logic & reasoning
the wason selection task
four cards, one rule, and the test that nine in ten educated adults fail.
In 1966 Peter Wason laid four cards on a table and asked a question of pure logic. It looks trivial. It is not: only around one person in ten selects exactly the right cards, and being clever is almost no help. Each card has a letter on one face and a number on the other.
If a card has a vowel on one side, then it has an even number on the other side.
Each card has a value on one side and another on its reverse. Select only the cards you must turn over to find out whether the rule is being broken: no more, no less.