What’s in a wine glass? Figuring that out can be tricky, even embarrassing, for casual tasters and experts alike. A legendary wine master, the late Harry Waugh, was once asked when he’d last confused a wine from Bordeaux for one from Burgundy. “Not since lunchtime,” he said.

Winedom is laced with anecdotes about how easy it is to err in guessing the origin of a wine (e.g., “I was sure this silky red was from Volnay, but the label says New Zealand!”). And based on the results of several recent experiments, it turns out to be as tricky to distinguish between cheap and expensive wines as it is to pinpoint their origin — as Harry Waugh surely could have warned us. Quite often, in fact, tasters preferred the plonk over the expensive stuff. And that raises the question: Should we spring for the expensive labels or settle for box wine?

In the most recent of these experiments, British psychologist Richard Wiseman asked 578 visitors to the Edinburgh Science Fair to taste eight pairs of wine, evenly divided between red and white. In each pair, one wine cost significantly more than the other. Yet, overall, the tasters correctly identified the wines by price barely half the time — in effect, a random outcome. They did best with a pair of pinot grigios, priced respectively at $6.50 and $14.25, identifying the more expensive bottle 59% of the time. They fared worst with red Bordeaux, correctly nailing the pricier pour only 39% of the time. Yet the price gap between these two wines was the most extreme among the pairings: $5.70 for the cheapo bottle versus $24.50 for the higher-end version. That outcome must have been embarrassing to the Brits, who practically invented the Bordeaux wine trade. But not as embarrassing as what happened to a Bordeaux winemaker who told me of a blind tasting in which he failed to identify his own wine.

The confounding message of Wiseman’s survey is that you may pay more for wine, but enjoy it less. In the US, that view is bolstered by a survey of more than 6,000 blind tastings published in 2008 by the American Association of Wine Economists. Summing up the results, lead researcher Evan Goldstein wrote, “Our main finding is that individuals who are unaware of price do not, on average, derive more enjoyment from more expensive wine. In fact, unless they are experts, they enjoy more expensive wine slightly less.”

In yet another 2008 experiment, a team of neuroeconomists at the California Institute of Technology found that 20 volunteers did no better at wine identification than Wiseman’s or Goldstein’s cohorts. The difference here was that the researchers did not rely only on the stated preferences of the participants. They also monitored their brain activity during tasting — specifically, in the medial orbitofrontal cortex, the region of the brain believed to register pleasure. This was done while having the participants sip controlled doses of each wine while lying in a magnetic resonance imaging machine.

The subjects were asked to taste five differently priced cabernet sauvignons, then rate them for “pleasantness and intensity” on a six point scale. As each wine was tasted, it was identified by its price: $5, $10, $35, $45 and $90 per bottle. Armed with that knowledge, the tasters gave their lowest ratings to the $5 and $10 wines. Their highest rating went to the $45 and $90 wines. This result diverged from the outcome of Wiseman’s and Goldstein’s experiments — or so it seemed.

But the volunteers had been tricked. They had been offered only three different wines, not five. The $5 wine doubled as the $45 wine, while the $10 wine also played the role of the $90 wine. Yet none of 20 subjects deduced that they were tasting only three wines. And, strikingly, the pleasure part of their brain, as monitored by the MRI, showed maximum activity when the supposedly most expensive wines were sipped and minimum activity for the lowest-priced wines. Price alone was influencing pleasure.

Tellingly, when the Caltech volunteers were later retested, this time without being told the prices of the wines being tasted, they preferred the least expensive wines.

Place, as well as price, can have an impact on tasters, according to a 2007 study published in the journal Physiology & Behavior. In that experiment, 39 diners at an Illinois restaurant were offered a complimentary glass of wine with their dinner. Half were told that the wine was from a California winery, while the other half were told that it came from North Dakota (the last state to host a commercial winery). In fact, both wines were identical: an inexpensive California red. All diners were served the same prix fixe meal, and when they were finished, their leftovers were weighed. Those who thought they were drinking California wine had eaten 12% more of their meal than those who thought they were drinking from North Dakota. The California drinkers also stayed longer at their tables.

