Economists have only recently devoted serious study to how a decline in housing prices affects consumer spending, not least because this is the first decline in the average price of an American home since the Great Depression. A 2007 review of existing research by the Congressional Budget Office reported that people reduce spending by $20 to $70 a year for every $1,000 decline in the value of their home.

This “wealth effect” is significantly larger for changes in home equity than in the value of other investments, such as stocks, apparently because people regard changes in housing prices as more likely to endure.

A recent paper by Karl E. Case, an economics professor at Wellesley College, and two co-authors estimated the decline in home prices from 2005 to 2009 caused consumer spending to be $240 billion lower in 2010 than it otherwise would have been. That figure is equal to about 1.7 percent of annual economic activity, enough to be the difference between the mediocre recent growth and healthy growth. And it does not include all the other effects of the housing crash, including the low level of new home construction, that are also weighing on the economy.

Roy Pugsley, who owns a pool supply store in Winter Garden, another suburb here, said that he made 2,500 fewer sales during the first eight months of 2011 compared with the same period in 2007. That translates to one less person walking through the doors to buy chemicals or toys or spare parts in each hour that the store is open.

Mr. Pugsley said business actually increased in the early days of the recession; customers had told him they were spending more time at home. But now people buy only what they need for maintenance. “People realized that it wasn’t going to get any better, and they stopped spending on their pools, too,” he said.

At Milcarsky’s Appliance Center in the adjacent town of Longwood, business now comes from people remodeling their own homes rather than builders, and customers are picking cheaper models, said Doug Morey, a sales manager.

“People who might have bought that” — he taps a stove with chunky burners, designed to look like it belongs in a restaurant kitchen — “are double-thinking it. Everyone has had to cut back.”