Confirmation Bias: Why Agreeing Evidence Feels Like Proof
A few agreeing examples can make an idea feel certain. Try a number puzzle that shows how you test your own hunches, learn why disconfirming evidence is so easy to skip, and practice giving a belief a fair test before you act on it. Five short chapters, eight quick checks, about fifteen minutes.
BySeph Fontane Pennock
Reviewed byMichael Callans, MSW
What is confirmation bias?
Confirmation bias is the tendency to favor information that supports what you already believe or expect when you seek or interpret evidence. You might collect reassuring examples, overlook awkward ones, or demand stronger proof from a finding you dislike. It can happen without a deliberate intention to be unfair.
Confirmation bias examples
- At work: believing a meeting format is faster, then remembering only the short meetings.
- In a garden: praising a new soil after looking only at healthy plants, while leaving struggling plants out of the comparison.
- In a conversation: interpreting a slow reply as annoyance while overlooking other plausible explanations.
A mistaken belief alone is not evidence of confirmation bias. Look at how someone searches for and weighs the evidence. Read Nickerson’s review of confirmation bias.
The study behind the number puzzle
In 1960, Peter Wason asked participants to discover a rule from the example 2, 4, 6 by proposing other triples and receiving feedback. Many settled on overly narrow rules and struggled to eliminate them, illustrating how repeated agreement can leave alternative explanations untested. Wason’s rule-discovery study.
20 for the experiment, 10 for each check. Retries earn full points.
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Questions about confirmation bias
What is confirmation bias in psychology?
Confirmation bias means favoring evidence that agrees with an existing belief or expectation when seeking or interpreting information. It concerns how evidence is handled, not simply whether the belief is right or wrong.
What is an example of confirmation bias?
Someone believes a new garden soil is better and records only the thriving plants, overlooking the struggling ones. The selective record supports the belief by leaving out relevant evidence.
Does the 2-4-6 task measure how biased I am?
No. This guided exercise illustrates hypothesis testing. Your choices, familiarity with the puzzle, and the instructions affect what happens. Your points reflect completed learning activities, not a psychological score.
How can I reduce confirmation bias in a decision?
State your idea, consider another explanation, and look for observations that would separate them. Decide in advance what would change your mind, and use the same standards for evidence you like and evidence you dislike. This is a useful practice, not a guarantee.
Sources
- Wason, P. C. (1960). On the failure to eliminate hypotheses in a conceptual task. Quarterly Journal of Experimental Psychology, 12(3), 129–140.
- Nickerson, R. S. (1998). Confirmation bias: A ubiquitous phenomenon in many guises. Review of General Psychology, 2(2), 175–220.
- Klayman, J., & Ha, Y.-W. (1987). Confirmation, disconfirmation, and information in hypothesis testing. Psychological Review, 94(2), 211–228.
Cite this source
Psychology.com. (2026, September 16). Confirmation Bias. Psychology.com. https://psychology.com/courses/confirmation-bias
More mini courses
- Anchoring Bias (12 to 15 minutes): Spin a random wheel, compare your estimate with its anchor, and practice using evidence to make better judgments.
- Hindsight Bias (12 to 15 minutes): Make five predictions, then compare your remembered answers with the record. Learn why a known ending can make uncertainty disappear.
- The Availability Heuristic (12 to 15 minutes): Compare your frequency estimates with real counts, distinguish recall from evidence, and practice a simple base-rate check.