Confirmation Bias
Category: cognitive Origin: Peter Wason, 1960 Tags: belief, perception, search, reasoning, information
Summary
The tendency to search for, interpret, and recall information in a way that confirms one’s pre-existing beliefs while ignoring contradicting evidence.
Mechanism
- Person holds a belief or hypothesis
- When seeking information, they preferentially notice and remember confirming data
- Contradicting data is dismissed, reinterpreted, or not sought at all
- Belief strengthens regardless of actual evidence quality
- Loop reinforces over time — belief becomes harder to challenge
Triggers
- Strong emotional investment in a belief
- Group identity tied to a belief
- High uncertainty — mind anchors on first available explanation
- Prior decisions that are hard to reverse
- Social environments with homogeneous views
Effects
- Overconfidence in beliefs
- Poor decision-making due to incomplete evidence
- Echo chambers and polarization
- Resistance to correction even with hard evidence
- Distorted memory of past events to fit current beliefs
Examples
Example 1 — Politics: A person who supports a political party reads news that confirms their party’s positions and dismisses or avoids outlets that challenge them.
Example 2 — Hiring: A manager forms a quick positive impression of a candidate and asks questions designed to confirm that impression rather than probe weaknesses.
Example 3 — Medical self-diagnosis: Someone convinced they have a specific illness googles symptoms that match and ignores symptoms that don’t.
Counters
- Actively seek disconfirming evidence — ask “what would prove me wrong?”
- Use pre-mortems: imagine your belief is wrong and explain why
- Expose yourself to structured opposing viewpoints
- Separate belief evaluation from identity
- Use checklists and base rates instead of intuition alone
Related Models
- Cognitive Dissonance — confirmation bias is often a coping mechanism for dissonance
- Availability Heuristic — biased recall feeds confirmation
- Dunning-Kruger Effect — overconfidence amplifies confirmation bias
References
- 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.