While the Dow Jones industrial average and the unemployment rate get more attention, the shoppers outside a Wal-Mart in Northern Virginia offered a taste of what some economists believe is the more immediate reason that the U.S. economy may be on the verge of another recession.

Americans are still spooked.

More than two years after the recession’s official end, people are driving their cars a year longer, holding back on jewelry and furniture, and swapping brand names for cheaper store brands at the supermarket.

More ominously, the once sturdy optimism of Americans appears to have crumbled, according to one key measure. Breaking from precedent, Americans no longer believe they will make more money next year than this year, according to the University of Michigan’s Surveys of Consumers. These expectations used to rebound after recessions; this time they didn’t.

This crisis of confidence, a departure from long-standing expectations of rising American prosperity, is spurring millions of small consumer decisions that collectively determine whether businesses should expand, and in turn whether the recovery will continue to falter.

“I don’t get the Kellogg’s cornflakes anymore,” Robert Sherman, owner of a heating and air-conditioning company, said last week outside a Wal-Mart near Alexandria. “I’m not taking vacations. Why? I’m scared.”

Shah Bahramy, a retired physician who dropped Macy’s in favor of Ross Dress for Less, said, “I’m trying to be as conservative as possible.”

Linda Bailey, an insurance agent, recently traded Heinz ketchup for a store brand and came to Wal-Mart last week, although she would have preferred a smaller store. “Fear is driving things,” she said. “We really don’t know what’s going to happen, do we?”

As recently as March, Federal Reserve Chairman Ben S. Bernanke, citing rising consumer spending and other factors, foresaw “a somewhat more rapid pace of economic recovery.”

Before his statement, consumer spending — which represents a significant portion of economic activity in the United States — had been on a steady rise from the depths of the recession.

But every month since then, reports on consumer spending have slumped — just a little each month, but the acceleration of the recovery was gone.

Jittery consumers

One of the key reasons appears to be that American consumers are nervous.

Since 1981, the University of Michigan’s Surveys of Consumers have asked people, “By about what percent do you expect your [family] income to increase during the next 12 months?”

In the early 1980s, respondents estimated that they would make about 4 to 5 percent more in the coming year. Over the 1990s and early in this decade, that figure dropped to about 2 percent. And then, with the recession, it dropped to nearly zero, where it has remained.

Moreover, the nation’s largest retailers, which monitor the pulse of American consumers most closely, have offered little good news in recent months.

During a recent call with analysts, William Simon, president of Wal-Mart U.S., noted that “customers remain under continued pressure.” They are trading down to cheaper products, choosing smaller packages and forgoing discretionary buying. More customers are relying on government assistance for food and other necessities. And the “paycheck cycle,” in which consumers buy less as they run out of money at the end of the month, “remains pronounced.”

“Food inflation has replaced gasoline price as the most important household-expense concern,” he said.

At Kroger, meanwhile, chief executive David Dillon reported in June that the recovery seemed to have stalled, at least from the supermarket chain’s point of view.

“What we’ve seen is things have stagnated a little bit in the economy and behavior has sort of just plateaued there,” he said.

And at Target, executives noticed a drop in confidence but not a uniform one.

Customers in the higher income levels, they said, have been willing to spend more on clothes and on home furnishings from brands such as Fieldcrest Luxury and Smith & Hawken.

“Wealthy households continue to be the most optimistic,” Kathy Tesija, Target’s chief merchandising officer, said in a conference call last week. “Across all of retail, the 20 percent of households with the highest incomes are shopping more often and spending more.”

The other 80 percent?

They’ve “been cutting [shopping] trips and spending less,” Tesija said.

Economists cite many reasons for consumers’ loss of confidence. The lofty unemployment rate continues to put downward pressure on wages; the fractious debate over the nation’s debt has eroded faith in the nation’s politics; and the huge debts that Americans ran up during the boom have yet to be repaid.

Self-fulfilling prophecy

In the United States between 2000 and 2008, outstanding consumer credit and home mortgage debt rose rapidly, from 65 percent of gross domestic product to more than 90 percent.

That ratio has since fallen to 85 percent, but it could take many years for households to reduce what they owe and feel free to spend again, economists said.

Until then, the decline in consumer confidence could become a self-fulfilling prophecy if, as a result of fear, they continue to cut back spending and lead businesses to cut back as well, some economists said.

That could begin a cycle of dismal expectations and set off another downturn.

“It could be the only recession that we actually will ourselves into,” said Mark Zandi, chief economist for Moody’s Analytics.

“The trouble is people are so shellshocked and haven’t really gotten over the recession,” he said. “They’re extraordinarily nervous, and when anything goes off script even a little bit they freeze, and that’s where we are right now and why we are so close to recession.”