WASHINGTON – Growing numbers of middle-class Americans say they aren’t better off than they were five years ago, reflecting economic pressures amid growing debt, a study released Wednesday shows. Their short-term assessment of personal progress, according to the study, is the worst it’s been in nearly half a century.

The survey by the Pew Research Center, a Washington-based research organization, paints a mixed picture for the 53 percent of adults in the country who define themselves as “middle class,” with household incomes ranging from below $40,000 to more than $100,000.

It found that a majority of middle-class people said they haven’t progressed in the last five years. One in four, or 25 percent, said their economic situation had not improved, while 31 percent said they had fallen backward. Those numbers together are the highest since the survey began in 1964.

Middle-class prosperity also lagged compared to richer Americans. From 1983 to 2004, the median net worth of upper-income families – defined as households with annual incomes above 150 percent of the median – grew by 123 percent, while the median net worth of middle-income families rose by just 29 percent.

“It’s been a lousy run for the American economy and people feel it,” said Paul Taylor, director of Pew’s Social & Demographic Trends project and author of the study. He noted that people’s pessimism largely tracks annual median household income, which has seen little gains in recent years.

The Pew poll involved telephone interviews with 2,413 adults, conducted from Jan. 24 to Feb. 19. The margin of sampling error was 3 percentage points.