Dolly mixture: Kevin Pender in Arnotts' mannequin room in Dublin

The room is small and dimly lit, with a bare concrete floor. It is reached through security doors and the length of a deep corridor negotiated in pitch darkness. ("Recession," explains one workman briefly as we pass.) Inside, the scene is a little unnerving. Ranks of human figures stand all around, stilled in mid-gesture, or as if about to take a step, though one or two have toppled over. In one corner lies a cardboard box of limbs. "It's kind of like a mannequin version of Saw," observes my companion cheerily, as he steps over a crumpled heap of babies.


Kevin Pender is the design director of Arnotts department store in Dublin city centre, and takes charge of all their mannequins for display, outside and in. The room we're in, deep in the guts of the old Irish Independent building at Abbey Street, is the mannequin store. He knows the stock of figures intimately, their origins and manufacturers. "These are Rootstein, these are Schlappi. These are Pucci," he says.


Arnotts is a 300,000-square-foot shop with about 35 windows, all them populated by dummies, almost all the time. Managing them is literally a full-time job.


Mannequins have been around almost as long as the clothes they're used to show off. When archaeologists broke into Tutankhamun's tomb, next to the king's robes they found a dummy made to his measurements, dating from 1350 BC. But shop figures really came into their own in the last century or so, when new technologies allowed the manufacture of cheap, portable models to show garments in window displays. (Some of the first attempts were made of wax, which had an unfortunate tendency to melt in warm weather, leading the bodies to slump and mouths to droop open as if they had been quietly murdered in their positions.) Now, almost no clothing is sold without them.


The window-dresser's job, explains Pender, is to "connect" with people outside.


"You have to captivate, and you have a very short period of time to do that – it could be five, ten seconds. To reach that person in some way so that they make the decision to come into your store."


Mannequins are everywhere, on every street in every town, because they're the best way of doing that. This is partly because clothes look better on figures than they do on the shelf, but it's also because people respond more strongly to other people – even plastic versions of other people – than they do to anything else.


"They're just a fantastic selling tool," says Pender. "And because of their different poses, it allows you to put together scenarios, or interactions between them – to make them characters in a little story that passers-by can relate to. They allow us to make that emotional connection. We've had speech bubbles with them; we've added thought bubbles."


So his job is to give the mannequins personalities? "I've given them names," he says.


These days, mannequins come in all shapes and sizes, but some of the most realistic are made by a firm called Rootstein. Adel Rootstein more or less invented the mannequin as we know it. Before her, in the 1940s and '50s, window dummies looked unglamorous, more or less like everyday people. They were shorter and comparatively dumpy. Male figures sometimes had a hole drilled in their mouths so they could smoke a pipe.


Then, in 1964, Adel commissioned a sculptor to make a mannequin from the body of the 14-year-old model Twiggy. Impossibly tall and thin, unsmiling, the figure wasn't what normal people looked like, it was what they wanted to look like – not that they ever would. It was a sensation, and launched the firm to global success.


Today, Rootstein still makes its mannequins from real-life models and supermodels, under the control of creative director Kevin Arpino. He selects the girls and boys who will be rendered in fibreglass.


"They work with our sculptors for two hours a day, for three to four weeks," he says.


The sculptors produce a life-size figure in clay, to which hands are added with casts of the model's real hands. Then the sculpture is turned into a mould from which thousands of dummies, with detachable fittings, can be produced.


Rootstein's goal has always been to produce perfection in human form – or whatever fashion currently holds up as perfection.


"We do the person as they are, but we also do a slightly stylised version," Arpino says. "What would be a beauty spot in real life is an imperfection in a mannequin. So we have to tweak things. We Photoshop a person. That's a good way of putting it."


Wrinkles, cellulite, moles, all the hallmarks of biology are erased – or "refined", as Arpino puts it – away. After all, at their most basic level, mannequins are just human-shaped sales racks for clothes. Back in the storeroom, Kevin Pender takes one girl by the hand.


"All the hands screw off," he says, demonstrating. "And then the arms actually pop on and off" – with a sharp twist and an alarming 'clack', he relieves the model of her gracefully-shaped limb – "like that. Because you have to be able to dress them."


Mannequins don't bend, except for the baby ones, which are basically just articulated bags of stuffing. "Bendies, as we call them," says Pender.


I notice that several bald figures have Velcro strips across their scalps. "That's an old trick really," he says. "Just to make sure you keep the wigs on. You can send them off to be styled." To a wig hairdresser? "Yeah." When I mention some dummies I've seen with moulded plastic hairpieces that screw into the head, he smiles tolerantly and says, "They'd be relatively cheap. Probably Japanese."


Rootstein's figures are not relatively cheap, clocking in at around €900 apiece. But for that, you might get a supermodel. The company records are a lesson in fashion history, moving from casts of power-dressing Joan Collins in the 1980s and 'anorexia chic' Jodie Kidd in the '90s to Erin O'Connor and Agyness Deyn today. But not every model works in fibreglass, Arpino says.


