Debriefing
Click here to see the cards you turned over for the first task, where the rule was if there is a square on one side, there must be a vowel on the other side.
Click here to see the cards you turned over for the second task, where the rule was if the movie is R-rated, the person must be 18 years old.
Click here to see the correct answer.
Click here to see the correct answer.
Click here to see the typical answer.
Most people choose 2 and 4, even though the correct answer is 3 and 4. Most people know to turn over the card with the square on it to confirm the rule that if there is a square on one side of the card, there must be a vowel on the other side.
Click here to see how you did on the movie theatre task
1
2
3
4
But there are also two mistakes commonly made, and those are of interest to cognitive psychologists. First, people tend to choose to turn over card 2, with the vowel on it. This is explained as being a result of confirmation bias; people tend to look for information that confirms a rule even when their job is to find out if a rule isn't being followed. If the vowel is turned over and a circle is on the other side, has the rule if there is a square on one side of the card, there must be a vowel on the other side been broken? No. Because, "if A, then B" does not mean, "if B, then A". So whatever is on the other side of the vowel doesn't matter! Clearly people don't use syllogistic reasoning as well as we may think! The second mistake most people make is NOT checking the other side of card3 with the C on it. This is a crucail step if you want to know whether all cards with squares have vowels on the other side -- if there is a square on the other side of the C card, the rule has been broken! The fact that people rarely choose to turn over the C card shows again that people look for confirming evidence and are poor at syllogistic reasoning.