What should I buy?

What do I want? What do I want? It is a question that permeates American life.

It follows us down the well-stocked aisles of the local supermarket. What do we want? Like a good book, it noodles with our deepest yearnings for purpose. What do we value most? And what is it worth to us?

The marketing man needs to know. His search for what we want has taken him well into territory once left to poets and anthropologists - the hearts and minds of Americans.

Everyone wants something different, but there have always been patterns. On one level, housewives supposedly want whiter whites. On another, parents have generally been willing to sacrifice so that their children can have more than they had.

In the past decade, the patterns have been disrupted. Americans are wanting different things, different from before, different from one another.

Market researchers, in a field they call psychographics, are busy charting this terrain - plotting the attitudes, interests, and life styles of various segments of the buying public - to draw up good, usable maps.

If there are common landmarks used by these explorers of consumer attitudes, they are those mapped by the VALS program at SRI International in Menlo Park, Calif. VALS stands for Values and Life Styles, and it divides American consumers into nine basic ''VAL types'' (see box).

To be useful to marketers, the maps must help explain changes of heart like this:

A corporate pin-striper - an overachiever - commutes an hour and a half each way to a demanding, high-paying job in a big city. Howard Leonard, research director at Young & Rubicam, a national advertising firm, sets up an interview with him weeks in advance as part of an in-depth probe of consumer values.

By the time Mr. Leonard pays his visit, the man has stood his life style on its head. He has decided he wants more time with his wife and young son, trading his career for a much lower-paying, part-time job nearer home. Now he is considering work in a small local store, just for a fresh experience.

This is an unusual fellow, but he illustrates some notable trends tracked by marketing people around the country:

* Renewed interest in the home and in personal relationships.

* The steadily increasing value placed on simplicity and balance in daily life, with less waste or excess.

* A growing sense of the preciousness of time, that time is worth more than money.

* A new desire for full, rich experiences for their own sake, rather than as a means to an end.

These things translate into buying habits, the theory goes.

But the most pervasive yearning of all seems to be for quality. From quality of life to quality of cars and cameras, Americans want it in any number of ways for any number of reasons. On the one hand it can mean a new respect for excellence, on the other a new elitism.

People are buying less because of a less-abundant economy, marketing analysts say, but what they buy today will tend to be better-made, better-looking, and more enduring.

The 1960s came and went with much social tumult, but they left the great bulk of American values virtually unchanged, says Daniel Yankelovich in his 1981 book , ''New Rules: Searching for Fulfillment in a World Turned Upside Down.'' But the past decade has seen these values quietly revolutionized.

Mr. Yankelovich is the dean of market researchers, and for 12 years his Yankelovich Monitor has tracked shifts in the social climate for subscribing corporations and agencies, looking at some 40 social trends.

The results are closely guarded, since the subscribers pay handsomely for them. But a central thesis in Yankelovich's book is the decline of the ethic of self-denial - the credo that long ruled family life in this country - in favor of the quest for self-fulfillment.

That quest has come with easy affluence and the rapid changes in all aspects of social life, Yankelovich says. These changes have been so profound that people feel the old rules no longer apply.

The affluent American faces open-ended choices on all sides. And now the pinching economy demands a cutting back and taking stock: The kid in the world's largest candy store just found he has but 30 cents in his pocket.

Faced with great freedom of choice, people yearn for limits, for meaning, for new rules with which to sort out what they want. Out of this yearning, a new and more mature ethic of commitment may emerge, as Yankelovich optimistically believes. But for now the upshot is anxiety.

Hence, Jill Himonas, recently senior vice-president for marketing cosmetics with Max Factor and now with the advertising agency Ogilvie & Mather, points to ''an incredible degree of stress in the early '80s.''

Life holds too many choices. ''People feel the need to explore them all,'' she says. Reared with a strong sense of entitlement to the good things in life, the children of the postwar baby boom ''deny themselves nothing.

This translates - among other things - into a market for prestige and luxury items among these tense, self-indulging consumers. Many of them are single, as the number of one-person households is nearly a quarter of the nation's total. Many others are one of two working members of the household, as women continue streaming into higher education and the work force.

Ms. Himonas says they will be increasingly sophisticated and discerning as consumers.

She foresees five prominent consumer types in the '80s, drawing from the Yankelovich Monitor, SRI's VALS program, other data sources, and her own observations:

* The value-conscious buyer. Not a cheapskate, but looking for value; willing to work for better quality per dollar, as in ''fixer upper'' houses and bargain antiques hunted down in the country.

* The time-conscious buyer. Will spend money to save time; seeks efficiency and convenience; is likely to be seen eating at a Mexican drive-in or a fast-food croissant stand.

* The ''me''-conscious buyer. Loves to shop and is seeking status and prestige. Look for the designer label on his or her jeans, sheets, and chocolates.

* The stability-seeking buyer. Looks for things that will last, that afford a respite from a confused world, so seeks classics and demands authenticity.

* The single buyer. Shops for one, buying small cars and small condominiums and avoiding gallon containers of milk.''All of these consumers are seeking quality,'' Himonas observes, ''but they all define it in a little different way.''

