Psycho Wednesday #1 Confirmation bias

It’s a first post from new The Psycho Wednesday Collection. In the Psycho Wednesday I am shortly describing the most important ideas or theories of psychology and sociology. I strongly belive the collection will be useful for adept-researchers and for experienced researchers who want to refresh their knowledge.


 Confirmation Bias


“In psychology and cognitive science, confirmation bias (or confirmatory bias) is a tendency to search for or interpret information in a way that confirms one’s preconceptions, leading to statistical errors.

Confirmation bias is a type of cognitive bias and represents an error of inductive inference toward confirmation of the hypothesis under study.

Confirmation bias is a phenomenon wherein decision makers have been shown to actively seek out and assign more weight to evidence that confirms their hypothesis, and ignore or underweigh evidence that could disconfirm their hypothesis.”



We can describe 3 types of confirmation bias. I will describe them with examples from ux researcher’s job:


Biased search for information

“Experiments have found repeatedly that people tend to test hypotheses in a one-sided way, by searching for evidence consistent with their current hypothesis. Rather than searching through all the relevant evidence, they phrase questions to receive an affirmative answer that supports their theory.” (source: wikipedia)

I was working with softwarehouse which created some website for a bank. When I saw this website for the first time I was sure: it was bad. Just bad.  The website wasn’t useful or user friendly… During tests with users, which I conducted, I was just looking for information which fitted my private opinion.  So, I mostly asked people about the worst elements of the website, which they couldn’t describe positively.

Good advice: Before you start a research project, it’s good to spend a minute to consider your feelings about the website or application you’re going to test. This will help you later to confront your opinion with opinions of resondents.


Biased interpretation

People can also understand the same information in biased way:

Designers who made the website observed all interviews. After every single interview I was going to talk with them about experience of participants. I was shocked! They were listening the same people, but they understood participants’ words in oposite way than me. E. g., when I was sure that the participant didn’t like the website – they were sure that he really enjoyed it.

Good advice: You can engage two researchers in one project – this helps in objectifying the research conclusions.


Biased memory

Sometimes people remember some facts in a selective way, even if they gathered and interpreted them in a neutral manner.

After test with a first participant you have some insights. After every next interview you will judge first impressions through the prism of newest insights.

Good advice: I recommend you to take notes after every single interview, when your memories are fresh.


All researchers are exposed to confirmation bias (even experienced researchers!). It’s good to remember about it and be watchful.

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