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.
A sharpshooter hangs up his hat, turns around and walks 5000 meters in one direction, then turns around and shoots his gun, putting a hole right through his hat. How did he do it?
1. How do you put a giraffe into a refrigerator? 2. How do you put an elephant into a refrigerator? 3. The Lion King is hosting an animal conference. All the animals attend except one. Which animal doesn’t attend? 4. There is a river you must cross but it is used by crocodiles and you don’t have a boat. How can you cross safely?
1. Open the refrigerator, put the giraffe in and close the door. It’s not complicated. 2. Open the refrigerator, take out the giraffe, then put in the elephant and close the door. 3. The elephant. He’s still in the refrigerator. After all, you just put him there. 4. Jump into the river and swim across. The crocodiles are at the Lion King’s animal meeting. I admit, this is not a typical brain teaser, but it amused me.
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?
I was visiting a friend one evening and remembered that he had three daughters. I asked him how old they were. “The product of their ages is 72,” he answered. Quizzically, I asked, “Is there anything else you can tell me?” “Yes,” he replied, “the sum of their ages is equal to the number of my house.” I stepped outside to see what the house number was. Upon returning inside, I said to my host, “I’m sorry, but I still can’t figure out their ages.” He responded apologetically, “I’m sorry, I forgot to mention that my oldest daughter likes strawberry shortcake.” With this information, I was able to determine all three of their ages. How old is each daughter?
The house number alone would have identified any of these groups. Since more information was required, we know the sum left the answer unknown. The presence of a single oldest child eliminates “2 6 6”, leaving “3 3 8” as the only possible answer.
