How we change what others think, feel, believe and do
When we have made a decision or build a hypothesis, we will actively seek things which will confirm our decision or hypothesis. We will also avoid things which will disconfirm this. The alternative is to face the dissonance of being wrong.
We use this approach both for searching our memory and looking for things in the external world. This has also been called the Positive Test Strategy.
Confirmation bias has also been called Confirmatory Bias, Myside Bias and Verification Bias.
Snyder and Cantor (1979) gave participants a description of a person called Jane that included mixed items such as sometimes showing her as introverted and sometimes as extraverted. A couple of days later, half were asked to assess her for an extraverted job (real estate agent) and the rest asked to assess her for a librarian's job. Each group were better at remembering the attributes that supported the job for which they were assessing. This implied they were using a positive-test strategy when trying to remember things about Jane.
After having bought a piece of clothing, we will look for the same clothing in a more expensive store to confirm that we have bought a bargain.
This is caused by the post-decisional dissonance between the decision made and the possibility of being wrong.
After having persuaded a person of something, help them feel good by letting them find examples that confirm their good example.
After a decision is made, consider whatever evidence you can find, even if it disconfirms the decision—at least you will make a better decision next time. Also beware of people feeding you confirming evidence.