From: https://www.verywell.com/what-is-a-confirmation-bias-2795024
Where do your beliefs and opinions come from? If you are like most people, you probably like to believe that your beliefs are the result of years of experience and objective analysis of the information you have available. The reality is that all of us are susceptible to a tricky problem known as a confirmation bias. While we like to imagine that our beliefs are rational, logical, and objective, the fact is that our ideas are often based on paying attention to the information that upholds our ideas and ignoring the information that challenges our existing beliefs.
A confirmation bias is a type of cognitive bias that involves favoring information that confirms previously existing beliefs or biases. For example, imagine that a person holds a belief that left-handed people are more creative than right-handed people. Whenever this person encounters a person that is both left-handed and creative, they place greater importance on this "evidence" supporting their already existing belief. This individual might even seek "proof" that further backs up this belief while discounting examples that do not support this idea.
Confirmation biases impact how people gather information, but they also influence how people interpret and recall information. For example, people who support or oppose a particular issue will not only seek information that supports their beliefs, they will also interpret news stories in a way that upholds their existing ideas and remember things in a way that also reinforces these attitudes.
Consider the debate over gun control. Sally is in support of gun control. She seeks out news stories and opinion pieces that reaffirm the need for limitations on gun ownership. When she hears stories about shootings in the media, she interprets them in a way that supports her existing beliefs.
Henry, on the other hand, is adamantly opposed to gun control. He seeks out news sources that are aligned with his position, and when he comes across news stories about shootings, he interprets them in a way that supports his current point of view.
A number of experiments conducted during the 1960s demonstrated that people have a tendency to seek information that confirms their existing beliefs. Unfortunately, this type of bias can prevent us from looking at situations objectively, can influence the decisions we make, and can lead to poor or faulty choices.
During an election season, for example, people tend to seek positive information that paints their favored candidates in a good light while looking for information that casts the opposing candidate in a negative light. By not seeking out objective facts, interpreting information in a way that only supports their existing beliefs, and only remembering details that uphold these beliefs, people often miss important information that might have otherwise influenced their decision on which candidate to support.