This month, in our continuing series on teaching clarity in thinking and reasoning, we tackle the common problem of “confirmation bias.” This is the tendency to overvalue evidence that supports a belief we already hold, while discounting evidence that contradicts or weakens support for our belief. This can help explain the widening chasm between political camps, where neither side is swayed by the evidence the other presents. Social media are awash in confirmation bias, where one-sided arguments are posted for the benefit of others who hold similar beliefs. This leads to “silos,” or “echo-chambers,” in which beliefs and their supporting evidence are repeated and reinforced. It appears that each side seems to believe that, given enough evidence, the other side will see the light and choose to believe the opposite view. This seems not to happen, hence the joke, “Number of Facebook users: 2.27 billion; number of minds changed: 0.”

Most philosophers would agree that the phrase “I’ll believe whatever I wish to believe” is misleading at best. The assumption that we can will ourselves to believe, should we simply choose to do so, seems unsupportable. Although we can voluntarily point ourselves to evidence in support of or against a belief, we don’t seem to be able to will ourselves to believe it.[1] The various facts and arguments that we believe make our case either fall on deaf ears or are re-interpreted to support an opposing view.[2]

It’s as though the adage, “seeing is believing,” is turned on its head: “believing is seeing.” And once we believe a claim, we tend to view all subsequent evidence through the lens of that belief, which serves to tailor or customize new facts to conform to our belief about them or to negate them to the extent that they do not conform. This is another way to understand confirmation bias.

Teaching provides an unusually rich environment for changing minds and, as a teacher, you are an authority figure who is more likely to be believed and emulated. You are therefore in a position to alert students to their own confirmation biases, and even to point out your own biases from time to time. Revealing these biases improves the possibility of better and more critical thinking. To learn more about confirmation bias, see these websites:

  • What is Confirmation Bias?In a short, easily digestible piece, Author Terry Heick defines confirmation bias, gives an example in the context of a teacher’s own job security, and identifies six steps to confirmation bias. These start with forming an opinion, finding data to support it, and so on, up to the sixth step, in which he suggests, you “…Continue to discount and discredit new or better data because then you’d have to reconstruct your belief system, apologize to people, admit you were wrong, etc.” As well, he offers six steps to correcting bias, including, Consider all data equally and know how to separate good data from bad, fact from opinion, misrepresented facts from properly-contextualized facts, etc.”
  • Confirmation Bias: A class activity adapted from Wason’s 2-4-6 Hypothesis Rule Discovery TaskA developmental psychology site offers a practical, if somewhat complicated, class activity that is used with philosophy and psychology students. According to Devpsy:“We actively try to support whatever we already believe rather than trying to find out how we might be wrong. We interpret ambiguous or mixed information to confirm our existing theories. This natural inclination in our thinking is called the confirmation bias. This class activity builds on Peter Cathcart Wason’s (1960) 2-4-6 Hypothesis Rule Discovery task to surprise students with how easily their thinking can be led astray.”
  • Teaching confirmation bias using The BeatlesProfessor John Minahan, an American psychologist, devised a clever and fun exercise for students based on the long-time claim that Paul McCartney is dead and was replaced by someone else since 1966. Dr. Minahan concludes, “We all engage in confirmation bias, which means we can all do something about it. ‘You say you want a revolution? The Beatles asked. ‘You better free your mind.’”
  • Lesson Plan: Can You Beat Cognitive Bias?Rachel Robertson, writing for KQED’s “The Lowdown,” presents a detailed lesson plan for teaching confirmation bias, including vocabulary, assignments and homework. She suggests these guides to discussing “who is responsible” for cognitive bias, “Ask: Whose fault is it when you can’t change someone’s mind? Is it that you aren’t being convincing enough or that the other person is too stubborn? Call on students to share what they think. • Explain: It’s no one’s fault! Getting someone to change their mind about a firmly held belief is hard to do. We all have cognitive biases. That means our brains are wired in ways that can limit our logical thinking and cause us to think in ways that don’t always make a lot of sense. This explains why people have a hard time changing their minds or do things like fall for crazy fake news stories.”
  • The Gorilla ExperimentYou may well have heard of this video/experiment, described here, “Imagine you are asked to watch a short video (above) in which six people-three in white shirts and three in black shirts-pass basketballs around. While you watch, you must keep a silent count of the number of passes made by the people in white shirts.” Although this is more a test of selective perception, it also helps us to understand how focusing on evidence in support of our own beliefs likely blinds us to at least some contrary evidence. In any case, for those who have not seen this, it can be quite stunning. If trying this with students, ensure those who know the video keep silent until all have seen it.

[1] For the philosophically inclined, see papers on the subject of “doxastic (in)voluntarism”: whether one can will oneself to believe.

[2] Some argue that the puffs of dust and debris being blown out of the windows of the World Trade Towers as they collapsed in 2001 prove that the building was brought down by carefully-placed and timed explosives. Others see the same evidence and argue that the windows on each floor are merely being blown out by the compression of the above floor(s) falling on them. Both arguers would likely say that “seeing is believing.”

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