Are you among the 10 percent that can solve this tricky puzzle? I lay out the four cards you see below. Each card has a color on one side and a number on the other. The rule is that if a card has an even number on one side, then the other side must be red. However, one of the four cards breaks that rule.
How do you determine which one breaks the rule? You're allowed to flip over as many cards as you want. But if you flip a card that doesn't help you find the rule-breaking card, then you lose. Which card or cards would you turn over?
The interesting part is that this puzzle reveals how people think. Most people will try to confirm what they think they know instead of using logic to figure out the unknown. A psychologist named Peter Wason invented this puzzle in the 1960s. His students said that he wanted to "explore the nature of thinking."
If you change one little variable, the success rate jumps from 10 percent to 75 percent. Most people can solve this version:
These four cards represent four people. Their age is on one side of the card and the beverage they are drinking is on the other. Which cards do you need to flip to determine if someone is drinking underage?
Click here to get a video explanation of both puzzles.