Tom Cruise walks past a line of moving, talking ads as he is courted by Guinness and Lexus to buy their pints and cars. They know his name and all his particulars because their ads are triggered by iris-scanning. According to the group of US experts who acted as advisers to Steven Spielberg's latest film, this is what advertising will be like in 2054.

In Minority Report, Spielberg has created a world where, thanks to a unit of psychics run by "pre-crime detective" John Anderton (Cruise), murder is prevented before it happens. The movie is not only an exploration of the potential of precognition, but a glimpse of how a consumer-based society - in this case Washington DC - might function in 50 years' time; a place where advertising and branding play an important role.

And it's not entirely fiction. During pre-production, the film's crew got together a thinktank of what they called "futurists" - specialists in computing, transport and the environment, plus staff from Wired magazine and Douglas Coupland, author of Generation X. In a two-day brainstorming session in April 1999, the group came up with ideas on how the US might look and function in 2054.

One of their premises was that the public would be willing to give up a lot of personal information in return for a crime-free society. The boon to advertisers is obvious: people's identities become public property, and advertising is highly targeted at individuals. Add to that some hi-tech concepts and a lot of computer wizardry and the film becomes an adfest, a world where every surface is a billboard and every sell is precise. The iris-scanning that sets ads in motion is as all-pervasive in Spielberg's world as security scanners in shop doorways are today.

We see digitally imaged 3D ads wrapped around the sides of buildings. Cars carry advertising inside and out (while driving, Cruise's character is shown images on a screen of dream beaches, enticing him on a holiday to Hawaii.) When he pours breakfast cereal from a box, the package plays a jingle. On the run after the psychics have a vision of him killing someone, Anderton carries a newspaper whose images and headlines move as he looks at them.

Some of the ideas are not a huge stretch of the imagination. Anyone who surfs the net is subject to pop-up ads and targeted messages. And in the US, some brands are paying people to drive cars with their logos on and "wrapped" with their ads. And this, says Alex McDowell, the film's production designer, was the intention - to come up with concepts that would be novel yet believable. "Steven really wanted the audience to feel the familiarity of all of these things. He didn't want to make a sci-fi movie but a future reality movie."

McDowell says an "unprecedented" amount of work went into researching the world of Minority Report, which is based on a short story by sci-fi author Philip K Dick. The producers even hired an advertising agency, 3 Ring Circus, to make the ads that appear in the film.

"We had a blast," says Anne White, the agency's former executive producer and now managing director of TAG, a creative branding company in Los Angeles. The agency worked on some of the ideas put forward by the think tank, and the storyboards were sent to the product placement brands appearing in the film - among them Guinness, American Express, Aquafina, Reebok, Pepsi and Bvlgari.

But whereas these corporate sponsors would usually see a clip of the film and OK it, there was no such agreement with Minority Report. Advertisers were shown storyboards but no clips, and ultimately Spielberg and the film's distributors, 20th Century Fox, had the say on how the brands appeared. Not only that, the sponsors' normal ad agencies were left powerless and sometimes frustrated by their lack of input. "It was a huge leap of faith," says White. "But the reactions were pretty unanimous - everyone liked the concepts."

What they didn't bank on was that during the time it took to make the film, some of their ideas were starting to happen. "We looked at the use of holographic-type billboards that give a 3-D effect. Then about nine months ago in LA I saw an ad for a car where, as you walked past it, the car disappeared," says White.

Identification by iris-scanning is already used in airports, including Heathrow. So, in theory, all the technological components are there to take iris-scanning into the realm of advertising. But there are a few hitches. "What the technology can't do currently is reliably identify someone from a distance," says Mike Thieme, senior consultant with the International Biometric Group in New York, which helps prisons and employers install biometric scanners that read faces, irises and fingers for security purposes. Face recognition can happen at up to 20 feet, he says, but for successful iris-scanning the subject has to be within three feet of the scanner. They also need to be cooperative, looking at a camera with the intention of being recognised.

Thieme is sceptical about whether people would want in-your-face advertising as happens in Minority Report. "The idea of walking down the street and being pulled out of a crowd and having advertising pointed at you, right now that would be seen as highly invasive."

John Underkoffler, one of the "futurists" and a science and technology consultant on the film, acknowledges the difficulties. The use of iris-scanning to advertise is possibly further off than 3D billboards, he says. "There are myriad problems with that kind of identification - for example if the person is blinking at the time, or turned away."

But he says some of his colleagues at the Massachusetts Institute of Technology - where production designer McDowell first met Underkoffler during research for the film - have been testing the idea of electronic, self-reprinting paper, as used by the futuristic newspaper in the film.

"We were suggesting [in the film] that any surface would be capable of display, and almost anything is fair game for advertising," says Underkoffler. But he is worried by the civil liberty implications of personal information becoming public property. "It's not something that's easy to stop. That kind of advertising will ride along with advances in biometrics. And why wouldn't the FBI want to make a quick few bucks selling people's identities to Guinness or Lexus?"

Moreover, with security such a hot issue, Underkoffler thinks the American public have become less likely to resist such developments. "I think we are at a tipping point. With the awful events of last September there's all sorts of legislation that will further erode civil liberties and people don't seem to be paying much attention. People are a little more willing to give away their freedom."

But media experts agree that being able to work with that sort of information and develop such highly targeted commercials is an advertiser's wet dream. "Everyone wants to get directly to their audience," says White. "Why waste your money on people that aren't interested in what you're selling? When the advertiser knows you, some people are going to like it and some are going to hate it. Yes, there's the scary Big Brother thing. But I personally don't want to have to watch adverts for incontinency pads, at least until I'm ready for them."