The Wason Selection Task

There are four cards, a simple rule, and all you've got to do is to work out which cards you need to turn over to see if the rule has been broken. That's got to be easy, right? Well maybe, but the Wason Selection Task, as it is called, is one of the most oft repeated tests of logical reasoning in the world of experimental psychology. So let's see how you do.

There are three questions to complete, each one associated with a set of four cards. Here's the first question.

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Question 1

You are a quality control technician working for a card games manufacturer. You have to ensure that cards have been produced in accordance with the following rule:

If a card has a circle on one side, then it has the colour yellow on the other side.

You already know for certain that every card has a shape on one side and a colour on the other side. Please indicate, taking this into account, which card or cards you definitely need to turn over, and only that or those cards, in order to determine whether the rule is broken in the case of each of the four cards below. (To indicate that it is necessary to turn over a card, simply "select" the card by clicking in the little box beneath it.)