What is confirmation bias?
Quick answer
Confirmation bias is the tendency to search for, notice, interpret and remember information in a way that supports what we already believe, while overlooking evidence against it. It affects everyone, from scientists to sports fans. English psychologist Peter Wason helped popularize the idea with experiments in the 1960s.
The 2-4-6 experiment
In 1960, Wason told participants that the numbers 2, 4, 6 followed a secret rule and asked them to discover it by suggesting other sets.
| What most people did | What happened |
|---|---|
| Guessed “even numbers going up by 2” | Tested sets like 8-10-12 or 20-22-24, which fit their idea |
| Rarely tested sets that might disprove it | The real rule was simply “any increasing numbers” |
People looked for confirming examples instead of trying to prove themselves wrong.
Everyday examples
| Area | Example |
|---|---|
| News and social media | Following sources that agree with us, and algorithms that show us more of the same |
| Sports | Remembering the referee’s bad calls against your team, but not those in your favor |
| Health | Remembering the one time a remedy “worked” |
| Investing | Seeking only good news about a stock you own |
| First impressions | Noticing behavior that confirms your view of someone |
Different forms
- Biased search: looking only for evidence that fits
- Biased interpretation: seeing unclear evidence as support
- Biased memory: remembering hits and forgetting misses
How to counter it
- Ask: “What would change my mind?”
- Look deliberately for the strongest opposing argument.
- Read sources with different viewpoints.
- In decisions, have someone play devil’s advocate.
- In science, design tests that could disprove a hypothesis.
The scientific method is built partly to guard against confirmation bias, through peer review, control groups and repeating experiments.
Related biases
| Bias | Meaning |
|---|---|
| Belief perseverance | Keeping beliefs even after evidence is discredited |
| Spotlight effect | Overestimating how much others notice us; see what the spotlight effect is |
| Mandela effect | Shared false memories; see what the Mandela effect is |
For how scams exploit our assumptions, see what phishing is.
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