Rihanna's sexy, provocative duet with a French supermodel has shocked some. But, as Polly Vernon finds, they are only the latest in a line of female pop stars - Lady Gaga, Beyonce, Katy Perry - resolutely in control of their own sexual imagery.

The video that accompanies Te Amo, the latest song from R&B megastar Rihanna, is in many respects an unremarkable effort. It's rammed with your standard pop shorthand for decadent, intense, dangerous-yet-picturesque passion.

Scene one: a mindlessly sexy love interest drives a vintage car up the gravelled path of a grand and ghostly house. Rihanna waits within, clad only in a leotard, lace gloves and ankle boots. She writhes around a bit in frenzied anticipation. Scene two: love interest enters the room in which Rihanna writhes and approaches the singer - slinkily and with purpose. They dance together erotically, never quite touching. Scene three: the couple cavort in silhouette; Rihanna plays the dominatrix, sings the song's chorus into her lover's ear, drags a dark-painted fingernail along the length of her lover's jaw. So far, so predictable - apart from the fact that Rihanna's love interest is played by Laetitia Casta, a 32-year-old French supermodel turned actress.

"Then she said 'te amo', then she put her hand around my waist ... "I said 'te amo, wish somebody'd tell me what she said', Don't it mean 'I love you'?"' run the lyrics, which Rihanna sings over a loaded, sinister and sexy beat. YouTube was registering 9,125,000 previous views by the time I got to it - and, well, you can quite imagine why.

The winter of 2010 has been monopolised by videos just like this. Glossily hedonistic, hyper-sexualised, controversy- embracing, arch and incorporating at least one visual reference to sado- masochism. Furthermore, they've all been the work of extremely high-profile female artists.

In June, Katy Perry shot streams of whipped cream from a red sequin bra and gyrated on a candyfloss cloud for her number one song, California Gurls [sic]. A week later, Beyonce wore a basque, flexed a whip, smoked a fag and subverted the cliched ideal of the compliant 1950s housewife in the video for Why Don't You Love Me? In July, Christina Aguilera wore designer fetish gear and reprised the pseudo-sapphic theme with one of her dancers in the video for Not Myself Tonight. And that's just for starters.

Of course, pop music has always been sexually charged: that's half its point. Pop videos have always reflected this, ramping up the sexual aspect of songs: that's their entire point. But still, what we are witnessing here is a very specific set of visuals and notions, which encompass a series of recurring themes (lesbianism, whips, retro-hairstyles and extremely high-end fashion), and which mark a shift in culture.

Where did it come from? Lady Gaga, obviously. That unrelenting, ubiquitous, all-singing, all-piano-playing, unapologetic, bleached blond spectacular of a pop concept. Gaga (as she's popularly known) only entered the public consciousness 18 months ago when she released her first single, Just Dance, but she has come to inform and alter it profoundly. Those videos, those themes, that subversive sexiness, is very much her shtick.

Not everyone thinks her reach is a good thing, mind. "Gaga has launched every single woman in pop music into this crazy personality crisis," the male pop star Mika announced, sniffily. "I don't think men have felt it, I think it's a female thing. I'm looking forward to seeing what else is out there." This, a week after British record producer Mike Stock (previously of Stock, Aitken and Waterman) pronounced contemporary music videos "99 per cent R 'n' B, 99 per cent of which is soft pornography".

"You can't watch a Lady Gaga video with a 2-year-old," he added.

Which you probably can't. But that doesn't mean that we aren't a lot better off for her, or that her videos aren't important. To dismiss Lady Gaga - and her visual spawn - as salaciously, gratuitously, unnecessarily sexual, is to miss the point. To denounce it as yet another facet of our increasingly porn-obsessed, casually misogynistic culture is just plain wrong.

The full force of Lady Gaga's new sexual aesthetic was unleashed in March, with the video for her song Telephone. Telephone is nine minutes, 32 seconds worth of camp joy. It's a mini film, in which Lady Gaga gets sent to prison, flirts with female inmates (while wearing a studded leather bikini and sunglasses fashioned from lit cigarettes), gets released into the care of co-star Beyonce ("You've been a bad girl, Gaga") and whizzes off on a cross-country killing spree. Telephone is funny, lush, nuanced, clever. It makes a knowing virtue of blatant product placement and of referencing everything from the 1974 film Caged Heat, to Shania Twain's video for That Don't Impress Me Much, to Pulp Fiction and Thelma & Louise.

But it's the sexual undertones of the piece, the suggestion of a relationship between the fictionalised Beyonce and the fictionalised Gaga, that really mark out Telephone. It crackles with naughtiness. It's genuinely shocking to see the formerly very mainstream and very heterosexual Beyonce so complicit in Lady Gaga's transgressive vision.

Lady Gaga built on the Telephone moment by posing for the cover of the April issue of Britain's Q magazine, clad in studded skin-tight trousers and pointy fingered leather gloves, with a dildo strapped to her crotch. In June she released her single Alejandro; in the video she played further with ideas of sexual identity and dominance, toying with the pale bodies and unknowable affections of legions of androgynous male dancers. (She also incorporated a series of homages to Madonna's finest visual moments within the mix.)

So no, Mike Stock, you wouldn't necessarily want to watch Lady Gaga videos, or leaf through her media coverage, in the company of a 2-year-old (although heaven knows how much of Lady Gaga's most risque imagery would resonate with your average pre-schooler). I wouldn't want to watch it with a 13-year-old either. But I really wouldn't mind if that 13-year-old was watching it behind my back.

Gaga's video version of sexuality is extraordinary. It's extraordinary from an aesthetic perspective. She makes fashion statements out of gimp masks and gaffer tape, and orgies of vast synchronised dance segments. She turns sex into extremely camp theatre and the end result is challenging and alarming and powerful and exciting. If it wasn't, it wouldn't have been revisited by so many other singers.

But it's also extraordinary from a political perspective. Lady Gaga presents an extremely empowered vision of sex and sexiness. Hers is a million miles away from the cynical, soulless titillation of your average Britney Spears video, of ... Baby, One More Time, for example (in which Spears, who was 17 at the time, dressed as a 14-year-old schoolgirl and beseeched whoever to "hit me baby, one more time").

It's the opposite of the sex offered us in the majority of R&B and hip-hop videos, in which unnamed, interchangeable bikini-clad models dance for the slathering delectation of the male recording artists. Because men dance for Lady Gaga.

Gaga owns this version of sex and she's not asking you to approve it. She's a complete pop icon - but she's no pin-up.

She hasn't bothered constructing a version of herself designed to please a straight male audience. Lady Gaga doesn't do pretty, or available, or submissive, or obviously glamorous. Instead she does scary, she does theatrical, she does brave. Her costume choices - though often revealing, and sometimes not entirely complete; she famously chose to go on stage at the Glastonbury festival in Britain in 2009 without any pants - are too fiercely directional to appeal to most men.

There is something Bowie, something early Madonna-esque about the way Lady Gaga wields her sexuality. Something unapologetic, unflinching, and shameless in the very best sense.

Furthermore, I know I'd much rather see Rihanna cavorting with Casta than I would watch her sing the bitter chorus on Eminem's Love The Way You Lie, an uncomfortable paean to a relationship defined by domestic abuse (number one at the time of writing). The more Lady Gaga-referencing works in circulation, the better.

- OBSERVER