"Sometimes a girl comes in and she's gorgeous, but she doesn't make a good mannequin. Pretty people" – people with soft, small features – "don't really come over as a mannequin. We tend to use quite hard faces, somebody with a strong nose or a strong mouth. And also someone who can be a chameleon, because customers can dictate what skin colour they are, what hair they have, what makeup. So you try and do a face that's like a blank canvas."


Is that why mannequins always look so serious? "We have done laughing ones, and smiling ones and pouting ones," muses Arpino, "but people don't like them really. People don't like teeth on mannequins, I don't know why. They don't sell," he says. "But what you really don't want is a sad mannequin."


And what about eyes? "We paint the eyes," he says. "And we always paint the eyes looking slightly to the left or the right. Because if you paint them straight ahead, you get that portrait-on-the-wall syndrome where they follow you round the shop. So you avoid that. You don't want to freak out the customers."


This is a legitimate worry for mannequin makers. The fear of mannequins is called 'pediophobia', and the figures have long had a slightly ghoulish image in popular culture. (In The Silence Of The Lambs, dismembered dummies are found among Hannibal Lecter's possessions.) This bad press is sometime helped along by real titbits, such as the fact that when Michael Jackson was on trial on sexual abuse charges, it emerged he had installed life-size child mannequins at his Neverland ranch, including one dressed in a Boy Scout uniform. Judi Henderson, who manages a firm called Mannequin Madness, sees this negative reaction a lot.


"When people come into our warehouse for the first time, they are sometimes a little taken aback," she says. "We sometimes have mannequins that are in the process of being dismembered. When you see a row of legs, or a box full of hands, that can be a little unnerving. But they're just giant Barbie dolls to me."


She too likes to make a personal connection with her figures. "All of our mannequins have names. They definitely have a little personality to them."


Her company, based in Oakland, California, is in the business of recycling. The life of a shop dummy, she explains, is short and sharp.


"Major stores tend to hold on to their mannequins for maybe five years," she says. "After that, the style changes. So for a couple of seasons, headless mannequins are popular, then the mannequins that have kind of an egghead look are popular. They have to be very sensitive to trends."


Obsolete figures are usually disposed of in the mass grave of a skip. But her firm takes them and sells them on to smaller shops, or home businesses. A mannequin's life is one of decline: you start at the top of the retail food chain and work your way down.


She also tends to injured figures. "We have a repair facility. Most of the time it tends to be things like broken or missing fingers, because the hands get the most wear in the shop. Then there's the equivalent of mannequin osteoporosis, like, say, a crack on the butt or on the hip. Or we had a case where a mannequin was completely decapitated."


The company patches up cracked fibreglass, moulds new heads and fingers, and retouches wigs and makeup.


"The wigs can be very expensive. Like, hundreds of dollars, for human hair wigs with a really fancy hairstyle."


And it's not just businesses that are paying. "I have people who collect mannequins," she says. "People like mannequins, or like to dress them up, like somebody else might collect postage stamps. I'm talking about private individuals, a large majority of whom are gay men. One guy bought an Elton John jacket at an auction, so he wanted a little mannequin form, so he could display the jacket in his dining room."


Rootstein figures are especially popular with these connoisseurs, she says.


"Mannequins are like cars, and Rootstein are like the Mercedes-Benz or the Rolls-Royce. And certain models even within the Rootstein line – a seated or reclining mannequin has a lot more cachet than one that's standing."


This is part rarity value, and part practicality. "It's easier for someone to put a mannequin, let's say, lying down on their baby grand piano, or on top of a dresser, than just standing up."


People have strange ideas about mannequins. Pender tells me that Arnotts still gets complaints from shocked passers-by when they forget to put the blinds down while undressing the dummies. And this is despite the fact that, like Barbie and Ken, the figures' private parts are nothing but a discreet curve.


"On the boys, they've got to have a bulge to fill out a swimsuit," Kevin Arpino tells me. "On the women, we don't put anything 'intricate' in, as they say." He pauses. "We do their tits, obviously."


Until the 1960s, it was illegal in several US cities to undress a mannequin in public. After all, mannequins are designed to be desirable, or what society deems desirable.


"In all the years I've been doing this," Judi Henderson says, "I can count the number of mannequins I've had that look like an older person on maybe three fingers. And then when I have a plus-size mannequin – even though plus-size in mannequin terms is really about normal size for a woman – those are such slow movers for us. It's all about a fantasy. People don't want reality."


To one side of the storeroom, Kevin Pender shows me some dummies that are chipped and cracked, propped carelessly in a corner until they can be made faultless again. In the world of mannequins, the point is to appear real while projecting a fantasy – a remote, unattainable ideal.


"It's a weird and wonderful place," he says as we leave. And he turns out the lights, plunging the crowd of perfect, silent figures back into darkness.