Pollock’s Toy Museum is one of London’s loveliest small museums, a creaking Dickensian warren of wooden floors, low ceilings, threadbare carpets, and steep, winding stairs, housed in two connected townhouses. Its small rooms house a large, haphazard collection of antique and vintage toys – tin cars and trains; board games from the 1920s; figures of animals and people in wood, plastic, lead; paint-chipped and faintly dangerous-looking rocking horses; stuffed teddy bears from the early 20th century; even – purportedly – a 4,000 year old mouse fashioned from Nile clay.

And dolls. Dolls with “sleepy eyes”, with staring, glass eyes. Dolls with porcelain faces, with “true-to-life” painted ragdoll faces, with mops of real hair atop their heads, with no hair at all. One-hundred-and-fifty-year-old Victorian dolls, rare dolls with wax faces. Dolls with cheery countenances, dolls with stern expressions. Sweet dolls and vaguely sinister dolls. Skinny Dutch wooden dolls from the end of the 19th century, dolls in “traditional” Japanese or Chinese dress. One glassed-off nook of a room is crammed with porcelain-faced dolls in 19th-century clothing, sitting in vintage model carriages and propped up in wrought iron bedsteads, as if in a miniaturized, overcrowded Victorian orphanage.

Some visitors to the museum, however, can’t manage the doll room, which is the last room before the museum’s exit; instead, they trek all the way back to the museum’s entrance, rather than go through. “It just freaks them out,” says Ken Hoyt, who has worked at the museum for more than seven years. He says it’s usually adults, not children, who can’t handle the dolls. And it happens more often during the winter, when the sun goes down early and the rooms are a bit darker. “It’s like you’d think they’ve gone through a haunted house… It’s not a great way to end their visit to the Pollock’s Toy Museum,” he says, laughing, “because anything else that they would have seen that would have been charming and wonderful is totally gone now.”

A fear of dolls does have a proper name, pediophobia, classified under the broader fear of humanoid figures (automatonophobia) and related to pupaphobia, a fear of puppets. But most of the people made uncomfortable by the doll room at Pollock’s Toy Museum probably don’t suffer from pediophobia so much as an easy-to-laugh-off, often culturally reinforced, unease. “I think people just dismiss them, ‘Oh, I’m scared of dolls’, almost humorously – ‘I can’t look at those, I hate them,’ laughingly, jokingly. Most people come down laughing and saying, ‘I hated that last room, that was terrible,’” Hoyt says. Dolls – and it must be said, not all dolls – don’t really frighten people so much as they “creep” them out. And that is a different emotional state all together.

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Dolls have been a part of human play for thousands of years – in 2004, a 4,000-year-old stone doll was unearthed in an archeological dig on the Mediterranean island of Pantelleria; the British Museum has several examples of ancient Egyptian rag dolls, made of papyrus-stuffed linen. Over millennia, toy dolls crossed continents and social strata, were made from sticks and rags, porcelain and vinyl, and have been found in the hands of children everywhere. And by virtue of the fact that dolls are people in miniature, unanimated by their own emotions, it’s easy for a society to project whatever it wanted on to them: Just as much as they could be made out of anything, they could be made into anything.

“I think there is quite a tradition of using dolls to reflect cultural values and how we see children or who we wish them to be,” says Patricia Hogan, curator at The Strong National Museum of Play in Rochester, New York, and associate editor of the American Journal of Play. For example, she says, by the end of the 19th century, many parents no longer saw their children as unfinished adults, but rather regarded childhood as a time of innocence that ought to be protected. In turn, dolls’ faces took on a more cherubic, angelic look. Dolls also have an instructional function, often reinforcing gender norms and social behavior: Through the 18th and 19th century, dressing up dolls gave little girls the opportunity to learn to sew or knit; Hogan says girls also used to act out social interactions with their dolls, not only the classic tea parties, but also more complicated social rituals such as funerals as well. In the early 20th century, right around the time that women were increasingly leaving the home and entering the workplace, infant dolls became more popular, inducting young girls into a cult of maternal domesticity. In the second half of the 20th century, Barbie and her myriad career (and sartorial) options provided girls with alternative aspirations, while action figures offered boys a socially acceptable way to play with dolls. The recent glut of boy-crazy, bizarrely proportioned, hyper-consumerist girl dolls (think Bratz, Monster High) says something about both how society sees girls and how girls see themselves, although what is for another discussion.

