The stock market and investor nerves are under pressure. The turmoil in Greece and the rest of Europe is stoking investor fears of a Lehman-type global credit crisis and the prospect of a double-dip recession in the United States.

So, now is a good time to talk about music and wine. No, this isn't a tale of romance. Instead, it's about the risks and rewards of investing. Michael Mauboussin is the author of "Think Twice: Harnessing the Power of Counterintuition.'' Mauboussin is an intellectually omnivorous author who is also chief investment strategist at Legg Mason Capital Management and an adjunct professor at Columbia University's school of business.

He draws investing insights from a wide range of disciplines, from cognitive science to fractal mathematics to the mating habits of guppies. However, this story taken from his book comes from marketing research.

Imagine you're strolling down a grocery store aisle. There is a bin with French wine and next to it a basket of German wines. Sometimes the market researchers played French music and at other times the background music was German. It turns out that consumers bought French wine 77 percent of the time when French music was playing. But when German music was audible 73 percent of the buyers chose a German wine. Yet a majority of customers in follow-up interviews conducted by the researchers denied that the music influenced their choice.

What does this have to do with the markets and investing? Well, up until about a month ago it seemed that everything was looking up with the economy and markets. The stock market was up almost 80 percent from its March 2009 lows. Consumer spending had improved several months in a row, the manufacturing sector was doing better, and even hiring was starting to pick up for the first time in three years. Investor money flowed into stocks. Think upbeat French classical music.

I asked Fred Child, the wonderful host of American Public Media's classical music show "Performance Today," for some music suggestions. He recommended putting on Camille Saint-Saëns' "Carnival of the Animals," especially the last movement. You could also try Maurice Ravel's Piano Concerto in G Major.

But now the economic environment is scary. The widely followed equity-market "fear gauge" -- the Chicago Board Options Exchange SPX Volatility Index (VIX) -- is up sharply. The VIX measures the expected volatility of the Standard & Poor's 500 index. When the VIX number is high, investors are fearful; when it's low, confidence reigns. The index fell to a recent low of 15.58 on April 12. But with equities rattled by the recent troubles in Europe, as well as the disturbing rise in computer-generated trading, the VIX soared to a recent high of 45.79 on May 20 and hovered around 30 late last week.

Severe and dour German music could be playing, perhaps the beginning of Beethoven's Symphony No. 5 or maybe Beethoven's Piano Concerto No. 3, the 1st movement.

Here's the thing: The lure of jumping into the market when the news is positive is powerful, and the urge to run when it seems another cataclysm looms also is strong. But it usually doesn't pay to listen to the siren song of the market.

Don't let a bad stock market, or a good one, influence your investing decisions. Basically, for most individual investors it pays to stick with a long-term perspective and steer clear of Mr. Market's manic moods. Be very aware of the investing music in the background, influencing our perceptions.

How do you do that? Focus on your family and household, their needs and goals. What happens to your standard of living if the stock markets swoons again? Do college tuition bills loom? Is retirement just around the corner? These are kinds of questions that matter and will help you figure how much or little to have exposed to the stock market.

Oh, and have a glass of wine while you're thinking it over.

Chris Farrell is economics editor for American Public Media's "Marketplace Money." Send questions to cfarrell@mpr.org.