Most people tend to look for information and collect evidence to support a pre-existing viewpoint. We actively seek and attach greater importance to information that supports our hypothesis, while ignoring any evidence that refutes it. Simply put, once we have formed an opinion, knowingly or not, we're unlikely to be objective in gathering information. This tendency is caused by the desire of our brain to find the shortest path to process information efficiently and practically. This makes sense in the modern world, where information is limitless, and the time for making decisions is limited.
British psychologist Peter Vason coined the term in the 1960s. Around the same time, experiments showed that people are prone to validating existing beliefs. Later research has reformulated this phenomenon as a tendency to test hypotheses in a one-way way, focusing on one outcome and ignoring others.
An interesting historical example is Abraham Lincoln, who deliberately filled his government with rival politicians with opposing ideologies. To avoid confirmation bias, of course.
Confirmation bias stems from the existence of cognitive dissonance in human nature. This is the state we experience when two conflicting beliefs are simultaneously held in the brain. There are two main cognitive mechanisms through which we express this principle:
Because confirmation bias is a shortcut for the brain, it allows investors to make quick decisions. Investors, as a rule, when evaluating information, ask questions in such a way that only an affirmative answer is possible, thus the opposite data is often overlooked, intentionally or otherwise.
Regardless of the evidence presented, if we are unaware of what is happening, we are more likely to interpret the data in a way that supports our point of view. Fortunately, once you acknowledge this contradiction, several strategies can help keep your confirmation bias in check.