So dolls, without meaning to, mean a lot. But one of the more relatively recent ways we relate to dolls is as strange objects of – and this is a totally scientific term – creepiness.

Research into why we think things are creepy and what potential use that might have is somewhat limited, but it does exist (“creepy”, in the modern sense of the word, has been around since the middle of the 19th century; its first appearance in The New York Times was in an 1877 reference to a story about a ghost). In 2013, Frank McAndrew, a psychologist at Knox College in Illinois, and Sara Koehnke, a graduate student, put out a small paper on their working hypothesis about what “creepiness” means; the paper was based on the results of a survey of more than 1,300 people investigating what “creeped” them out (collecting dolls was named as one of the creepiest hobbies).

Creepiness, McAndrew says, comes down to uncertainty. “You’re getting mixed messages. If something is clearly frightening, you scream, you run away. If something is disgusting, you know how to act,” he explains. “But if something is creepy… it might be dangerous but you’re not sure it is… there’s an ambivalence.” If someone is acting outside of accepted social norms – standing too close, or staring, say – we become suspicious of their intentions. But in the absence of real evidence of a threat, we wait and in the meantime, call them creepy. The upshot, McAndrew says, is that being in a state of “creeped out” makes you “hyper-vigilant”. “It really focuses your attention and helps you process any relevant information to help you decide whether there is something to be afraid of or not. I really think creepiness is where we respond in situations where we don’t know have enough information to respond, but we have enough to put us on our guard.”

Human survival over countless generations depended on the avoidance of threats; at the same time, humans thrived in groups. The creeped out response, McAndrew theorized, is shaped by the twin forces of being attuned to potential threats, and therefore out-of-the-ordinary behavior, and of being wary of rocking the social boat. “From an evolutionary perspective, people who responded with this creeped out response did better in the long run. People who didn’t might have ignored dangerous things, or they’re more likely to jump to the wrong conclusion too quickly and be socially ostracized,” he explains.

Dolls inhabit this area of uncertainty largely because they look human but we know they are not. Our brains are designed to read faces for important information about intentions, emotions and potential threats; indeed, we’re so primed to see faces and respond to them that we see them everywhere, in streaked windows and smears of Marmite, toast and banana peels, a phenomenon under the catchall term “pareidolia” (try not to see the faces in this I See Faces Instagram feed). However much we know that a doll is (likely) not a threat, seeing a face that looks human but isn’t unsettles our most basic human instincts.

“We shouldn’t be afraid of a little piece of plastic, but it’s sending out social signals,” says McAndrew, noting too that depending on the doll, these signals could just as easily trigger a positive response, such as protectiveness. “They look like people but aren’t people, so we don’t know how to respond to it, just like we don’t know how to respond when we don’t know whether there is a danger or not... the world in which we evolved how we process information, there weren’t things like dolls.”

Some researchers also believe that a level of mimicry of nonverbal cues, such as hand movements or body language, is fundamental to smooth human interaction. The key is that it has to be the right level of mimicry – too much or too little and we get creeped out. In a study published in Psychological Science in 2012, researchers from the University of Groningen in the Netherlands found that inappropriate nonverbal mimicry produced a physical response in the creeped out subject: They felt chills. Dolls don’t have the ability to mimic (although they do seem to have the ability to make eye contact), but because at least part some part of our brain is suspicious about whether this is a human or not, we may expect them to, further confusing things.

You can’t talk about creepy dolls without invoking the “uncanny valley”, the unsettling place where creepy dolls, like their robot cousins, and before them, the automatons, reside. The uncanny valley refers to the idea that human react favorably to humanoid figures until a point at which these figures become too human. At that point, the small differences between the human and the inhuman – maybe an awkward gait, an inability to use appropriate eye contact or speech patterns – become amplified to the point of discomfort, unease, disgust, and terror. The idea originated with Japanese roboticist Masahiro Mori’s 1970 essay anticipating the challenges robot-makers would face. Although the title of the paper, “Bukimi No Tani”, is actually more closely translated as “valley of eeriness”, the word “uncanny” hearkens back to a concept that psychiatrist Ernst Jentsch explored in 1906 and that Sigmund Freud described in a 1919 paper, “The Uncanny”. Though the two differed in their interpretations – Freud’s was, unsurprisingly, Freudian: the uncanny recalls our repressed fears and anti-social desires – the basic idea was that the familiar is somehow rendered strange, and that discomfort is rooted in uncertainty.

