Came across this link in an internet conversation. I kind of wish that I had come across this logic puzzle before I’d come across the Wikipedia entry on it, because I would have been interested to know whether or not I would have successfully deduced the correct answer on my own. (Apparently, a large percentage of people fail this test.)
An example of the Wason Selection Task is:
You are shown a set of four cards placed on a table, each of which has a number on one side and a colored patch on the other side. The visible faces of the cards show 3, 8, red and brown. Which card(s) must you turn over in order to test the truth of the proposition that if a card shows an even number on one face, then its opposite face is red?
A response that identifies a card that need not be inverted, or that fails to identify a card that needs to be inverted, is incorrect. The original task dealt with numbers (even, odd) and letters (vowels, consonants).