On any given 2 1/2 hours of Saturday morning TV, your child will be exposed to 50 or more commercials. On the morning that I watched there were: 14 ads for fast food places, 10 ads for ready-to-eat cereals, 7 ads for frozen treats, 5 ads for toys, 4 ads for movies, 4 ads for cookies, 3 ads for soft drinks and punches, 2 ads for fruit snacks, and 1 each for chips, milk and the say no to drugs campaign.

How much impact do commercials have on children? Does the fact that your children are always wanting to go to McDonalds have any relation to the fact that the fast food place is one of the most frequent advertisers on Saturday morning television? Do children want to eat more sugar-coated cereals because they have seen them touted on their favorite cartoon shows?And what are the long-term effects of this early exposure to advertising? Do children who watch a lot of ads tend to want more things, be more materialistic?

These are important questions. And the answers are not all in yet, says Deborah Roedder John, associate professor of marketing at the University of Minnesota, who has been doing research in this area.

But it is an area that is attracting a lot of interest-- and that's not surprising, when you consider a few statistics.

Best estimates, says John, are that advertisers spend $100 million a year on Saturday morning advertising aimed directly at kids. Of course, there are ads on at other times of the week that also target youngsters, but those figures are harder to sort out.

The largest amount is spent on ready-to-eat cereals and snack foods, she says, followed by toys and games. These categories account for about 75 percent of all kid-targeted advertising.

And just why are children becoming an increasingly popular advertising target?

There's more to the demographic group than you might think, says John. For example, James MacNeil, author of the book "Children as Consumers," estimates that children between the ages of 4 and 12 have $4.2 billion in discretionary income a year-- money that comes from allowances, gifts, chores and so forth that they can spend on things they want to buy.

Another point is that children have influence in a wide variety of family decisions: entertainment, movies, amusement parks, vacations, dining out.

"The influence of children is widespread-- even on products they don't purchase," says John.

Population watchers are expecting an increase in children ages 4-12 in the next 10 years, as the so-called "baby boomlet" comes along-- baby boomers having more babies themselves.

There are also more children now born to more two-income families, and those families tend to spend more on their children.

So, perhaps it is not surprising that advertisers are looking at children as an important, active market.

But how are the children responding?

First, a little history.

In the late '70s, says John, the Federal Trade Commission proposed a rule that would eliminate advertising aimed specifically at young children, based on concerns that the ads were unfair, that they take advantage of a group that does not have a complete grasp of what is going on.

The proposal stirred up a lot of controversy, the FTC held hearings, and eventually the proposal was dropped.

But that doesn't mean the concerns went away. And researchers began looking into the matter to see how much children really do understand about the commercial pitches.

The findings substantiate just what you might expect: the younger the child the less he or she understands about the intent and techniques of advertising.

Age 8 seems to be the break point, says John. "Children under age 8 do not have as much ability to recognize that the company is trying to sell a product, that it might use exaggerations. Younger children have a harder time distinguishing between what is really a commercial and the regular program; they tend to see the commercials as a continuation of the program."

Studies show, she says, that younger children tend to pay more attention to commercials than older ones; they tend to pick up the jingles and songs.

And, she says, while all children tend to request purchase of items they have seen advertised on TV, those under 8 may make more frequent requests.

Another issue that has come to the forefront recently is the fact that more and more Saturday morning TV programs have product tie-ins-- to toys like Care Bears and Masters of the Universe and Rainbow Brite and others.

Do children who watch these shows want to buy more of the toys? "Some of the program are really like a 30-minute commercial," says John. There are many people who feel that this type of programming is too commercial, that it might not be the best kind for children to be exposed to, she says.

Research is still sketchy on the long-term effects of advertising, she says. Some studies show that heavy exposure to ads may lead to increased consumption of certain foods-- sugar-coated cereals, snacks, etc. There is also some evidence that heavy exposure tends to increase use of perceptual features-- such as color of package and shape of cereal-- rather than functional features --such as type of grain, ready-to-eat vs. cooked-- in making product choices.

Does heavy exposure lead to a more materialistic view? "We see children begin to attach values to products at early ages. Children start hanging on to status symbols even in the early elementary grades. This is party because of advertising and partly because of peer pressure," says John. But there is still not enough concrete evidence on long-term effects to draw too many conclusions.

Clearly, advertising aimed at the children's market is not going away-- at least in the near future. And it will be a hot topic for research in coming years. We may also see increased debate in the public policy arena. Congress, for example, is currently considering a proposal to limit the number of minutes allowed for advertising on Saturday morning TV programs.

In the meantime, is this something parents should be concerned about?

"The majority of parents don't talk much about advertising," says John. "Part of the reason may be that we think children are so sophisticated in other ways that we think they understand all the subtleties. But perhaps we need more interaction, particularly with children under 8."

Instead of getting cross with children when they ask you to buy products they've seen advertised, you might want to sit down and talk about ads. Watch the ads with your children. With younger children, you might just explain the difference between commercials and programs, talk about how companies are selling products, and that you can't buy everything you see on TV. With older children, you could discuss such questions as: What does the company want you to do? What do they say that makes you want to buy the product? Are there things they don't tell you about the product?

You may also want to talk about times when you bought a product that was advertised and it didn't live up to expectations.

Other studies have shown that children can learn to sort out specific features of advertisements if they are given some direction, but parents need to get involved.