A confirmation bias is a type of cognitive bias in which people tend to seek out information which agrees with previously held beliefs. They also lend more weight to informational input which supports their beliefs, while discarding contradictory information. The confirmation bias is one of the most common cognitive biases, and it can also be the most dangerous, because it can lead people into very poor decisions on the basis of questionable information. Learning to recognize a confirmation bias is very important, and it is a good idea to utilize several techniques to avoid a confirmation bias, whether you care carrying out scientific research or buying produce.

There are a number of reasons why the confirmation bias is so strong. Like any cognitive bias, this bias is a shortcut in the brain to process information, but the shortcut has some shortcomings. The confirmation bias is probably related to a common human desire to be right, and to avoid embarrassment by recanting a previously held belief. A confirmation bias can also ensure that entrenched religious, ideological, and ethical beliefs are not challenged, thus making believers feel more confident.

There are some obvious dangers to the confirmation bias, of course. For example, in scientific research, scientists could skew the results of a study by only seeking out information which confirmed their hypothesis. In a study looking at the effects of the lunar cycle on human behavior, for example, a scientist might believe that humans engage in more dangerous behavior around the new moon, and the hypothesis might be tested by tracking emergency room admissions. If the scientists only looked at admissions from around the new moon, this would be a classic illustration of the confirmation bias.

A confirmation bias can also present a logic trap for people trying to engage in critical thinking. Many critical thinking classes encourage people to come up with views which are antithetical to their own opinions, to make people aware of the potential for a confirmation bias in critical thinking. In fields which require strong critical thinking skills, it is very important for people to constantly challenge their beliefs in an attempt to combat the confirmation bias, and people should also be unafraid of being wrong.

To avoid the confirmation bias in your own life, try to analyze your beliefs and ideas from a wider point of view. If you are testing a personal hypothesis, gather as much information as possible before determining whether or not the hypothesis is true; for example, if you believe that melons of a certain shape taste the best, collect a wide sample of melons of varying sizes and conduct a blind tasting test to confirm or refute your hypothesis. You also should not be afraid to play the devil's advocate in a discussion or argument, as this is another great way to defeat the confirmation bias.