Confirmation Bias
Also known as: myside bias, congeniality bias
The tendency to seek out, favor, and remember information that supports what you already believe — and to overlook or discount whatever cuts against it.
Examples
Marta believes her town’s new traffic layout has made congestion worse.
Marta: “See? Stuck again. This new layout is a disaster.” Jonas: “We were stuck here most mornings before the change too.”
Marta notices every jam and forgets every smooth ride, so her experience keeps “proving” what she already thought.
Online, it shapes what we search for:
Post: “Does coffee stunt growth? Asking for my teenage son.” Reply: “I googled ‘evidence coffee stunts growth’ and found loads of hits, so yes.”
Searching only for the confirming phrase guarantees confirming results. Searching “does coffee affect growth” would have surfaced the opposite answer too.
Why it happens
Testing a hunch by looking for matches is fast and usually feels like honest research. Psychologists have documented the pattern for decades: people prefer information sources that agree with them, read agreeable evidence less critically, and recall it more easily later. Checking for disconfirming evidence, by contrast, takes deliberate effort and feels vaguely disloyal to your own position.
The result is a loop: the more you believe something, the more supporting material you accumulate, and the stronger the belief feels — regardless of how the total evidence actually stacks up. Doing this deliberately in an argument is the cherry picking fallacy; confirmation bias is the quieter, unintentional version that happens while you think you’re being fair.
How to counter it
- Ask what would change your mind, before you look. If nothing could, you’re not evaluating evidence — you’re defending a verdict.
- Search against yourself: look up “evidence against X” in the same session you look up “evidence for X”.
- Track misses, not just hits. Marta’s fix is boring but effective: note the commute time every day for two weeks, not just on bad days.
- Give the other side one honest read. Read the strongest opposing source the way you read a friendly one — slowly, and looking for what it gets right.
Expect this to feel unnecessary. It feels that way to everyone — see the bias blind spot.