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 type of cognitive bias and represents an error of inductive inference toward confirmation of the hypothesis under study.
Confirmation bias is a phenomenon wherein decision makers have been shown to actively seek out and assign more weight to evidence that confirms their hypothesis, and ignore or underweigh evidence that could disconfirm their hypothesis.
As such, it can be thought of as a form of selection bias in collecting evidence.
I encounter this most often when someone is displaying a condescending tone towards scientific evidence that is available with a simple Google search. These individuals will resist the simple act of pulling back a sheet covering an answer written in 10 foot letters that goes against their worldview. No matter how obviously wrong they are, these people prefer the ‘head in the sand’ approach over gathering simple information that would invalidate information that they hold to be true. In the psychological field of study, these people are revealed as to be at a greater predisposition to compulsive routines, blind faith and religious adherence. This is only a few of many reasons that this bias exists. Many people who lack the ability to examine and refute their own knowledge are very knee-jerk in opinion and comprise the extreme political views of both Right and Left. They lack the ability to take super charged emotion out of decision making and generally act first before weighing the consequences of their actions.