Confirmation Bias
We seek, favour and remember evidence that fits what we already believe.
Also known as: My-side bias
beginner Attributed to Peter Wason · Cognitive psychology
Confirmation bias is the tendency to search for, interpret and recall information in a way that confirms our existing beliefs, while giving disconfirming evidence far less weight. It makes us feel we're reasoning when we're really just defending.
What it is
Once we hold a view, we don't examine it neutrally — we look for support. We type searches likely to return agreement, read the sources that already align with us, interpret ambiguous evidence as confirming, and forget the cases that didn't fit. Each step feels like open-minded inquiry; together they form a closed loop.
The bias is powerful because it's largely invisible from the inside. Disconfirming evidence is subjected to harsh scrutiny ("that study was flawed"), while confirming evidence sails through unquestioned. The result is unwarranted confidence: we've "looked into it" and found only agreement, because agreement is all we let in.
It's amplified by the modern information environment, where you can always find someone who agrees, and where recommendation systems feed you more of what you already clicked.
Worked example
An investor buys a stock, convinced it will rise. Afterwards they read bullish analyses, follow optimistic commentators, and dismiss bad news as "noise" or "short-term." A warning sign that would have stopped them from buying now gets explained away, because selling would mean admitting they were wrong. The same fact means "don't buy" before the purchase and "stay calm" after it — the belief, not the evidence, decided.
How to counter it
This entry describes the trap; the way it misleads is the point. The specific danger is that confirmation bias feels like diligence — the more you research within a biased frame, the more confident and wrong you become. Counter it by actively seeking the strongest case against your view, not by researching harder in the same direction.
How to apply it
- Before deciding, deliberately seek the best argument against your view.
- Ask "what evidence would change my mind?" — if none would, that's a red flag.
- Steel-man the opposing case until you can state it fairly.
- Notice when you scrutinise disagreeing evidence harder than agreeing evidence.
Related entries
Sources & further reading
Thinking, Fast and Slow
by Daniel Kahneman · book
Kahneman describes how associative memory manufactures coherence from confirming evidence.
Affiliate link — we may earn a commission, at no extra cost to you.