"Consider someone who buys an expensive car and later discovers that it is uncomfortable on long drives. Disagreement, or
dissonance, exists between their beliefs that they have bought a good car and that a good car should be comfortable.
dissonance could be reduced by deciding this discomfort does not matter since the car is mainly used for short trips (decreasing the importance of the dissonant evidence) or focusing on the car''s strengths such as safety, appearance, and handling (thereby adding more consonant evidence). The dissonance could also be eliminated by getting rid of the car, but this behavior is a lot harder than changing beliefs. Moreover, if ambiguous information about the car arrives (a friend comments "this looks like a really interesting car"), it is more likely to be interpreted as supporting the belief that the car is good ("the friend means the car looks really cool and unique") rather than countering it ("what is an interesting looking car? The friend must mean it looks like a real lemon. Maybe the fact it''s uncomfortable on long drives shows."). This example illustrates two cognitive biases that are consistently observed in agents making decisions under uncertainty: cognitive dissonance and confirmatory bias. Cognitive dissonance states that after having taken an action people tend to change their beliefs about the relative agreeableness of this action. Confirmatory bias refers to the phenomenon of people interpreting new evidence in ways that confirm their current beliefs. The abundant psychological literature on these two biases (overviewed in Section II) indicates that people behave as if they have a taste for: 1.
consistency between the action taken and the belief held at each point in the decision process and 2. consistency between beliefs in di¤erent stages of the decision process".