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Critical Thinking

This guide is designed to help learners improve critical thinking skills.

Confirmation Bias: What is it?

Encyclopaedia Britannica defines confirmation bias as, "the tendency to process information by looking for, or interpreting, information that is consistent with one’s existing beliefs".

Casad, B.J. (2019). Confirmation bias. Encyclopaedia Britannica. Retrieved July 23, 2020, 

Confirmation Bias: How to Avoid It

One way to avoid confirmation bias is to disprove what you believe instead of only looking for things that prove your belief.

Wason task
A problem-solving task developed by Peter Wason based on four cards, each of which has one class of stimuli printed on one side and another on the other side, and a rule governing the relationship between them. In the classic condition letters are on one side and numbers on the other and the rule is ‘vowels have even numbers’. Subjects get four cards with stimuli like H, A, 9, 4 showing and have to select two cards to turn over to make sure the rule has been followed. Subjects typically display a CONFIRMATION BIAS (picking ‘A’ and ‘4’ or ‘H’ and ‘9’), failing to realize that the only sure test of the rule is to check for possible disconfirming cases (picking ‘A’ and ‘9’ or ‘H’ and ‘4’). Also called the four-card problem.

Watch the video below to see the Wason Task in action.