In a variation on the “Wason selection task”, students in a research study were asked to test the rule “if a card has D on one side, it has a 3 on the other”. They were then shown four cards, which had either a letter (D or F) or a number (3 or 7) on them, and were asked which cards they would turn over to validate the rule. The correct answer was the D and 7 cards. If a D card had anything other than a 3 on the other side, the rule was disconfirmed; ditto if a 7 had a D on the other side.
Most students got it wrong – they said they would look at the F and 3 cards*. Their error was in seeking to confirm the rule, rather than disconfirm it. But a rule is only a rule if it applies across the board; therefore, all you have to do is find one instance where it doesn’t apply and the rule is invalidated.
Confirmation bias may be a default setting in the human psyche, but that doesn’t mean we can’t overcome it in specific cases. For instance, research subjects perform much better on simple logic tasks like the above when they are explicitly instructed to falsify a rule. Moral of the story: bias can be neutralized with education. There’s hope for humanity yet.
* Neither the F nor 3 card had any bearing on the question because nothing on the other side could disconfirm the rule.