Gene and Sherry Pittman aren't buying as much as they used to these days. Only four months ago, the Pittmans, both 32, were spending freely, impulse-buying with credit cards in twice-a-week jaunts to the local shopping center.

Now, however, with their incomes eroded by inflation and the economy in the throes of a recession, the Carrollton, Tex., couple has cut back on all but "necessary" purchases and begun paying cash for everything but gasoline.

"I don't foresee us ever going back to the kind of charging we did," Gene Pittman says, recalling the $1,500 a month in outstanding credit card debt that the Pittmans routinely carried before their self-imposed cutback.

More important, the way things stand right now, the Pittmans aren't even sure they'll step up their buying much at all in the next several months. The outlook, Gene Pittman notes glumly, "is not very good."

The Pittmans' middle-income take-home pay -- ironically, he's manager of a credit union -- may not have much weight in a $2.9 trillion economy. But if their mood is typical of many Americans, it could spell trouble in the months ahead.

With the economy now unmistakably in a recession, many analysts believe it will be primarily consumer spending that will determine how deep and long the downturn will be.

Analysts say if consumers begin spending again soon, the recession could prove "mild and short," as President Carter and his top economic adviser have predicted.

But if workers continue to hold back, the recession could well be severe -- possibly as deep as the 1974-75 downturn, which was the worst in 37 years.

Such new worries about prolonged consumer retrenchment may seem inconsistent to many Americans -- and understandably, in view of the past few months' developments.

It was only 12 weeks ago that the White House was complaining that Americans were spending too freely and exacerbating inflation. The president's move to impose credit controls was intended to slow down the buying binge.

Now, barely 30 days after the administration's action, there's concern that Americans may have overreacted. Many consumers -- and a good many members of Congress as well -- are asking who turned out the lights?

The fact is, what policymakers are seeking is a balance -- to end the speculative fever of late 1979 and early this year, yet keep spending at a moderate-enough pace to ward off a really severe recession.

President Carter conceded before a campaign audience last Friday that the Fed's recent credit restraints had had an impact "many times greater than what we'd thought." But he predicted a "quick rejuvenation" in consumer spending.

However, whether that actually will happen still is far from certain. Thomas Juster, director of the University of Michigan's Survey Research Center, says polls of consumer sentiment showed near-record pessimism in March and April, accompanied by dismall expectations on future personal finances.

"It's not dissimilar to the sort of 'air pocket' we found in August 1974, just before the big recession," Juster said in an interview last week. "The buy-now philosophy is gone. It's as bad as it has been in three decades."

Moreover, neither Juster nor any of his surveyer-colleagues sees much on the horizon to turn consumers around any time soon, particularly in the face of continuing adverse economic statistics.

It was the failure of consumers to follow usual patterns that forestalled the recession in 1978 and 1979, even in the face of soaring inflation and declines in real income.

Traditionally, when inflation starts to speed up and prices outstrip the increase in real incomes, Americans tend to retrench, figuring they'll cut back their living standards until prices and incomes get back into line.

The economy promptly turns down, and the needed adjustment is made.

Last year, however, consumers not only kept on spending, but they went on a buying spree -- spurred in part by the belief that they'd better buy now or face still higher prices later.

They also bid competively for property ans assets -- as an added hedge against inflation. The result: Demand accelerated even more and fueled inflation still further.

Until early this year, consumers were able to keep up their previous living standards -- and their buying levels -- through some profound changes in the U.S. life style:

They dipped heavily into their savings accounts, pushing the percentage of disposable income that Americans actually save each quarter from 5.4 percent in mid-1979 to 3.4 percent early this year.

They bolstered sagging bank balances by refinancing their homes -- using the increased equity built up from the recent surge in house prices to provide cash for purchases of big-ticket items.

They went heavily into debt by buying on credit cards and running up huge balances in revolving charge accounts. (Ironically, in some states, the loans proved a bargain: Interest rates were below the inflation rate.)

Married women went back to work in droves, mainly to add to the family income. The Labor Department estimates about 50 percent of U.S. married women now work at jobs away from the home -- an all-time record.

With all that momentum and new financing, the economy refused to quit. It seemed as though the nation simply was refusing to go into the predicted recession.

The turnaround came in late February and early March, as consumers were hit with a barrage of adverse economic developments:

The 18 percent inflation rate that burst upon the economy early in the year sent shock waves through the country, making consumers edgy about what was likely to happen next. In 1979, consumer prices had risen 13.3 percent.

Interest rates, particularly for home mortgages, shot up to record levels, making it too expensive to take out a home loan even in cases where credit was available. Many thrift institutions shut down lending altogether.

The Federal Reserve Board's new crackdown on credit-card issuers -- while needed to help end the binge consumers were on last year -- apparently prodded buyers into cutting back their credit card use far more sharply than expected.

Many retailers, among them Sears, Roebuck & Co., have begun trying to counter that notion by sending notices to customers encouraging them to use their cards. In the meantime, the perception has dampened buying.

The reality of the current recession -- and widespread layoffs in the auto and steel industries -- has made consumers more pessimistic, and decidedly more cautions about buying, than they were anytime last year.

As a result, both consumer spending and credit card use have plummeted in recent months, helping to drag the economy into its recession.

Retail sales, the broadest monthly measure of buying activity, plunged 1.5 percent in February and 1.3 percent in March -- after remaining ebullient through the beginning of this year.

And consumer credit slumped in mid-February, with the increase in the amount of new credit extended slowing to 1.6 percent for that month and then declining by 1.6 percent in March.

Economists expect a similar pattern in April, and see little sign of any visible pickup in the near future.

The Carter administration is expecting the consumer price index to slow later this year to 10 percent or so from the 18 percent that prevailed in the first part of the year, but even that would be high by most standards.

And even if consumers were inclined to buck the tide again this year, most of the ploys they used in 1979 no longer are open to them:

Savings levels already are unusually low, and analysts figure that with the recession now so apparent, consumers won't want to drain their accounts much further -- and may even try to build them back up again.

(If the savings rebounds even a percentage-point or so back toward its historical levels, it would amount to a major long-term retrenchment with significant implications for the strength of the economy.)

With the number of jobs in the economy declining, wives won't be able to find work as easily as they did last year. Indeed, many newly working women may well be furloughed if the downturn worsens.

The Federal Reserve Board has cracked down on the growth of credit card debt, making card-issuers reluctant to allow substantial amounts of new borrowing.

The recent rise in interest rates has crimped the housing market severely. It is difficult to find refinancing for existing homes, and when available, it's usually at a high cost.

As a result, most signs now point to continued retrenchment by consumers, and a deeper-than expected recession as well.It's up to Gene and Sherry Pittman how long the downturn lasts.