Confirmation Bias

“The seeking or interpreting of evidence in ways that are partial to existing beliefs, expectations, or a hypothesis in hand”

In other words, confirmation bias is the mental filtering of data to allow into one’s brain only that which confirms that which one already believes. Is this a sin for which you are guilty?

Anecdote, specious reasoning and the massaging of words into alien definitions are the hallmarks of pseudoscientists, religionists and politicians. With a little manipulation and constant repetition, just about anything appear to be the truth. This phenomenon was observed by psychologist John Mackay, who wrote about it in his landmark 1852 text, Extraordinary Popular Delusions and the Madness of Crowds.

“When men wish to construct or support a theory, how they torture facts into their service!”

Concepts and constructs are sometimes created innocently in attempts to describe a particular perception of reality. Take for instance such simple words as liberal and conservative. Others that come to mind are patriot, and hero. These are words in our language that are often misconstrued and abused. They are “hot button” words, which bring differing levels of emotion to the surface in individuals.

In this venue you have seen me torture words in an attempt to deconstruct some of the mythologies our society has built around otherwise simple constructs. Most recently, and only because the conservatives have all but captured the airwaves, I’ve taken to picking on those arguments. The conservative movement is part and parcel with the religious right, so I tend to pick at that part of the spectrum as well. Regardless, just because that side of the political spectrum is my current target does not give the other side a pass. A wingnut is a wingnut, regardless of side, and misspent verbiage is painful regardless of mouthpiece.

There is an obvious difference between impartially evaluating evidence in order to come to an unbiased conclusion and building a case to justify a conclusion already drawn. The scientist represents the first instance, in that science seeks evidence on all sides of a question, evaluates it objectively, and draws a conclusion based upon evidence. Religionists and politicians more often represent the second side of this equation. These folk, using predetermined criteria, gather and give unwarranted weight to only that evidence which supports the searcher’s position. This second phenomenon is called confirmation bias, and the searcher, although their action is purposeful, is often unaware of the action. There are, however, those who practice this with full knowledge and intent.

Purposeful confirmation bias is known as case building, and may be illustrated by what attorneys and politicians do. An attorney's job is to make a case for one side of a legal dispute. A prosecutor tries to gather and present evidence in support of the contention that a crime has been committed, while a defense attorney will present evidence supporting the presumption of innocence. Neither side has much to really win or lose, and neither is committed to an unbiased weighing of all the evidence at hand. Each is motivated only to confirm a particular position. Politicians also give undue attention to arguments that support their position. When a politician points to counterargument, it is only to point to weakness.

Confirmation bias connotes a less explicit process of case building. It refers usually to unwitting selectivity in the acquisition and use of evidence. The line between deliberate selectivity in the use of evidence and unwitting molding of facts to fit hypotheses or beliefs is a difficult one to draw in practice, but the distinction is meaningful conceptually, and confirmation bias has more to do with the latter than with the former. The assumption that people can and do engage in case-building unwittingly, without intending to treat evidence in a biased way or even being aware of doing so, is fundamental to the concept.

From The Onion comes this timely little piece, and the following video clip illustrates confirmation bias.



Over the past few days I have spent a great deal of time reading the various blogs as the various sides dissect President Obama’s SCOTUS nominee. In at least a few instances I’ve posted comments to offer some counter to an unreasonable argument. What I have found is that the most conservative of these blogs tend to filter, or moderate comments, and in two instances my comments were never posted.

I leave it to you, gentle reader, to determine just what this represents, and I would love to read your comments. My blog is uncensored and your message will go live as soon as you push the button, so speak your mind.

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