Confirmation Bias

During the 2008 U.S. presidential election, Valdis Krebs at analyzed purchasing trends on Amazon. People who already supported Obama were the same people buying books which painted him in a positive light. People who already disliked Obama were the ones buying books painting him in a negative light. Just like with pundits, people weren’t buying books for the information, they were buying them for the confirmation.

Confirmation bias occurs when people actively seek out information which confirms their opinion and disregard information which contradicts it. They do this because it makes their world seem more comfortable and orderly.

Let's say you believe that your neighbour is an undercover cop. He comes in to his house only at night and has a dark tinted police type car. He is never seen outside his home. Let's say one day you see a lot of cars parked in front of his house one night. One of the cars is a police type car and you conclude that this guy