Send station · the claim, dispatched
Confirmation Bias
The seeking or interpreting of evidence in ways that are partial to existing beliefs, expectations, or a hypothesis in hand.
Supports
The bias files watch for information searches that only examine cases consistent with your preferred hypothesis as confirmation.
Biased Assimilation and Attitude Polarization
Both groups rated the study supporting their prior view as more convincing and better conducted
n≈48
Refutes / corrects
2-4-6 Rule Discovery Task
Only 6 of 20 subjects reached the correct conclusion without previous incorrect conclusions
n≈20
Positive Test Strategy
Many phenomena labeled confirmation bias reflect a general tendency to test cases expected to have the target property
qual.
In the wild
Brandon Mayfield Madrid Bombing Fingerprint Misidentification
Following the 2004 Madrid train bombings
2004
Jeffrey Deskovic Wrongful Conviction
After 15-year-old Angela Correa was murdered in Peekskill
1990
Bladimil Arroyo False Confession Case
In 2001
2001
Dispatch log · replication mixed. The basic confirmatory testing tendency in Wason's 2-4-6 task has been widely replicated. Selective exposure effects are robust (Hart et al., 2009 meta-analysis, N > 4,000). However, Lord et al.'s (1979) attitude polarization finding has failed to replicate when using direct pre-post measures rather than self-reported change (Miller et al., 1993; Kuhn & Lao, 1996). Modern replications suggest updating does occur in the direction of evidence, but prior beliefs modulate the magnitude.
Pressure diagram · why it sorts this way
Confirmation bias operates through multiple mechanisms: (1) selective exposure - seeking information consistent with prior beliefs; (2) biased assimilation - interpreting ambiguous evidence as supporting existing views; and (3) selective memory - recalling confirmatory instances more readily. Klayman and Ha (1987) argued that the positive test strategy is cognitively efficient because positive information is more accessible than negative information. Motivated reasoning accounts (Kunda, 1990) add that directional goals can amplify confirmatory search.
The positive test strategy view (Klayman & Ha) treats confirmation bias as a cognitively efficient default rather than a motivated desire to confirm. The argumentative theory (Mercier & Sperber) frames myside bias as adaptive for social persuasion.
Manual override
Actively seek disconfirming evidence by considering alternatives and asking what would prove your hypothesis wrong. Baron et al. (1988) found that explicitly considering alternative hypotheses or probabilities of negative results reduces congruence bias.
Studies show that generating explicit alternatives (Tweney et al., 1980) or asking either-or questions rather than yes-no questions (Hodgins & Zuckerman, 1993) significantly improves hypothesis testing accuracy.
Adjacent stations
- Congruence BiasCongruence bias is a narrower form of confirmation bias focused specifically on evaluating diagnostic questions by their probability of yielding a positive answer under the favored hypothesis.
- Myside BiasMercier and Sperber distinguish myside bias (seeking evidence for one's own position) from the broader tendency to confirm any focal hypothesis.
- Belief PerseveranceBelief perseverance and confirmation bias form a reinforcing loop: once a belief is held, confirmatory search maintains it even against disconfirming evidence.