Psychographic researchers try to make some practical sense of the kitchens and family rooms of American life - not to stereotype individuals, but to plot their basic tastes. Here are four typically peculiar, peculiarly typical, Americans encountered by Howard Leonard of Young & Rubicam:

1. Call him Bill. He lives in the Northeast in a handyman special of a house with his wife and nine kids. He was an upholsterer until a few years ago. Now he is a cook in a state institution and does odd jobs - lawns, painting, fix-it work. Financially, he scrapes by. He doesn't use credit.

By his own labor, he expanded the house to 12 rooms. His wife grows vegetables in the garden and does her own canning. They read the neighbor's newspaper when he is through with it. Bill watches ''action'' shows on television. The family has never had a vacation. Bill is a ''sustainer.''

2. Kathy is a different story. Drawn to New York by an art festival a couple of years ago, she stayed. She has tinkered with extrasensory perception and mysticism. She is a bookkeeper, and works flexible hours. Weekends, she sky-dives and scuba-dives.

''The only time you're really alive is when you're stepping out the door of an airplane,'' she told Leonard. He classifies her as ''experiential.''

3. John travels widely and often. Still youthful, he is head of a major division of a major company. He knows where he is going: He aspires to the top.

John loves his work, but he struggles with balancing his ambitions with time for his family. Once he thought he would not willingly sacrifice his home life in his quest to head his company. Now, he says, ''I guess I'd be willing to make those sacrifices.'' John is a textbook-case ''achiever.''

He wants and buys little in common with Louise.

4. Louise met most of her friends through volunteer work with Welcome Wagon. She lives in a small house in a small town, and her husband is a furnace repairman. Louise hopes their son will go to college someday, or acquire job skills. Her daughter, she says, should go to secretarial or computer school and not marry too early.

Louise buys familiar brands and is an avid coupon clipper, often trading with her neighbors. The family sometimes eats out at local diners, except when the kids push for McDonald's or Burger King.

Louise, Leonard notes, is a ''belonger.''

Salespeople at New York Telephone's Phone Center stores rely heavily on SRI's VAL types to sell telephones. They begin by listening for certain key words when talking to a phone shopper about his home.

Words like ''homey'' that stir up visions of conventional comfort call not only for certain decorator phones, but also a distinct style of salesmanship. These customers are ''belongers,'' and they prefer to deal with an avuncular salesman who presents himself as a trusted adviser and friend.

Words like ''elegant,'' which deal with style, flag the ''achiever'' type. Achievers want the services of an expert, a telephone consultant - not to tell them what to do, but to inform their decision.

''Emulators,'' on the other hand, mostly respond to someone who can tip them off as to what the big-timers are buying.

The New York Telephone Company has had great success in ushering in new lines of decorator phones by positioning two phones in each of the major VAL categories. Before, they found they had too many phones competing for some groups and none for others. (AT&T provides the phones, but New York Telephone decides what to order and where and how to sell them.)

Two phones it introduced last December using this plan have become the second- and third-best-selling decorator phones overall: the ''Doodle'' for ''belongers'' and the ''Rendez-vous'' for ''achievers.''

Unlike the trend tracking of Yankelovich Monitor, which describes consumers according to clusters of computer-processed characteristics, VALS is based on theory derived from behavioral science.

In this sense it's less objective. But it also gives a clear framework for planners to work from, and a common language for marketers to speak when discussing their target markets. It makes consumers easier to talk about.

There are currently 70 or so corporate members of the VALS program. They use this strategy to market everything from hotels and restaurants to automobiles and stock brokerage services.

The prominent ad agency Young & Rubicam bases much of its work on VALS. ''I find my clients are fascinated with doing this,'' says Renee Fraser, West Coast research director, ''even if they don't do anything with it. It gives them the reassurance that we know where things are going.''

VALS has its limitations. Any attempt to segment consumers, says Sonia Yuspeh , research director at J. Walter Thompson, another ad agency, can distort the truth. ''You may be a penny-pincher in one (product) category and splurge in another.''

The field grows because computers have made it easier and because traditional demographic research didn't tell marketers enough, sums up Leon Schiffman of Baruch College in New York. Dr. Schiffman is a marketing professor and a longtime consultant to AT&T.

Marie Spengler, director of the VALS program, has another explanation: ''One of the overarching conclusions we came to is that we're growing much more diverse (in our values).''

This growing diversity may be why marketers no longer feel they can target the broad traditional segments of American society.

In the 1950s the United States was a much more homogeneous society, much more apt to follow the crowd, according to Ms. Spengler.

''Marketers became very good at creating images. In the '70s, a new diversity has developed. Change has come fast, and (marketing) people are slow to give up something they have become good at.''

Looking across the whole band of consumer values, Dr. Schiffman sees much more conservativism ahead. By conservatism, he means elitism and a respect for excellence. In a word, quality.

To him, this translates into a moving away from marketing altogether and back to a stronger emphasis on quality in production and engineering. ''I think people feel we're not going to be able to compete without more excellence. We've let the consumer make all the decisions. We may know better what he needs.''