In psychology and cognitive science, confirmation bias (or confirmatory bias) is a tendency to search for or interpret information in a way that confirms one's preconceptions, leading to statistical errors. Confirmation bias is a phenomenon where decision makers have been shown to actively seek out and assign more weight to evidence that confirms their hypothesis, and ignore or under-weigh evidence that could disprove their hypothesis.
Bias occurs from the direct influence of desire on beliefs. When people would like a certain idea or concept to be true, they end up believing it to be true. They are motivated by wishful thinking. This leads the individual to stop gathering information when the evidence gathered so far confirms the views or prejudices one would like to be true.
According to a University of Iowa study last year once people reach a conclusion, they aren’t likely to change their minds, even when new information shows their initial belief is likely wrong and clinging to that belief costs real money.
The study was to help in the understanding financial markets. In the study student traders bought and sold real-money contracts to predict the four-week opening box office receipts for a new movie. The research showed that even as the key first weekend box office receipts were reported, prices stayed remarkably stable as traders ignored new value-relevant information and continued to rely on their initial estimates.
Once we have formed a view, we believe information that confirms our view and ignore, or reject, information that casts doubt on it. Confirmation bias suggests that we don’t perceive circumstances objectively. We pick out those bits of data that make us feel good because they confirm our prejudices.
Confirmation bias can also be found in anxious individuals, who view the world as dangerous. For example, a person with low self-esteem is highly sensitive to being ignored by other people, and they constantly monitor for signs that people might not like them.
Wishful thinking is a form of self-deception where confirmation bias is at play. It is the formation of beliefs and making decisions according to what might be pleasing instead of by examining evidence, thinking rationally, or what is shown by reality. Wishful thinking is used to resolve conflicts between belief and desire.
Studies have shown that subjects will predict positive outcomes to be more likely than negative outcomes. However, research suggests that under certain circumstances, such as when threat increases, a reverse phenomenon occurs. Some psychologists believe that positive thinking is able to positively influence behavior and so bring about better results. This is called "Pygmalion effect".
Self-deception can be like a drug that numbs people from the harsh reality, but in some cases self-deception is good for us. For example, for dealing with certain illnesses having positive thinking may actually be beneficial because there is some evidence that believing that you will recover help reduce the level of stress hormones, giving the immune system and modern medicine a better chance to do their work.
In sum, people are prone to believe what they want to believe. Seeking to confirm our beliefs comes naturally, while it feels strong and counter-intuitive to look for evidence that contradicts our beliefs. This explains why some opinions survive and spread.
It's conformation bias that explains a lot that we saw during the recent U.S. presidential elections. People tend to seek positive information that paints their candidate in a good light while looking for information that casts the opposing candidate in a negative light.
By not seeking out objective facts and by interpreting information in a way that only supports their beliefs and remembering details that uphold these beliefs, people often miss important information that might have otherwise influenced their decision on which candidate to support.
It also explains a lot of "-ist" comments we see, especially these days on social media...racist, sexist, etc. and why some people are so willing to believe and post "news stories" that are unsubstantiated or outright fake.