Four cards are placed in front of you on the table, each with a number on one side and a color on the other. The visible cards show 3, 8, red and brown. Which cards should you turn over in order to test the truth of the statement that if a card shows an even number on one face, then its opposite face is red?
You’d need to turn over only the 8 and brown card. Only a card with an even number on one face and which is not red on the other face can invalidate the stated rule. If you turn over the 3 card and it’s not red, it doesn’t invalidate the rule, nor does turning over the red card and finding it has the label 3.
This test was devised by Peter Cathcart Wason and is known as the Wason selection task. Less than 10% of test subjects got it correct in two separate studies.
I am, in truth, a yellow fork From tables in the sky By inadvertent fingers dropped The awful cutlery. Of mansions never quite disclosed And never quite concealed The apparatus of the dark To ignorance revealed.
Lucrezia Borgia invited a prospective victim to lunch. They ate a hearty meal of roast venison, with a selection of fresh vegetables, all washed down with the finest wine imported from Bordeaux, France.
After the meal, they ate figs and freshly picked grapes.
“Just one apple left”, said Lucrezia, “I insist you have it.
“No”, said the guest, “I couldn’t”.
“Tell you what”, said Lucrezia, “we’ll share it”, and promptly sliced the apple in two with her sharpest knife. The guest and Lucrezia started to eat their respective halves when the guest’s eyes rolled towards the ceiling and he fell over, dead.
“Another victim successfully dispatched,” thought Lucrezia.
A man gets off the bus looking for an address and approaches a couple walking in the same direction for directions. The woman says they’re going that way and take him. Along the way the man asks if they’re related. The woman grins and says, “We’re not strangers. This man’s mother is my mother’s mother-in-law.” The man is confused but doesn’t say anything. When he gets back home he tells his wife about the conversation and she can’t figure it out either. They decide to ask their lawyer and he eventually works it out with pen and paper. How are the couple related?