But the uncanny valley is, for scientists and psychologists alike, a woolly area. Given the resources being poured into robotics, there’s been more research into whether or not the uncanny valley is real, if it’s even a valley and not a cliff, and where exactly it resides. Thus far, results aren’t conclusive; some studies suggest that the uncanny valley doesn’t exist, some reinforce the notion that people are unsettled by inhuman objects that look and act too human. These studies are likely complicated by the fact that widespread exposure to more “natural” looking humanoid figures is on the rise through animated films and video games. Maybe like the Supreme Court standard for obscenity, we know uncanny, creepy humanoids when we see them?

But before the 18th and 19th centuries, dolls weren’t real enough to be threatening. Only when they began to look too human, did dolls start to become creepy, uncanny, and psychology began investigating.

“Doll manufacturers figured out how to better manipulate materials to make dolls look more lifelike or to develop mechanisms that make them appear to behave in ways that humans behave,” says Hogan, pointing to the “sleep eye” innovation in the early 1900s, where the doll would close her eyes when laid horizontal in exactly the way real children don’t (that would be too easy for parents). “I think that’s where the unease comes with dolls, they look like humans and in some ways move like humans and the more convincing they look or move or look like humans, the more uneasy we become.”

At Pollock’s, the dolls that people find particularly creepy are the ones that look more lifelike, says Hoyt; these are also the ones that have begun to decay in eerily inhuman ways. “The dolls don’t age well.… I think any time that a doll really tried to look like a human being and now is 100 years old, the hair is decaying, the eyes don’t work any more. So it looks as much like a baby as possible, but like an ancient baby,” Hoyt says.

Which presents an interesting phenomenon: The creepiness of realistic dolls is complicated by the fact that some people want dolls (and robots) that look as lifelike as possible. Reborns are a good illustration of the problem; hyper-realistic, these are custom-crafted infant dolls that, reborn artists and makers say, “you can love forever”. The more lifelike an infant doll is – and some of them even boast heartbeats, breathing motion, and cooing – the more desirable it is among reborn devotees, but equally, the more it seems to repulse the general public.

Perhaps it comes down to what we can make dolls into. In A.F. Robertson’s 2004 investigation into doll-collecting, Life Like Dolls: The Collector Doll Phenomenon and the Lives of the Women Who Love Them, some of the women who collected porcelain dolls thought of their dolls as alive, as sentient beings with feelings and emotions; these women who referred to their doll collections as “nurseries” were sometimes “shunned” by other antique doll collectors who did not have the relationship to their own dolls. Women – and it is almost exclusively women – who collect reborns often treat them as they would real babies; some psychologists have talked about “reborns” as “transition objects” for people dealing with loss or anxiety. Freud may have argued that all children wish their dolls could come to life, but even so, it’s not socially acceptable for adults to entertain the same desire. If we are creeped out by inanimate things that aren’t human looking too human, we may also be creeped out by adult humans pretending that these inanimate things are real.

“We’re creeped out by people who have these kinds of hobbies and occupations because right away, we jump to the conclusion, ‘What kind of person would willingly surround themselves with… humanlike things that are not human?’” says McAndrew, who also noted that he and Koehnke’s survey on creepiness found that most people think that creepy people don’t realize they’re creepy. “We’re on our guard to those types of people because they’re out of the ordinary.”

It’s also exactly the kind of thing easy to exploit in media. Some doll makers blame Hollywood films for the creepy doll stigma, and there’s no doubt that moviemakers have used dolls to great effect. But the doll was creepy well before Hollywood came calling. In the 18th and 19th centuries, as dolls became more realistic and as their brethren, the automata, performed more dexterous feats, artists and writers began exploring the horror of that almost immediately. The tales of German writer E.T.A Hoffman are widely seen as the beginning of the creepy automaton/doll genre; Jentsch and Freud used Hoffman’s “The Sandman,” as a case study in the uncanny. The story, published in 1816, involves a traumatized young man who discovers that the object of his affection is in fact a clever wind-up doll, the work of a sinister alchemist who may or may not have murdered the young man’s father; it drives him mad. The horror in this story turned on the deceptive attractiveness of the girl, rather than any innate murderousness in her; for the 19th century, creepy dolls stories tended to be about the malevolence of the maker than the doll itself.

