One of the most famous experiments in deductive reasoning is The Wason Selection Task. Peter Wason developed the logic puzzle in 1966 to determine how good people are at solving tasks that require deductive reasoning. 8
The experiment was set up as follows:
“You are shown a set of four cards placed on a table, each of which has a number on one side and a colored patch on the other side. The visible faces of the cards show 3, 8, red and brown. Which card(s) must you turn over in order to test the truth of the proposition that if a card shows an even number on one face, then its opposite face is red?”
The correct solution is to turn over the brown card, and the card with the number 8. Did you figure it out?
The puzzle is solved by applying a “if P, then Q” argument structure, and deciding which cards you need to see to ensure the proposition is true. So in this case, If the brown card is even, it violates the rule, and if the card with 8 is not red, it violates the rule. It doesn’t really matter what colour is on the back of the 3 card, since the proposition makes no claims about odd numbers. Nor are we concerned by whether the red card is odd or even because although we are told that all even numbers are red, the proposition does not claim that all red cards are even, or odd for that matter.
What makes this experiment (and it’s 1993 replication) really interesting, is that although most people fail miserably at the task when it’s presented in this structure (<10% answer correctly), they perform much better when the same puzzle is applied in a more realistic context, or a scenario that’s easier to imagine.
For instance, Cosmides and Tooby (1993) showed that people were able to solve similar puzzles when they considered them under social rules or norms. Their task involved the rule “In order to drink alcohol, you must be over 25”, and instead of numbers and colours, they asked participants to imagine a group of people in a bar, with some drinking beer and others drinking coca-cola. They wrote the ages of individuals on one side of the card, and the beverage they were consuming on the other. So a card that showed 16, couldn’t show ‘drinking beer’ on its’ flip-side. In this setting, the vast majority of people reached the correct solution, even though the fundamentals of the task were the same. This finding lends support to the evolutionary school of psychology, and the argument that human reasoning is influenced by contextual factors and stimuli in our environment.