When the producers of the new "Teenage Mutant Ninja Turtles" (TMNT) cartoon began thinking about a model for the program they launched last month, they did not look to kid culture, but to HBO.
4Kids Entertainment, which produces the cartoon and licenses the toys the show helps to sell, wanted to draw kids into the world of the turtles in ways that no other cartoon had ever done.
Part of their task was designing a cliff-hanger cartoon with a story line that children would devotedly follow week by week. The program that seemed to most offer what they were looking for: "The Sopranos."
"We're trying to emulate what works well in prime time," says Norman Grossman, president of 4Kids Entertainment, which produces TMNT, among other cartoons. "We thought of all those people who can't wait to see the latest episode of 'Sopranos.' "
The serial format for their cartoon is just one example of how the Turtles have changed. The original cartoon aired about 1990, having made the leap from the comic-book world.
The turtles themselves are no longer primarily benign pizza-eaters who kid around with one another and get into skirmishes, but tough-and-buff dudes who disperse a few clever lines between prolonged combat scenes.
And the cartoon itself is no longer just a vehicle for marketing toys. Marketers now use cartoons to introduce children to a much more elaborate world of characters, details, and plots that extend from the TV to the Internet, video games, and a range of licensed products.
The evolution of the Turtles over the past decade shows how far marketers have come in understanding children's culture, and the lengths they now will go to win their attention.
"We're looking for things we can put on the air and extend into kids' lives in a variety of ways," says Mr. Grossman. "We're not only looking for ratings, but to get into kids' psyches on a day-to-day basis."
The experience of marketing the Pokémon brand over the past five years taught 4Kids a key lesson: Children like their current entertainment fad to be all-consuming. It is up to those who market the brand, according to 4Kids, to create a critical mass of details that they can strive to master.
"It was very clear from the beginning that if we could somehow harness the power of why kids want to learn details, it would be a very powerful thing," says Grossman.
After watching children pour themselves into Pokémon, Grossman and his colleagues came to the conclusion that children soak up details because they want to become experts at something of which adults have no understanding.
Because the cartoon is in a serial form, Grossman believes children will keep thinking about the TMNT narrative during the week, and talk about the show with their friends.
"If we can get them into the TV show, that's when they start sucking up the land of the turtles," says Grossman.
The details in the programs will pop up on the TMNT website, in comic books, trading-card games, videogames, and a variety of other licensed products.
"We hope it's the subject of discussion in the schoolyard, at the water fountain, and that they check it out online to see if we give advanced hints about what the story will be next," says Grossman.
That level of engagement might be unlikely among the age group to which the first cartoon was pitched: 4- to 8-year-olds. But 4Kids, like many entertainment companies over the past decade, has broadened its product's demographic base. Marketers in general have become more sensitive of late to younger children's interest in entertainment and products clearly designed for an older audience.
Partly for that reason, 4Kids chose to design the new cartoon to appeal to 9- to 14-year-olds. The producers' expectation: Younger children will be pulled along.
"Younger kids will want to emulate older kids. They are going to watch this kind of show anyway," says Grossman. "If it's just for younger kids, that's a turn-off for the older kids who don't want to be seen watching those shows."
Other observers say that the show also is likely trying to attract young parents in their 20s who watched the first program when they were adolescents and want to pass on to their children their pop-culture memories.
The result may aptly be thought of as "Sopranos Lite": a cartoon with themes that are more dramatic and emotionally sophisticated than those to which most children are accustomed.
"In trying to appeal to a wider age audience, like many cartoons, the show has gotten much darker and violent," says Diane Levin, an education professor at Wheelock College in Boston.
Another reason for the violence may be marketers' perception that combat sells. In his 1962 essay "Social Learning Through Imitation," sociologist Albert Bandura argued that individuals, especially children, tend to imitate media violence more than most other emotions.
Action figures, according to some studies, are the ideal toy for accommodating their need to mimic. Of course, violence in cartoons is a trend older than Bugs Bunny. But several experts believe the drive to sell toys is so intense that conflict is being used much more consistently.
"These violent programs are now almost always product related and toy driven," says Kathryn Montgomery, president of the Center for Media Education, a nonprofit group in Washington.
The creators of the new "TMNT" argue that the violence does not go too far. They also defend the heavy toy marketing by arguing that, without such products, kids' entertainment would be hard to find. "If we didn't have products available that represent these shows," says Al Kahn, 4Kids owner, "no shows for kids would ever be available, including 'Sesame Street.' "
In toy stores, what's old is new again.
Some of the latest toys to hit store shelves include several names that hark back to the Reagan administration. Among them: He-Man, My Little Pony, Silly Putty, Strawberry Shortcake, Teenage Mutant Ninja Turtles, and Transformers.
Their appearance is surprising in an industry where all but classic toys like Barbie tend to stay in retail for only a few years before they leave kid culture for good.
The return of toys introduced a generation ago, say experts, is in large part a generational effect. These toys were among the first to be marketed primarily through TV cartoons. The result: The toys carried with them a much stronger brand identity than toys from previous eras.
When those who played with these toys during the 1980s recently began having children of their own, marketers realized they could take advantage of parents' sentimental ties by bringing the toys back.
"We're starting to see a lot of properties and products regenerating now for the kids of Generation X," says Greg Livingston, executive vice president of Wondergroup, a children's-product marketing firm.
But other industry observers say the retro-toy trend is more rooted in basic economics. When the economy isn't strong, they say, toymakers get conservative.
One of the safest marketing tactics is bringing back toys that are proven successes.
"If you're in the business of making and selling toys, you're going to go the safest route, which is using proven commodities," says Stephanie Oppenheim, cofounder of the Oppenheim Toy Portfolio, an independent consumer group that rates toys.
Other companies, like 4Kids Entertainment, which produces Yu-Gi-Oh, uses product ideas that have sold well in other countries, such as Japan.
Still, Ms. Oppenheimer also believes that American consumers simply are not in the mood for innovative, high-tech toys anymore.
"People are interested less in what we wish we had and more in what we already have," says Oppenheimer. "As a country, we're looking for things that remind us of simpler times."