In the 20th century, creepy dolls became more actively homicidal, as motion picture technology transformed the safely inanimate into the dangerously animate. Some evil dolls still had an evil human behind them: Dracula director Tod Browning’s 1936 The Devil-Doll featured Lionel Barrymore as man wrongly convicted of murder who turns two living humans into doll-sized assassins to wreak his revenge on the men who framed him. But then there was The Twilight Zone’s murderous Talky Tina, inspired by one of the most popular and influential dolls of the 20th century, Chatty Cathy – “My name is Talky Tina and you’d better be nice to me!”; the evil clown doll from Poltergeist, cannily marrying two creepy memes for maximum terror; and of course, Chucky, the My Buddy clone possessed by the soul of a serial killer in the Child’s Play series. The 1980s and 1990s saw dozens of B-movie variations on the homicidal doll theme: Dolly Dearest, Demonic Toys, Blood Dolls. In 2005, the evil denizens of the Doll Graveyard came back for teenaged souls (and eyeballs, it appears); in 2007, homicidal ventriloquist dummies were going around ripping people’s tongues out in Dead Silence.

Most recently, devil worshippers inadvertently turned a smiling vintage doll into a grinning demon in last October’s Annabelle, a film in the Conjuring franchise. Director John Leonetti, who did not return requests for comment, told The Huffington Post that dolls made exceptional vehicles for horror films. “If you think about them, most dolls are emulating a human figure,” said Leonetti. “But they’re missing one big thing, which is emotion. So they’re shells. It’s a natural psychological and justifiable vehicle for demons to take it over. If you look at a doll in its eyes, it just stares. That’s creepy. They’re hollow inside. That space needs to be filled.” With evil.

But the story of Annabelle the demonic doll, however, becomes far creepier – and more titillating – when it’s accompanied by the claim that it’s “based on a true story”. Paranormal investigators Ed and Lorraine Warren claimed that Annabelle the Raggedy Ann doll, whose original owners frequently found her in places they hadn’t left her, was being used by a demonic spirit in its quest to possess a human soul; she now lives in a specially-made demon-proof case marked “Warning: Positively Do Not Open” at the Warren’s Occult Museum in Connecticut. Annabelle is not the only evil doll the museum alleges it houses, and there are many more such purportedly real-life possessed dolls around the world; as NPR reported in March, “Haunted dolls are a thing”. Robert the Doll, the lifelong companion of an eccentric Key West artist, glowers at people from the East Martello Museum, where he’s become a tiny, haunted cottage industry unto himself; you can even buy your own replica Robert doll to blame things on. If you are unable to visit a haunted or possessed doll in the flesh (or porcelain, as the case may be), then you can always watch a live feed of this rural Pennsylvania family’s haunted doll collection. These stories, like the stories of real live clowns who murdered, feed into a narrative that makes dolls scary.

Annabelle (2014) John has found the perfect gift for his wife, Mia: a beautiful, rare vintage doll. But Mia's delight with Annabelle the doll doesn't last long. Buy

It doesn’t appear that the creepy stigma increasingly attached to dolls, nor the bevy of scary doll films, has done anything to really harm sales of dolls in the US. While sales of dolls in 2014 were lower than they had been 10 years earlier, the figures were still in the billions of dollars – $2.32 billion to be exact, outstripping sales of vehicular toys, action figures, arts and crafts, and plush toys, and second only to outdoors and sports toys sales. it hasn’t put a damper on the secondhand and collectible doll market, where handmade porcelain dolls regularly fetch in the thousands of dollars. In September 2014, a rare Kämmer & Reinhardt doll from the early 1900s was auctioned off for an unbelievable £242,500 ($395,750); the report suggested the buyer not see Annabelle, which was due to be released soon after.

The creepiness of dolls sometimes adds to their appeal; some doll makers are actively courting creepy, such as this reborn artist who sells “monster” babies alongside regular babies, or the popular and scary Living Dead Dolls line. Because the fact is, people like creepy. The same mechanism that makes us hyper-vigilant also keeps us interested: “We’re fascinated and enthralled and little on edge because we don’t know what comes next, but we’re not in any way paralyzed by it,” muses Hogan. “We’re more drawn into it, which I think it’s that drawing in or almost being the under spell of wanting to find out what comes next is what good storytellers exploit.”

And, maybe, good doll makers, too?