Confirmation bias
Your brain isn't looking for the truth. It's looking to be right.
One of the best-documented biases, observed both in the lab and in real-world settings such as medicine, law and science.
Sound familiar?
You decide someone rubs you the wrong way "for a reason". From then on you notice every rude gesture they make and forget the kind ones. A few weeks later you have plenty of "evidence". But did you look for it fairly?
What it is
Confirmation bias is the tendency to search for, interpret and recall information in a way that confirms what we already think. We don't do it on purpose: it happens automatically, and it affects everyone, including highly intelligent and well-educated people.2
It works at three stages: what we look for (questions that can only prove us right), how we interpret it (we read ambiguous information in our favour) and what we remember (hits stick, misses fade).
The experiment
In 1960, British psychologist Peter Wason came up with a simple game.1 He showed participants the sequence 2-4-6 and told them it followed a secret rule. Their task was to work it out by proposing other three-number sequences; he would only answer "fits" or "doesn't fit".
Most people quickly settled on "even numbers going up by two" and tried things like 8-10-12 or 20-22-24. Every one fitted, so they became convinced they were right. But the real rule was much simpler: any ascending sequence.
The problem? Hardly anyone tested a sequence that could disprove their idea, such as 1-2-3 or 6-4-2. They only looked for confirmation.
What we know today
A classic review by Raymond Nickerson (1998) brought together decades of research and concluded that the bias shows up "in many guises" and in many areas: doctors who cling to their first diagnosis, researchers who read data in favour of their hypothesis, and juries who weigh evidence according to their first impression.2
One important nuance: seeking confirmation can be a reasonable strategy when time or information is short. The problem arises when we never check the opposite, especially for important decisions.
Myth vs. reality
Myth "It only happens to people who don't think things through."
Reality It's a general tendency of the human mind. Knowing about it helps, but it doesn't make you immune. You need concrete habits to counter it.
In everyday life
- Ask the opposite question: what would I need to see to change my mind?
- Deliberately look for the strongest version of the opposing argument, not the weakest.
- Check your feed: algorithms show you more of what you already like, which feeds the bias.
Sources
- Wason, P. C. (1960). On the failure to eliminate hypotheses in a conceptual task. Quarterly Journal of Experimental Psychology, 12(3), 129–140. doi.org/10.1080/17470216008416717
- Nickerson, R. S. (1998). Confirmation bias: A ubiquitous phenomenon in many guises. Review of General Psychology, 2(2), 175–220. doi.org/10.1037/1089-2680.2.2.175