We tend to think that people who go into foreclosure are forced to do so because they can no longer afford to pay their mortgage.

But a recent report looks at the social consciousness of the 25 percent who default on their home loan even though they can afford to keep paying. They walk away from their homes and their loans because they're under water, owing more than the house is worth.

The report, "Moral and Social Constraints to Strategic Default on Mortgages," was authored by three professors, including two from Chicago: Paola Sapienza of Northwestern University and Luigi Zingales of the University of Chicago. Luigi Guiso is the third author.

As you might expect, the road to default is complicated by a number of factors: how long the owners lived in the home and how much equity is built up, as well as their own desire to stay or go. Owners whose home values dropped 20 percent or less tend to stay and pay.

The researchers asked: If you can afford to keep your home and pay your mortgage, then should you do so, even if you owe more than the home is worth? Is it morally wrong to walk away?

Of their respondents, 81 percent said it was morally wrong to default when you don't need to. Those under 35 were 12 points more likely to think it was OK to default, and owners over 65 also were less likely to see it as wrong. Homeowners with more education were more likely to think it was wrong, as were more wealthy people. African Americans were 14 percent more likely than other racial groups to see it as morally wrong. Default was less of a moral issue for those living in the Northeast and the West. Republicans were the most likely to see it as wrong, followed by Democrats; the least bothered by the morality of default were independents.

Interestingly, the likelihood that someone might voluntarily default was higher if they knew someone else who had done it. The authors suggest that there is a solid domino effect among foreclosing households. Once someone they know has done it, the stigma lessens and off they go.

"Both the Bush and the Obama administration policies," the authors write, "are based on the presumption that the current housing crisis is only due to the excessive burden current mortgage payments imposed on many households. No attempt has been made to resolve the negative equity problem."

With the number of underwater loans at some 22 percent, according to Zillow.com, it seems like this may be worth considering. (Find links to this report online at www.searchchicago.com/homes.)

Some economists are convinced that yet another wave of foreclosures is on the horizon. This time around, they say, it will not be underwater or subprime mortgage holders who default, it will be those with good credit, lots of home equity and affordable loans -- but no income.

"Job losses are a major reason once-safe borrowers are falling into trouble," reports Michael Brush, of MSN Money. "With unemployment likely to rise, the problem will only get worse."

He's basing his prediction on statistics, but anecdotally, that wave already has begun.

Internet sites are overflowing with the sad stories of homeowners whose income has dried up. They have high, enviable credit scores, nice homes with lots of equity, college degrees or professional experience. In the past year, they've laid off their employees, closed their shops and businesses, and now feel they are about to lose everything.

If you don't know anyone who has been affected by layoffs and decreased income, you're rare indeed. All around us are formerly two-income households getting by on one income, and one-income households now on unemployment.

Here's a good idea suggested by one anonymous blogger who was not whining and blaming one political party or another (and that is another rarity): Lenders could give a six-month grace period to those who have lost a job, and tack those six months on to the end of the mortgage. Or perhaps they could offer a temporary, interest-only loan modification, which might help those who are re-employed but living on a reduced income.

It doesn't hurt to have a newspaper on your side sometimes.

An elderly lady in Ald. Ed Burke's 14th ward couldn't get anyone to clean up the foreclosed home next door to her house on St. Louis Avenue. The yard was full of weeds and trash, she said, and she was afraid there might be rodents as well. She wrote me to say she had contacted Ald. Burke's office, Streets and San and 911 -- and no one did a thing.

I sent an e-mail to Burke's office, and at first heard nothing. But 10 days later I got a reply saying the whole lot had been mowed and cleaned. They sent me three photos as proof.

She contacted me again, very happy that the property had been cleaned up.

"I'll see if this is only a one-time thing," she wrote, "or if Burke will follow through on keeping this property up."

Kay Severinsen is editor of SearchChicago-Homes.