Cornell University researcher Brian Wanskin arranged to give diners at a prix-fixe restaurant a complimentary glass of wine. The diners were shown the bottle before the wine was poured into their glass. Some of the diners were shown a wine bottle apparently from a fancy California winery called "Noah's Winery." Others were shown a bottle from a North Dakota winery. But in all cases the wine they were served was actually the same. It was a cheap Charles Shaw Cabernet (familiar to Trader Joes shoppers as "two-buck chuck").
Predictably, the diners seemed to appreciate the wine and their meal more when told that they were drinking a high-class California wine, as measured by how long they lingered at the table and how much food they ate.
Wanskin concludes that, "Within limits, a food expected to taste good will taste good, and a food expected to taste bad will taste bad."
My theory with wine has always been that while there may be a noticeable difference between a $2 and a $15 bottle of wine, once you get over $15, there's really no appreciable improvement. People just expect very expensive wine to taste better, so they convince themselves that it does taste better. (via New Scientist blog)