IMAGINE there are four cards on a table in front of you, on which are written
“A”, “D”, “4” and “7”. You are told that each card has a number on one face and
a letter on the other. You are also told that the rule is that a card with a
vowel on one side has an even number on the other. Which card/cards do you have
to turn over to find out whether the rule holds true? This is a version of the
Wason test beloved of experimental psychologists. It would be a disservice to
the discipline to…
Science Needs You
3 June 2000
