Most people test conditional rules by matching the terms named rather than by seeking falsifying cases.
Wason's 1966 task. Given cards and a rule about vowels and even numbers, most people turn the cards named in the rule rather than the card that could falsify it. Concrete social framings raise performance sharply.
In practice
- An auditor testing "every invoice over £10,000 carries two signatures" pulls the large invoices, and not the singly signed ones that would show a breach.
- The same auditor asked to check that nobody under eighteen was served alcohol looks straight at the young drinkers and the people holding beer, and gets it right.
- Further reading
- Wikipedia
- Subject
- Psychology & Behavior
- Essay
- A century and a half of measuring the mind