It’s well known that people suffer from confirmatory bias, so after they buy a new car they eagerly read the advertisements for that car – the ads, of course, confirm that their purchase was a good one.
Many people also have a predecisional bias, they interpret new information in a way that is biased towards the leading candidate – a confirmation bias in expectation. In Choosing an Inferior Alternative (also here) Russo, Carlson and Meloy show that careful manipulation to take advantage of predecisional bias can actually cause people to choose inferior alternatives.
The authors ask people to rate restaurants, nominally named A,B,C etc., on a series of attributes (atmosphere, hours, parking, dishes and so forth) thus creating a ranking. Two weeks later they ask the same people to rate the same (but renamed) restaurants in a series of pairs. But this time they put the attribute that most favored the inferior restaurant first – thus the inferior restaurant would win the first comparision and further attributes would suffer from predecisional bias. They also put the attribute that had the second strongest favorable rating for the inferior restaurant last to take advantage of any recency effect. The least favored attributes were buried in the middle.
Compared to a control group, twenty percent more of the treatment group chose an alternative that according to their own preferences was inferior. In fact, in the treatment group a majority chose the inferior alternative.