The confirmation bias applies to how we seek, interpret, and remember information. When we want to believe something, we tend to only seek evidence that confirms our desired belief and ignore the rest. When we do come across disconfirming evidence, we are more likely to dismiss the evidence and not critically evaluate it (Nickerson, 1998). If two people have the same information, the information is generally interpreted in such a way that supports one's existing beliefs (Lord, Ross, & Lepper, 1979). People who seek and interpret information critically and systematically, without bias, can still later recall the information selectively based on existing beliefs (Hamilton, 2005).
Example #1: Joe's friend told him that the moon landings were actually a Hollywood stunt and did not really happen. Joe was skeptical of this claim, and proceeded to Google "moon landing hoax." Google returned over half a million results with all kinds of pictures, testimonials, videos, and unedited recordings providing evidence of the fake moon landings. After a few hours, Joe was convinced that the moon landings were a hoax given the evidence he uncovered.
What Joe failed to do was follow one of the most important rules of critical thinking and scientific methodology—look for disconfirming evidence that would prove his hypothesis (i.e., that the moon landings were fake) incorrect. Googling "moon landing evidence" turns up over six and a half million results—including high quality primary sources such as NASA, as opposed to than "Billy Bob's Internet House of Conspiracy Theories."
Example #2: Joe told Susan about how the evidence for the moon landing hoax is "overwhelming." Susan asked him how he came to this conclusion, then proceeded to educate Joe about the confirmation bias and its likely role in Joe's "research." Joe, appreciating reason, admits that he might have only looked for confirming evidence. He then goes back and spends a few hours looking at the evidence for the moon landings and evidence that claims to debunk the conspiracy theorists' claims. Joe is not impressed. He still believes in the hoax theory, although less confident in his belief than before.
Joe, although appreciating reason, is still human. Joe is emotionally invested in the idea that the moon landing was a hoax because it would be, in Joe's words, "the greatest conspiracy of all time." Besides, he wants to be right and prove Susan wrong. These are unconscious thoughts so Joe does not realize that these thoughts have influenced how he evaluated the evidence.
Example #3:Susan asks Joe about his history with the moon landings, how much he remembers, and if he remembers any controversy. Joe was seventeen years old in 1969, and he remembers watching the event on television. He also remembers several discussions and events since that time when the legitimacy of the moon landings were brought into question. It turns out that Joe has always been very skeptical that we landed men on the moon.
Joe managed to recall conversations and events that provide "evidence" for the moon landings being a hoax, whereas he does not recall events that support the moon landings. All three forms of confirmation bias are working together forming a feedback loop that is making it very difficult for Joe to evaluate the evidence critically.