This cultural vista - endless shallow stories, endlessly recycled and targeted by shrewd adults at young children - has long made some commentators nervous. Two weeks ago the New Yorker published a despairing article by David Denby, a father rendered eloquently furious by the "avalanche of crud" that he feared had "buried alive" his children. American films and television and their waves of toy-shop spin-offs had become, he argued, "not just a piece of reality ... but the very ground of reality" for his sons. They talked in screen voices, copied its language, its gestures, and above all its attitudes: "They become ironists - ironists of waste. They know that everything in the media is disposable. Everything on television is just for the moment - it's just television - and the kids pick up this devaluing tone, the sense that nothing matters."
Denby's polemic was predictably well received. But in its rush to condemn the entertainment corporations, it concealed an argument rather more interesting than it revealed. Early on, Denby admitted he had played his sons' electronic games and watched their movies himself: "This is part of the confusion. How can you fight what you enjoy yourself?" Yet he never considered whether hours blasting through Warcraft and Doom had corrupted him too. Nor did he explain why he found "endlessly repeated pleasure" in The Empire Strikes Back.
Could it be that Denby, far from being separated from his sons by popular culture, is himself squashed under the same weight? Rather than worrying about the effects of adult culture on children, perhaps he should be worrying about the effects of child culture on adults.
Once, there were rough differences between adults and children: adults worked, made plans, interacted with other people; children played, changed their minds, thought about themselves. Now, it's not so clear. Childhood has become a perpetual state; increasingly, childish things are not put away. More and more young adults live at home with mother. Bankers watch The Big Breakfast before work, with its grinning children's television presenters and giddy nursery games. Postgraduates spend afternoons on the Internet, exploring wide-eyed or throwing anonymous, delicious tantrums. Parents spend weekends at the shopping centre, rushing between novelties, wanting and discarding with the fickleness of five-year-olds.
The market wants adults to become children. It makes them more faddish consumers, more flexible workers, more unquestioning - even welcoming - of the constant changes it imposes. Infants don't think to form trade unions.
No part of the market has done more to infantilise than Denby's enemy, the American entertainment industry. Over the last two decades, it has learnt a lesson from Disney: get the grown-ups too. In Hollywood, this process began in the late Seventies with the blockbuster. Studios stopped making challenging films like Taxi Driver, with their audience-splitting realism and awkward, pessimistic politics, and turned to producing benign, other-worldly epics with cartoon morals which would attract whole families. Star Wars was the template: in 1977 those families made it the most profitable film ever.
More quietly, television made the same discovery. Nickelodeon was set up in 1979 as an American cable channel specifically for children. It showed cartoons and soap operas all day, every day in a giggling adult- free blur. Then the marketing department discovered that students were watching too, in particular a frenzied cartoon about a cat and a chihuahua called Ren & Stimpy. Nickelodeon rushed to arrange Ren & Stimpy nights in halls of residence. Nowadays, one viewer in seven of the cartoon is an adult; Nickelodeon is expanding into Malaysia and Brazil.
In Britain, Nickelodeon is on Sky and Ren & Stimpy are on BBC2 as well, broadcast long after children have gone to bed. And our programme-makers have learnt to follow the Americans. When Channel 4 wanted a new breakfast programme in 1992, to replace its earnest Channel 4 Daily, a new production company called Planet 24 had the answer: children's television. The Big Breakfast took its speed and stunts and camera-grabbing style straight from Seventies kids' shows like Tiswas and Swap Shop. Its young adult audience wanted to watch them again, and ratings climbed. When Keith Chegwin arrived as a presenter, well into his thirties but still smiling his Swap Shop smile, they rose even further. Chris Evans launched a substantial career by leaping about.
The Big Breakfast seems entirely without guile. It is not. Last Friday, on the 1,001st show, Chegwin introduced an item about a new film. "There's only one way to describe Independence Day," a voiceover boomed as spaceships exploded and the official trailer ran, "awesome." The camera cut back to Chegwin in the studio: "It's the first time on The Big Breakfast," he said, "that people have been really glued to that monitor over there." His co-presenter had something to add: "It's going to be awesome."
Yet we still watch. Robert Bly, an American author and polemicist for the men's movement, thinks he knows why. "Adults regress towards adolescence and adolescents, seeing that, have no desire to become adults," he writes in The Sibling Society, to be published in Britain in January. "Half- adults" result: grown-ups living through a perpetual present of self-gratification, narcissistic about their own generation but cut off from everyone else.
Bly blames the decline of the family and of deference to such traditional centres of authority - the loss of what he calls "the vertical gaze". In Britain, his conservative view finds a surprising ally. Mark Simpson, a gay critic of old-fashioned masculinity, says: "The family used to be one of the institutions that demanded people grew up ... be responsible for another life, be stoic, self-sacrificing. Now adults view life in terms of 'What do I get for Christmas?', rather than 'What do I do with my life before Christmas?' "
Ray Pahl, a professor of sociology at the University of Essex, is less censorious. "Adult institutions are seen as a sham. In the workplace adults are treated in such a way that they cannot behave as they did in the past. They live for today because tomorrow they will get the sack." Even when jobs are secure, their demands are so great and exhausting that they leave no time for growing up. Pahl has studied a group of graduates from an Oxford college who all left to work in the City in the Eighties. Years into their careers, he found, they were still taking their washing home to their mothers.
Such behaviour seems rather pathetic; it could also be a form of realism. As the market outflanks handed-down ways of understanding the world, it may be an advantage to be childishly unformed and unencumbered by responsibilities. Having a life is additional hard work, a luxury.
This new immature species is most obviously present in American computer companies, perhaps the next makers of global culture after the entertainment conglomerates. In Silicon Valley and Seattle programmers live enclosed in corporate wombs, with drip-feeds of free caffeine, the latest hardware and huge salaries. In return, their employers colonise their lives, demanding endless hours of "play" and organising what little leisure time remains into company activities. Consequently, programmers may be millionaires but, in their late twenties, still live in shared houses. Adult decisions and compromises are endlessly deferred.
Yet living as a permanent child is not enough. There is always another generation coming up behind: children themselves. A month after Robert Bly's book is published, a younger writer called Douglas Rushkoff will present a rather different view of the age of the child. Playing The Future is subtitled How Kid Culture Can Teach Us To Thrive In An Age Of Chaos. Rushkoff argues that "screenagers", children who have used computers since infancy, will have effortless advantages over their elders in processing information when they reach the job market. No amount of time in the multiplex will save us.