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Exploring the Wason Card Selection Task

The solution to the Wason Card Selection task is provided here.
Four cards showing Burned Paper Did not burn and Plastic - the rule being If it's paper, it will ignite at481F
© The University of York

The solution

Let’s take each of the cards in turn…

You should turn the A card over.

Why? Well it has to have an even number on the other side for the rule to be true – this is a direct test of the rule. If an odd number is discovered, then the rule has to be false.

What about the K card? Well this card is simply irrelevant. The rule is about the relation between vowels and even numbers and K is a consonant so forget about it.

Now because the rule mentions vowels and even numbers, we might be tempted to reach for the 4 card. But again, do not be seduced into touching this card. Let’s say you turn it over and there is ‘U’ on it. Well yes that is consistent with the rule but not helpful. Indeed if you turn it over and it has a consonant on the back that result has no bearing on the rule. It’s all about how vowels are related to even numbers not about how even numbers are related to vowels.

So Yes to A and No to K and 4 so what about 7?

Well if you turn the 7 over and it has a consonant on the back then that’s not helpful, BUT if you turn it over and it has a vowel on the back then that is the killer result. What that outcome would show is that the rule is false and you can categorically say that it is false – job done. So the correct answer is to turn the A card over and the 7 card.

Mulling over all this, it is probably best to remember only about 4% of students get this right. You might think why this is? Remember the confirmation bias???

© The University of York
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