I recently reread Rory Sutherland's book "Alchemy" and one rather striking 'lesson in Alchemy' was his highlight of the "Wason selection task" which I have recreated below for you as a fun exercise.
The Task
To begin, we introduce the cards below, two with visible grey faces that show the numbers 5 and 8, the other two are concealing their numbers and have blue and green on the back.
Which card (or cards) must you turn over in order to test the following proposition:
If a card shows an even number on one face, then its opposite face is blue.
Have a think for a bit and try and justify your answer. If you've been a rather active reader then you're more than welcome to contact me with your solution prior to revealing the answer to yourself.
What's the solution?
Well, rather than give you the solution outright, what I think is a more interesting approach is to instead shift the variables around a bit. We now have the following situation
- Replace 5 with 16.
- Replace 8 with 25.
- Replace blue with Coca Cola.
- Replace green with Guinness.
Now, on the grey side we have someones age and on the other side we replace colour for the drink in their hand, what card(s) do we have to turn over to test the proposition 'you have to be over 18 to drink alcohol'?
How fun is that! 'Til next time.
P.S. ⬇️
If you're super stuck, you can look up the solution by searching the name of the test.