From The New York Times:
Sheena Iyengar is the psychologist responsible for the famous jam experiment. You may have heard about it: At a luxury food store in Menlo Park, researchers set up a table offering samples of jam. Sometimes, there were six different flavors to choose from. At other times, there were 24. (In both cases, popular flavors like strawberry were left out.) Shoppers were more likely to stop by the table with more flavors. But after the taste test, those who chose from the smaller number were 10 times more likely to actually buy jam: 30 percent versus 3 percent. Having too many options, it seems, made it harder to settle on a single selection.
Wherever she goes, people tell Iyengar about her own experiment. The head of Fidelity Research explained it to her, as did a McKinsey & Company executive and a random woman sitting next to her on a plane. A colleague told her he had heard Rush Limbaugh denounce it on the radio. That rant was probably a reaction to Barry Schwartz, the author of “The Paradox of Choice” (2004), who often cites the jam study in antimarket polemics lamenting the abundance of consumer choice. In Schwartz’s ideal world, stores wouldn’t offer such ridiculous, brain-taxing plenitude. Who needs two dozen types of jam?