What is confirmation bias?
Confirmation bias is our tendency to seek out and accept evidence that supports what we already believe while ignoring or discounting evidence against it. Nickerson (1998) called it "a ubiquitous phenomenon in many guises," showing up everywhere from everyday life to science, law and medicine.
How does confirmation bias show up?
| Stage | What happens | Example |
|---|---|---|
| Searching | Looking only for supporting info | Googling phrases that assume your view |
| Interpreting | Reading ambiguous evidence your way | Two sides spinning the same statistic |
| Remembering | Recalling the hits, forgetting the misses | Remembering only dreams that "came true" |
In Wason's 2-4-6 task (1960), people trying to discover a number rule mostly tested sequences that would confirm their hunch rather than ones that could disprove it. Lord, Ross and Lepper (1979) gave supporters and opponents of the death penalty the same mixed research, and both sides came away more convinced of their original views—a pattern called attitude polarization.
Why does it matter, and how can you reduce it?
Confirmation bias leads to errors in investing, hiring, medical diagnosis and criminal investigations, and recommendation algorithms can amplify it into filter bubbles. For its role in fake news, see misinformation and confirmation bias; for the discomfort it helps us avoid, see cognitive dissonance theory. Common debiasing tips: deliberately look for disconfirming evidence, ask "What would I expect to see if I were wrong?", and assign someone to play devil's advocate before big decisions.
FAQ
- How is it different from cognitive dissonance?
- Cognitive dissonance is the discomfort of holding conflicting beliefs or actions; confirmation bias is an information habit that helps us avoid that discomfort. They often go together.
- How can I avoid it in a research paper?
- After forming a hypothesis, actively look for data that could contradict it, and report unfavorable results honestly as limitations.
Sources reviewed: 2026-10-25
References
- Nickerson, R. S. (1998). Confirmation bias: A ubiquitous phenomenon in many guises. Review of General Psychology, 2(2), 175–220.
- Wason, P. C. (1960). On the failure to eliminate hypotheses in a conceptual task. Quarterly Journal of Experimental Psychology, 12(3), 129–140.
- Lord, C. G., Ross, L., & Lepper, M. R. (1979). Biased assimilation and attitude polarization: The effects of prior theories on subsequently considered evidence. Journal of Personality and Social Psychology, 37(11), 2098–2109.