Confirmation Bias: A Ubiquitous Phenomenon in Many Guises
Raymond Nickerson · 1998
"People systematically seek out, interpret, and remember information in ways that confirm their existing beliefs, while ignoring or discounting evidence that contradicts them — making it one of the most pervasive and hardest-to-correct biases because it operates on what evidence gets noticed in the first place, not just how it's judged afterward."
Nickerson's review pulls together decades of scattered research to show confirmation bias isn't one narrow effect but a pattern that shows up in nearly every stage of reasoning: which questions we choose to ask, which sources we choose to consult, how we interpret ambiguous evidence, and what we remember afterward. All of these steps tend to tilt toward confirming what we already believed going in, often without any conscious intent to be biased.
The bias operates at three points: search, where we ask questions designed to confirm rather than test our hypothesis, a behavior demonstrated experimentally by Peter Wason's earlier rule-discovery studies which Nickerson's review builds on; interpretation, where ambiguous or mixed evidence gets read as supporting our existing view; and memory, where confirming instances are recalled more easily than disconfirming ones. Because it acts this early and this broadly, simply presenting someone with contradicting facts often fails to correct it — the facts get filtered, reinterpreted, or forgotten before they can do their work.
According to Nickerson, why is confirmation bias particularly hard to correct?
Read more about the topic
The explanation above is written with AI assistance. These are the originals — go to them to check it.
- Confirmation Bias: A Ubiquitous Phenomenon in Many Guises (full paper)UC San Diego
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