Feeling down or disgusted? Wait, don't buy or sell anything. And whatever you do, stay away from eBay or other online shopping sites until you cheer up.

That's because people tend to pay considerably more for an item when they're sad, claims psychologist Jennifer S. Lerner of Carnegie Mellon University. At the same time, she asserts, feelings of disgust can lead people to sell things at a lower price than they would otherwise.

It's not easy to simulate such real-world emotions and economic decisions, but here's the two-part process that Lerner and two Carnegie Mellon colleagues, Deborah A. Small and George Loewenstein, developed to do just that:

First, they asked 199 study participants (119 men and 80 women, most of them Carnegie Mellon students) to watch one of three movie clips. Test subjects sat alone at computer screens, and recorded their emotional states before, during and after viewing a four-minute segment.

A third of the sample watched a surrealistic scene from the movie "Trainspotting," which featured a longtime heroin addict's attempt to quit cold turkey and his dive into a filthy toilet to retrieve his "final hit" -- two opium suppositories. Yeew, that's disgusting, we agree.

A third saw a clip from the 1979 weeper "The Champ," in which a plucky towheaded lad faces the death of his well-meaning but sad-sack father. That was a downer.

A control group viewed a "neutral" clip -- tropical fish from a National Geographic film on the Great Barrier Reef.

Then, Lerner and her team asked the moviegoers to act as consumers. The researchers had already randomly assigned the study subjects to two groups. Members of one group were given a set of highlighter pens to keep, and then offered the opportunity to sell it. Members of the second group were not given the highlighters to start out; instead, they were shown the pens and asked to set a price they would be willing to pay to buy them. The participants then actually kept, sold or bought the highlighters, depending on the choices available to their group.

Each movie clip had the expected effect on its viewers, Lerner and her team found after reviewing the participants' written reactions. The dirty dive scene produced disgust, "The Champ" triggered sadness and the pretty fish produced no emotional reaction.

Then Lerner and her team analyzed the price data and found strong confirmation for what psychologists call the "endowment effect" -- the well-documented tendency of sellers to value objects more than buyers do. The participants who viewed the emotionally neutral fish scenes were willing to sell the highlighter set for an average of $4.58, or a dollar more than buyers were willing to pay for it. Interesting, but no surprise.

What did surprise her, Lerner said, was the effect that the two emotion-producing clips had on buying and selling decisions. For example, feelings of disgust entirely wiped out the endowment effect: Buyers and sellers both valued the pens at slightly under $3, Lerner and her colleagues reported in the latest issue of Psychological Science.

And for the sad group, the endowment effect was turned upside down -- the buyers were willing to pay far more for the pens (also $4.58, on average) than sellers were willing to sell them for ($3.06).

What's going on here? In Lerner's view, sadness sparks a need to change and expand our world; in this case, that translates into a desire to buy stuff. That's why people who shop or do other business online should think twice before getting on the computer when they're feeling sad, she said.

In contrast, disgust makes us want "to expel what we have" rather than acquire things, she asserted.

Lerner added that the huge impact of sad feelings occurred even though the researchers concluded that "The Champ" was a bit of a chump when it came to triggering the intended emotional response.

"The movie's too dated," Lerner said. "It produced a very mild level of sadness. It amazed us that we still got such a sizable effect; the effect should be much stronger in the real world."

Dear Newlywed . . .

So you're going to be a June bride or groom? That's so sweet! The Unconventional Wiz has some advice: If you're a "people person," feel free to be optimistic about married life. Those positive expectations will help make your dreams of a happy marriage more likely to come true.

For those of you who aren't so good with people, don't worry. You can achieve marital happiness, too -- all you have to do is expect the worst and, ultimately, you will be happier and more satisfied with your marriage than if you had high expectations, assert two psychologists who tracked marital satisfaction among 82 newlywed couples over their first four years of marriage.

James K. McNulty of Ohio State University and Benjamin R. Karney of the University of Florida found that outgoing people who had the "ability to behave constructively" were most satisfied with their marriages if they had high expectations about married life.

This suggested to the researchers that those newlyweds use their "people skills" to solve problems and take steps to improve their relationship.

But for newlyweds who lacked people skills, modest expectations were best -- because that way, they were less likely to be disappointed when their spouses turned out to be less than perfect, McNulty and Karney wrote in the latest issue of the Journal of Personality and Social Psychology.

The New

Vast Wasteland

Well, first the good news: Teenage boys may be watching less television. The bad news: They're spending more of their time playing video games, says a researcher whose company monitors media usage.

Robert DeFelice of Knowledge Networks/SRI said its survey of how Americans spend their time found that video games have emerged as the fourth most dominant media among men, firmly displacing print (gulp!), and rivaling the major electronic media for the attention of twentysomethings and teenage boys.

Teenage males (ages 12 to 17) are the most devoted to gaming, the survey of 5,000 adults and teens found. Video games occupy about 15 percent of the time that teenage boys spend with any form of media. That's nearly as much time as they spend listening to the radio (17 percent) or on the Internet (16 percent), and far more than they spend with newspapers (3 percent) or magazines (3 percent).

Television still claims the largest share of these teenagers' attention -- 45 percent of their media time. But TV execs, watch out: The apparent devotion to video games may be responsible for the drop in TV viewership among young men, suggests MediaPost, an Internet Web site that serves companies seeking to buy advertising in various media.

morinr@washpost.com