Card Problem (Wason Selection Task)
The Card Problem demonstrates confirmation bias: people tend to test a rule by seeking confirming evidence rather than attempting to falsify it.
THE IDEA
Card Problem
Make sure this rule is not violated: Vowel? Better be an even number on the other side.
- N—doesn’t matter whether there’s an even number on the back or not.
- 4—doesn’t matter whether there’s a vowel on the other side or not.
- A—better be an even number on the other side. If not, the rule is broken.
- 3—better not be a vowel on the other side. If so, the rule is broken.
When to use it
Scientific hypothesis testing: Designing experiments to falsify a hypothesis rather than confirm it.
Business decisions: Evaluating a new marketing strategy by actively seeking evidence that it might fail.
Legal reasoning: A juror considering evidence that both supports and contradicts the defendant's guilt.
Everyday problem-solving: Checking assumptions in a personal relationship by testing them instead of assuming they are correct.
FROM THEORY TO EVERYDAY LIFE
In practice
Classic Card Problem
Given four cards showing N, 4, A, and 3, with the rule: 'If a card has a vowel on one side, then it has an even number on the other.' Most people choose to flip A (to see if the other side is even) and 4 (to see if the other side is a vowel), but the correct choice to falsify the rule is to flip A and 3. Flipping 4 is uninformative because the rule does not require that an even number have a vowel on the other side.
A MOMENT TO REFLECT
Put it to work.
Why do most participants choose to flip the A and 4 cards instead of A and 3?
How does this task illustrate the human tendency toward confirmation bias?
Can you recall a time when you looked for evidence to support a belief rather than trying to disprove it?
CONTINUE THE CONVERSATION
Source texts
- Mindware Tools for Smart Thinking (Richard E. Nisbett)