Look, for example, at this witty little experiment.
Baba Shiv, a neuroeconomist at Stanford, supplied a group of people with an energy drink that was supposed to make them feel more alert and energetic. The bottle promised its potent brew of sugar and caffeine imparts ‘superior functionality’).
Some paid full price for the drinks, others a discount, then asked to solve word puzzles. People who paid discounted prices solved far fewer puzzles than the people who paid full price. They were convinced that the stuff on sale was much less potent, even though all the drinks were identical.
Jonah Lehrer:
When you give people bottles of wine without any price information, there is no correlation between the cost of the wine and its subjective ratings. An $8 bottle is as enjoyable as an $80 bottle.