In side-by-side taste tests, pub-goers agree: “MIT Brew” tastes better than Budweiser — as long as tasters don’t learn beforehand that the secret ingredient is balsamic vinegar.

It sounds more like a fraternity prank than a psychology experiment, but the beer-guzzling participants in a recent study were doing their part for psychology. In this case, helping researchers determine just what it is about consumers’ knowledge of food products that af-fects their taste judgments.

Leonard Lee, Columbia Business School, Shane Frederick, MIT, and Dan Ariely, MIT, were not surprised that foreknowledge of the unappetizing secret ingredient in their special brew might bias tasters against it. Marketers have long known that what consumers know about a product affects how they judge it. What the researchers didn’t expect to find was that learning the secret ingredient didn’t signifi-cantly affect participants’ taste judgments if they learned what it was after they had already sipped (but prior to rendering their judgment).

In “Try It, You’ll Like It: The Influence of Expectation, Consumption, and Revelation on Preferences for Beer,” published in the December 2006 issue of Psychological Science, Lee and his coauthors describe the experiment design: At two Cambridge, MA, pubs, nearly 400 patrons willing to lend their taste buds to science were randomly assigned to three groups. In each of three similar experiments, a “blind” group tasted and judged the two beers without knowledge of MIT Brew’s secret ingredient; an “after” group tasted the two beers and subsequently learned what was in MIT Brew before judging (Experiment 1) or before choosing which one they would want a full 10-oz glass of (Experiments 2 and 3); and a “before” group was told the difference between the two beers prior to tasting them. In Experiment 3, the “before” and “after” groups actually mixed their reward brew themselves (if they chose the MIT version).

Read the full article at psychologicalscience.org.