Calling someone an optimist these days may be the polite way to say he's a sap. Optimism often occupies a second-class compartment in the train of human values, and is derided as a naive, soft-soap disposition that distorts the realities of life.

Yet, in the palette of human temperament, a rose-colored view of the future is the dominant hue, regardless of culture or nationality. Psychologists puzzle over this basic bias for the bright side. This sense of hope boosts consumer confidence, creates market bubbles and spurs irrational exuberance. "We don't know whether optimistic people are dumber or better than pessimistic people," said Martin Seligman at the University of Pennsylvania, who helped pioneer the study of positive psychology.

Two research teams exploring the anatomy of expectations offer a new perspective on the power of a positive outlook. For the first time, scientists at New York University have mapped the upbeat brain -- finding in a cluster of neurons the size of a martini olive the seed of a sunny outlook on life. At its core, the brain is built for optimism, their work suggests.

Far from deforming our view of the future, this penchant for life's silver lining shapes our decisions about family, health, work and finances in surprisingly prudent ways, concluded economists at Duke University in a new study published in the Journal of Financial Economics. "Economists have focused on optimism as a miscalibration, as a distorted view of the future," said Duke finance scholar David T. Robinson. "A little bit of optimism is associated with a lot of positive economic choices."

To detect its influence, the Duke researchers analyzed the U.S. Federal Reserve Board's Survey of Consumer Finances, a national balance sheet of what Americans own -- from houses and cars to stocks and bonds -- how much we borrow and how we bank. Normally, the triennial survey is used to frame discussions of tax policy, consumer debt and pension reform. The researchers used its data on personal predictions of life expectancy to sort the nation's optimists from its pessimists.