Science · Mind

What Is Confirmation Bias?

Why we notice what fits, and forget what does not.

The question

Why is it so hard to see evidence against what we already believe?

The short answer

People tend to search for, interpret and remember information in ways that confirm what they already think. It is one of the best-documented findings in psychology.

Once you expect a face, you find one. Expectation shapes what the eye picks out.

What science knows

Established Science

In Peter Wason’s 1960 “2-4-6” task, people guessing a number rule mostly tested examples that fit their idea, rarely ones that could rule it out.

In a 1979 study, people on both sides of the capital punishment debate read the same mixed evidence and each came away more convinced of their own view.

The pattern

Established Science

The bias works at three stages: what we look for, how we interpret it, and what we remember. Hits are vivid and counted; misses are quietly dropped.

What is still uncertain

Mixed Evidence

Techniques such as deliberately considering the opposite can reduce the bias, but effects in studies are often modest and may not last. Some researchers argue the bias is partly a reasonable strategy when evidence is costly.

Why humans find it interesting

Cultural Tradition

Francis Bacon described the tendency in 1620: the human mind, once it has adopted an opinion, draws everything else to support it.

CUE perspective

CUE Perspective

Any system of meaning, CUE included, is vulnerable to confirmation bias: a reading that fits feels like proof, and one that misses is forgotten.

CUE’s answer is to label interpretation as interpretation, and to invite you to notice the misses as well as the hits.

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Sources

  • Wason, “On the failure to eliminate hypotheses in a conceptual task”, Quarterly Journal of Experimental Psychology 12 (1960)
  • Lord, Ross & Lepper, “Biased assimilation and attitude polarization”, Journal of Personality and Social Psychology 37 (1979)
  • Nickerson, “Confirmation bias: a ubiquitous phenomenon in many guises”, Review of General Psychology 2 (1998)
  • Bacon, Novum Organum (1620), Aphorism 46

Written by CUE from the sources above. Some topics were suggested by Polymath; its claims are not reproduced.