk of predation is greater. Besides merely driving animals to avoid harm, fear can enhance relationships.

Photo: Chandler Hilken/Unsplash

Maybe Momo’s round eyes with small pupils put us in mind of a large predator, like a lion, driving us to look away quickly. And possibly Momo has the effect of making us want to stick together, bonding over our shared fear. The different fear responses may depend on our proximity to danger and its intensity; presumably Momo, as a still image on the internet, provokes more passive responses.

The Science of Eeriness

Momo may also represent a specific type of fear-inducing stimulus that has attracted attention in recent years: the uncanny valley.

The uncanny valley is the idea that as nonhuman entities — such as robots and animation — approach a human-like appearance, they become more unsettling. The idea was described by roboticist Masahiro Mori in 1970. These entities are close to being human but are clearly “off,” though not far enough “off” to be obviously artificial. The things that fall in this “uncanny valley” can elicit fear or disgust in human viewers. Well-known examples include characters in the 2004 animation The Polar Express and CB2, the “child robot.”

Hypothesized emotional response of human subjects is plotted against anthropomorphism of a robot, following roboticist Masahiro Mori’s theory of the uncanny. The uncanny valley is the region of negative emotional response towards robots that seem “almost human.” Movement amplifies the emotional response. Graph by Smurrayinchster based on one by Masahiro More and Karl MacDorman via Wikimedia Commons/CC-BY-SA-3.0

Momo may fall firmly in the bottom of the uncanny valley. A study published in 2007 found that people respond negatively to almost-human faces but only when they contain abnormal features, such as oversized eyes. Momo certainly has those. Another study from 2011 found evidence that even babies can experience the uncanny valley effect from the age of 12 months. At about a year old, babies are adept enough at the finer points of human-face recognition to notice when things aren’t quite right. Monkeys also may experience it. In one study, macaques preferred to look at either real monkey faces or unrealistic monkey faces, compared with realistic but synthetic monkey faces.

Not all studies looking for the uncanny valley have found it, but this may be due to methodological differences. Perhaps the faces used in those studies just weren’t creepy enough. For example, an uncropped photo of Momo may seem distinctly less creepy because we can see her very nonhumanlike bird legs. More studies can help to narrow down exactly what triggers those eerie feelings.

There are a number of possible explanations for the uncanny valley. It may just be simple fear like the traditional responses described above. A similar possibility is that we are deciding that the object in question would not make a good mate. Other ideas are more philosophical — that uncanny objects are reminders of our own mortality or violate our sense of human identity. It may just be that we are aware that manmade objects should be less humanlike than an actual human, so their uncanny triggers — in Momo’s case, her exaggerated features — instead serve as a superstimulus for creepy feelings.


Whether the scary effect Momo has boils down to that we have basic and evolutionarily sensible fears or that we’re spooked by her firm existence in the uncanny valley, there’s another interesting thought. Does that knowledge make Momo more or less creepy?