Even servers at a wine-savvy restaurant can be befuddled. One morning last spring, the wine director of Union Square Café, Braithe Tidwell, assembled the staff for a tasting of what she told them was a rare and special wine: Chateau Rayas 1988, a $600 bottle from Chateauneuf-du-Pape in the Rhone Valley. But this being April Fool’s Day, the wine was actually a humble Gigondas, Chateau Redortier 2004, priced at $74.

Tidwell expected that her bluff would be called. But, although there were perplexed looks, “nobody came right out and said, ‘I don’t think this is right,’ ” she says.

For good reason, sommeliers aren’t likely to be sympathetic to blind tasting experiments in which cheap wines triumph over expensive vintages. After all, if they can’t believe in a hierarchy of wines, with the top tier priced at hundreds or even thousands of dollars, how they can convince diners to buy them?

“All kinds of things are wrong with those studies,” says Belinda Chang, wine director of The Modern, where she oversees a “1,600-plus” selection wine list. “A wine might not taste the same in a diner as in a five star restaurant. It will taste different depending on whether you drink it from a gorgeous Riedel hand-blown glass or from a tumbler. You might hate your date or be totally head over heels in love. All those factors impact the flavor of your wine.”

So it’s a little shocking — and somewhat refreshing — to talk to ex-sommelier Joshua Wesson, co-founder of the low-priced Best Cellars wine shops, who agrees with the scientists, that “there is no direct relationship between the price you pay and the pleasure you receive from a well-made bottle of wine.”

Wesson conducted his own blind tasting at Taste of Vail, a Colorado food and wine festival, a few weeks ago. He asked just over 100 volunteers, many with deep wine knowledge, to taste eight wines that were priced in $10 increments between $10 and $80 dollars. All had been “highly rated” by at least two credible sources. The tasters were given 20 minutes to ponder the wines, then put them in the proper price order based on how they tasted.

“The best anyone did was to get four out of eight wines in the correct order of price,” Wesson says. “The average was two out of eight. And a master sommelier from a local restaurant got zero right.”

The result, Wesson says, shows that “when tasters are left to their own devices, and have to struggle with their tongues, it’s a random walk.” And yet he is upbeat about that. “Once people are severed from this assumption that there is an automatic connection between pleasure and price, they become relaxed. They understand that all that matters is the pleasure you receive. In that sense, the smartest people in the room were those who got zero right out of eight.”

Perhaps the key is that, as with art, it’s not so much about price as it is about context. As Tim Gaiser, education director of the Court of Master Sommeliers, says, “The three variables in wine are the person, the wine itself, and the context. And context is huge.”

In the context of a wicker picnic basket to be opened on the beach, an inexpensive, fruity wine is all that you need, all that you may want. In the context of a special dinner, perhaps marking a big birthday, ordering an expensive bottle of wine may bring you more pleasure simply by splurging. When it comes to wine, your head may matter more than your taste buds.

Last summer, in Epernay, France, I was lucky enough to be at a table where the cork was popped on a bottle of Pol Roger Champagne, vintage 1914. It had come directly out of the winery cellar beneath us. No men had harvested or made that Champagne, because, as World War I erupted that late summer, they were all at the front. So the women and children harvested the grapes and made the wine that year, even as the sky was lit up by German artillery. “They could have cried and done nothing,” I was told, “but people did what they had to do. They just did it. Full stop.”

Still lightly sparkling and seemingly weightless, that almost century-old Champagne was described as evoking “starfruit, with a touch of candied grapefruit peel.” But that wasn’t the point. What mattered was context. That this was, as the French say, a “vin d’emotion.” In a blind tasting, I’d guess that this faded but still beautiful relic would hardly have been noticed, and no MRI scan could have decoded its specialness. In real life, there were tears.

Peter Hellman wrote the Urban Vintage column for the New York Sun and contributes frequently on wine for The Wall Street Journal and Wine Spectator.