I am using Don Ariely's book, Predictably Irrational, in a class. We recently finished his chapter, "The Effect of Expectations, Why the Mind Gets What it Wants." In the chapter he discussed the Coke-Pepsi taste tests, so one of my students decided we should do our own taste test.
All of us were given two cups, one with Coke and the other with Sam's Cola, the Wal-Mart brand, but we did not know which was which. Three out of five said that they preferred the cup that was actually Coke, but only two of five correctly identified the Coke sample. Two of them said that there clear differences, that the Coke was smoother and the Sam's Cola was sharper. The other three did not see much difference.
Ariely presents evidence that taste tests done when people know the brand turn out very different than when people do not know the brand. Expectations do affect our perceptions. "That is what marketing is all about--providing information that will heighten someone's anticipated and real pleasure."