Americans are swimming in a sea of messages.

Each year, legions of ad people, copywriters, market researchers, pollsters, consultants, and even linguists—most of whom work for one of six giant companies—spend billions of dollars and millions of man-hours trying to determine how to persuade consumers what to buy, whom to trust, and what to think. Increasingly, these techniques are migrating to the high-stakes arena of politics, shaping policy and influencing how Americans choose their leaders.

In "The Persuaders," FRONTLINE explores how the cultures of marketing and advertising have come to influence not only what Americans buy, but also how they view themselves and the world around them. The 90-minute documentary draws on a range of experts and observers of the advertising/marketing world, to examine how, in the words of one on-camera commentator, "the principal of democracy yields to the practice of demography," as highly customized messages are delivered to a smaller segment of the market.

Take the 2004 presidential sweepstakes for example. Both the Republicans and the Democrats were prepared to go to extraordinary lengths to custom craft their messages. "What politicians do is tailor their message to each demographic group," says Peter Swire, professor of law at Ohio State University and an expert on Internet policy. "That means…Americans will live in different virtual universes. What's wrong with living in different universes? You never confront the other side. You don't have to deal with the uncomfortable facts that go against your worldview….It hardens the partisanship that's been such a feature of recent American politics."

FRONTLINE analyzes the 2004 campaign where, for the first time, the latest techniques in narrowcasting were put into effect. The antithesis of traditional broadcasting, narrowcasting involves crafting and delivering tailored messages to individual voters based on their demographic profiles.

Political marketers are just now discovering new ways to use the techniques that have long been employed by the private sector. FRONTLINE visits Acxiom, the largest data mining company in the world, where vast farms of computers hold detailed information about nearly every adult in America. Data mining, a practice that predicts likely behavior based on factors such as age, income, and shopping habits, has been the gold standard of commercial advertisers. Acxiom promises its clients a better way to target their messages to individual consumers.

"There is an age-old anxiety among advertisers that they are wasting their money, that they cannot know whom they are reaching and with what impact," says Rushkoff, who collaborated with Dretzin and Goodman on FRONTLINE's "The Merchants of Cool," which examined the process by which corporate conglomerates have co-opted teen culture in order to capture the multibillion-dollar adolescent market.

But Rushkoff predicts, "Anxiety is giving way to a confidence that they will soon have access to the core emotional needs of nearly every American shopper and voter."

There is, however, a paradox. While the techniques of the persuaders have become more sophisticated, consumers have never been more resistant to marketing messages. Yet today, advertisements fill up nearly every available inch of the landscape.

"You cannot walk down the street without being bombarded," advertising writer Bob Garfield says. "You go to fill your gas tank and you look at the pump and you're seeing news headlines in advertising. You go into the bathroom and you look in the urinal and you're staring at an ad. You look up at the sky and there's skywriting."

This clutter creates a dilemma for advertisers, Garfield observes. "The advertisers know they need to have more and more advertising to get an ever narrower slice of your attention," he says. "And that means we are going to be ever more inundated. And then of course ever more resistant, requiring ever more advertising, making us ever more resistant and so on."

But clever marketers have found ways of overcoming the clutter conundrum. As television viewers have found ways of avoiding ads by using personal video recorders like Tivo, advertisers have responded by becoming a part of the program through sophisticated product placement. FRONTLINE follows this new trend in advertising known as "branded entertainment." Rather than marketing products around a TV show or other entertainment vehicle, industry insiders predict the future will bring a seamless blend of marketing and entertainment. Producers are already moving in that direction. Take for example a recent Sex and the City story line in which a character becomes a poster-boy for Absolut Vodka. The idea was actually proposed to HBO by Absolut's public relations agency.

Some industry leaders claim that such tactics have evolved in response to consumer preference. But others worry that as advertising becomes more deeply integrated into television, movies, and music, those cultural forms will become ever more homogenous. "The worry is not so much that the actual ads themselves will become ubiquitous," says media critic Mark Crispin Miller. "Rather, it's that advertising desires for itself a background that will not contradict it….The aim here is not so much to find a show that people like and then get your ads on it. The aim here is for the advertisers to create a show that is itself an extended ad."

As consumers grow more cynical toward marketing claims, the persuasion industries are developing and refining techniques to reinforce an emotional attachment between Americans and the brands they buy.

"What consumers want now is an emotional connection—they want to be able to connect with what's behind the brand, what's behind the promise," says Kevin Roberts, CEO of Saatchi and Saatchi Advertising. "The brands that can move to that emotional level, that can create loyalty beyond reason, are going to be the brands where premium profits lie."

Douglas Atkin, a partner at advertising agency Merkley + Partners, goes even further, comparing the brand loyalty that companies are trying to create to the passionate zeal once enjoyed only by cultists and religious fanatics.

"I've interviewed people who are brand loyalists of Saturn Car Company," Atkin says, "and they will use the same vocabulary as someone who is a cult member of Hare Krishna. They will say that other car users need to be `saved,' or that they are part of the `Saturn family' with no hint of irony. [They] absolutely and completely believe it."

Although some brands have been more successful than others in making the magic connection to consumers, the techniques the marketers are developing are startling and include the hiring of anthropologists, ethnographers, linguists, and brain researchers to plumb our unconscious desires and urges so as to better influence our decision making.

But there is reason to wonder if these emotional connections are real. Says author Naomi Klein, "When you listen to brand managers talk, you can get quite carried away in this idea that they actually are fulfilling these needs that we have for community and narrative and transcendence. But in the end it is…a laptop and a pair of running shoes. And they might be great, but they're not actually going to fulfill those needs."

Correspondent Rushkoff observes: "We Americans value our freedom of choice—choice in the marketplace of goods, and choice in what has become a marketplace of ideas. When the same persuasion industry is engaged to influence these very different kinds of decision-making, it's easy for our roles as consumers and our roles as citizens to get blurred. By revealing some of the most effective practices of the persuasion business, we may better understand our choices and perhaps make wiser ones."