First of all, the authors present a typical Wason Selection Task like the following:
Using First-Order logic this problem is easily solvable. However, 70% to 95% of participants get this wrong. The task dissolves to a simple "If P Then Q" statement, all of the cards correspond to states of this first-order logical statement. The 3 card corresponds to Not-P, 8 card corresponds to P, Red card corresponds to Q, and the brown card corresponds to Not-Q. If you haven't figured it out, the correct answer is to turn over the card corresponding to P and the card corresponding to Not-Q. In this case the answer is [8] and [Brown].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) should 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? Wason selection task, http://en.wikipedia.org/w/index.php?tit ... =338009127 (last visited Jan. 21, 2010)
Cosmides and Tooby suspected that using Social Contract Theory the correct answers could be obtained from most participants by rephrasing the selection task in the form of cheater detection. Consider the following example:
In this latter case most people select P & Not-Q, the correct answers, however they are not selected for logical reasons. An illogical inference is made based on a reverse of the original statement "If you fill the tank up with gas, you can borrow my car." Reversing the original statement in First-Order Logic would be invalid, try this out with the first example.Teenagers who don't have their own cars usually end up borrowing their parent's cars. In return for the privilege of borrowing the car, the Carters have given their kids the rule,
"If you borrow my car, then you have to fill up the tank with gas."
Of course, teenagers are sometimes irresponsible. You are interested in seeing whether any of the Carter teenagers broke this rule.
The cards below represent four of the Carter teenagers. Each card represents one teenager. One side of the card tells whether or not a teenager has borrowed the parents' car on a particular day, and the other side tells whether or not that teenager filled up the tank with gas on that day.
Which of the following card(s) would you definitely need to turn over to see if any of these teenagers are breaking their parents' rule: "If you borrow my car, then you fill up the tank with gas." Don't turn over any more cards than are absolutely necessary.
[Borrowed Car] [Did not borrow car] [filled up tank with gas] [ did not fill up tank with gas]
- Moral Psychology by Walter Sinnot-Armstrong, p. 79, fig 2.2
"if a card shows an even number on one face, then its opposite face is red"
"if a card shows red on one face, then its opposite face is an even number"
The two statements aren't equivalent, and I had no idea that with typical social contracts one could get away with reversing the statements. To reverse the social contract about borrowing the car is to create a different rule, in that case there is a sense of entitlement that arises from filling the tank with gas. "Last time I borrowed the car I filled it with gas, so I am entitled to borrow it again.". Apparently this is normal thinking, its illogical in this case, but the answers given are the correct answers, whereas in the first case the correct answers are not given by the vast majority of participants.
Interesting insight into the operations of the human mind.