The Wason selection task (or four-card problem) is a logic puzzle devised by Peter Cathcart Wason in 1966. It is one of the most famous tasks in the study of deductive reasoning. In Wason's study, not even 10% of subjects found the correct solution. This result was replicated in 1993. I'm betting Scratchers will do better! Which card(s) must be turned over to test the idea that if a card shows an even number on the face, then its opposite face is red?
Press space to see % who answered correctly. http://en.wikipedia.org/wiki/Wason_selection_task
