Real estate agents say you should buy the worst house in the toniest neighbourhood rather than the best house on a modest street.

But Daniel Gilbert, a Harvard University psychology professor, believes such a purchase is rarely a prescription for happiness. Before you sign that offer to purchase, consider how you'll feel coming home each day to a dump amidst the mansions.

"It will make you feel bad because the brain is a difference detector; almost everything that it senses, it senses as a comparison," he says in Toronto to talk about his book Stumbling on Happiness.

The capacity to imagine future happiness or unhappiness — called "affective forecasting" — is, Gilbert says, what distinguishes us from other animals.

As he puts it, "We don't have to actually have gall bladder surgery or lounge around on a Caribbean beach to know that one of these is better than another."

Gilbert has spent 15 years at Harvard's Social Cognition and Emotion laboratory investigating how people imagine what will make them happy, and why they so often get it wrong.

He has found that small pleasures like coming home to a house no worse than the neighbour's is more likely to yield long-term joy than inheriting $1 million, getting a big promotion or being elected president.

"It's the frequency and not the intensity of positive events in your life that leads to happiness, like comfortable shoes or single malt scotch," he says.

Gilbert's happiness level increased when he was hired by Harvard, not because of the prestige but because he could walk to work. Cargo pants also make him happy; he likes to buy them five or six at a time, though he wore a black sports jacket and well-tailored black trousers for our interview in the office of his publisher, Knopf Canada.

Although we humans have the capacity to imagine what will make us happy lodged in our well-developed frontal lobes, we are not good at it. It's the way we consistently err that fascinates the professor.

His researchers at Harvard interviewed voters before and after recent U.S. elections who said they would be extremely unhappy if George W. Bush won and would likely move to Canada — but who reported after the vote that they feel just fine.

"In prospect it always seems so dire," he says.

The Harvard researchers have also done extensive interviews with sports fans who just know they'll never smile again if their team loses but, of course, recover speedily after a loss.

"The human brain mispredicts the sources of its own satisfaction," Gilbert says, "and the reason is that we fail to understand how quickly we will adapt to both positive and negative events. People are consistently surprised by how quickly the abnormal becomes normal, the extraordinary becomes ordinary. When people say I could never get used to that, they are almost always wrong."

Gilbert believes we have an emotional immune system that helps us regain our equilibrium after catastrophic events.

`I am not saying that losing a leg won't change you in profound ways. But it won't lower your day-to-day happiness in the long run'

"The studies of Holocaust survivors are clear — most went on to lead happy and productive lives," he says.

He also cites extensive research to show that disabled people and those who have had cancer are just as likely to report that they are happy as the able-bodied and healthy.

"I am not saying that losing a leg won't change you in profound ways. But it won't lower your day-to-day happiness in the long run."

Gilbert is not working in a vacuum. He is one of a growing number of scholars engaged in the relatively new field of happiness studies, an interdisciplinary area comprising psychologists, neuroscientists, philosophers and economists.

At Harvard, economists Max Bazerman, Sendhil Mullainathan and David Laibson are notable in the field. A behavioural economist, Laibson is an expert on retirement-savings plans who studies why people tend to devalue the future in favour of present gratification.

At Princeton, Daniel Kahneman has co-written a standard work, Well-Being: The Foundations of Hedonic Psychology.

Ed Diener at the University of Illinois at Urbana-Champagne is studying the relationship of income to happiness.

Launched in 2000, there is even a peer-reviewed Journal of Happiness Studies, of which Diener is co-editor.

While some see it as a soft subject, understanding happiness may be extremely relevant today, says moral philosopher Sissela Bok, due to a worldwide rise in living and health standards and a drop in birth rates and infant mortality. More people expect to be happy.

In Canada, University of British Columbia economist John Helliwell is the country's leading figure in happiness studies. Helliwell, whose book Globalization and Well-Being won the Donner Prize in 2003, has studied the happiness that comes from social affiliation and its relationship to productivity.

One of the problems in happiness studies is how to measure outcomes. You can't build a science on something that can't be measured. Gilbert, however, says that self-reporting, the method used by his lab, is perfectly reliable.

"We just ask people how they feel right now. The eye doctor relies on you telling him what you see. Vision, like happiness, is subjective, yet they have built a whole science of optometry on this."

Is there a better way to predict what will make us happy than using our imagination?

"Yes," he says, "but no one wants to use it. It's called surrugation, and it circumvents biases and errors. If you want to know how happy you'll be if you win the lottery, ask a lottery winner — it's a mixed blessing. Will having children make you happy? Observe people who have them."

People discount this approach because of what Gilbert calls "the myth of fingerprints."

"Most of us have the illusion of uniqueness," he says. "We believe that other people's reactions won't tell us about our likes and dislikes. But we are remarkably similar. We share the same biology, and others' experiences can teach us a great deal about our own.

"As long as we maintain our illusions about our uniqueness, we will continue to ignore information that's in front of our noses."