Peter Cathcart Wason proposed a form of the following task, which is failed by 90 percent of people who attempt it (though users of this website have a better track record). Try the task yourself, and see how others responded. Then read the answer and explanation, and try a real-life version.
There are four cards, each of which has a number on one side and a color on the other. The cards lie on a table with the following faces showing: 3, 8, green, blue. The task is to identify which cards need to be turned over in order to test the truth of the following proposition: “If one of these cards has an even number on one side then its other side is green.” Which cards would you turn over, without turning over any cards unnecessarily?
Click Here to See Answer and Explanation The correct answer is that you must turn over only the 8 card and the blue card. Here is an explanation for each of the cards: A Real-Life Scenario The Wason task is difficult in part because it tests abstract logical reasoning. Many people perform better on a similar test based on a real-life scenario. Say that you work in a bar, stopping underage people from drinking. Your job is to test this rule: “If someone is drinking alcohol, then that person must be age 18 or older.” From where you are standing, you can observe four people: a person drinking soda (you can’t see how old they are); a person drinking beer (you can’t see how old they are); a 30-year-old person (you can’t see what they’re drinking) and a 16-year-old person (you can’t see what they’re drinking). Which of these four items must be checked in order to make sure the rule is being followed? For this task, your “cards” would look like this:
Logically, this task is identical to the first one. However, most people find it easier to figure out which cards need to be checked: the beer and the teenager.
hate you
Another victim! Bwahahaha. 🙂
If you turn over the blue it doesn’t prove [anything]. There’s no accurate way to tell if even must be green. Or else the question is poorly put
You are right that turning over the blue card cannot prove the statement, but it might disprove it. The task is to prove whether this statement is true or false: “If one of these cards has an even number on one side then its other side is green.” You know each card has a color on one side and a number on the other. With the blue card, imagine if the number 4 was on the other side. That would disprove the statement! So you have to check.
You may need to turn over the 8 card and the green card – without touching the blue card. The statement says that only ONE of the cards has to have a green side if it’s other side is an even number. Turn over the 8 card – if the other side is green, statement is true, ONE card has an even number with a green reverse. If the 8 card does not have a green reverse then one must turn over the green card. If it contains an even number, then the statement is true and no other cards are relevant. If it does not contain an even number then the statement is false and no other cards are relevant, since the 3 card is odd (thus the reverse is irrelevant) and the blue card is, well, blue – which is neither green nor an even number so it’s reverse is not relevant.
((x == 1) <= (y == 2)) == ((y != 2) <= (x != 1));
please explain
I liked it. I guessed the wrong answer immediately, before rereading the question and realising that the Green card didn’t need to be turned over. It was fun.
I like your attitude! 🙂
GATE 2017 GENERAL APTITUDE questions set by IIT ROORKEE is taken from here i think.. just see question 58 civil engg. set2..and ece set2 question 58. here is the link to question papers http://www.gate.iitr.ernet.in/?page_id=485
Humans can’t think logically? You don’t say!
It’s still interesting, to find out in which ways exactly Humans are illogical. Then we can take countermeasures 🙂
I think the main reason this trips so many people up is because it’s based on logical syllogism language rather than spoken language. It’s almost like a trick question due to unfamiliar wording not used in normal conversation…or by non-robots lol. The “if p then q” crowd (undergrad philosophy majors) had a major leg up on this one 😂
But what about the 3 card? Surely that has to be turned over following on from the same logic as that for turning over the blue card. We are left to ASSUME that every number is backed by a colour – not necessarily. What if we turn over the 3 card and there’s an even number on its reverse – the statement would be false.
Actually no – ignore that! It’s neither green nor even, and only one of the cards has to fit the criteria. So, why check the blue? If the 8 isn’t green, then we check the green. If it is not an even number on the reverse then the statement is false.
There are only two ways the statement can be true:
1. The 8 card has a green reverse
2. The green card has an even number on its reverse.
Check the 8 card. If the reverse then the statement is true. If it’s not green, check the green card. If the reverse of the green card contains an even number then the statement is true. If it does not then the statement is false.
We know all we need to know already about the 3 and blue cards. Neither can make the statement true, so we can ignore them.
But if you turn over the blue card and it has an even number, then it disproves the statement, even if the 8 and green cards support the statement.
It doesn’t disprove the statement. It says if ONE card has an even number then its reverse will be green. If either the green or the 8 has a reverse that makes the statement true, then it does not matter about the blue. The rule says nothing about the blue card.
It is stated in the question that every card has a number on one side and a color on the other.