The Wason Selection Task


Here we will show you some examples of Wason selection tasks.  We will also show you how the mind sees each kind of rule.


For a Wason task with a descriptive rule, <click here>

For the logical structure of a Wason task, which applies to all rules, <click here>

 

For a Wason task with a social contract rule, <click here>

For how the mind "sees" a social contract rule, <click here>

 

For a Wason task with a precautionary rule, <click here>

For how the mind "sees" a precautionary rule, <click here>

 

To see why social contracts activate cheater detection, and NOT logical reasoning, <click here>

(that is, to see the relevance of experiments with standard versus switched social contracts)


Wason selection task with a descriptive rule.

In the following Wason task, the rule is descriptive.  That is, it describes an aspect of the world (it does not prescribe – that is, it does not tell someone what they should do.)  If you find this one difficult, it means... you have a normal human mind.  This problem elicited the logically correct response from only 20% of UCSB undergraduates.

To see the structure of this rule in logical terms, <Click here>


David planted a lovely garden with flowers of every color.  He has not been able to enjoy it, though, because deer from the forest nearby have been nibbling on his plants, killing some of them. 

He would like to keep the deer out of his garden.  His grandmother said that in the old days, she kept deer away by spraying an herbal tea -- lacana -- in her garden. She said:

"If you spray lacana tea on your flowers, deer will stay out of your yard."

This sounded dubious.  So David convinced some of his neighbors to spray their flowers with lacana tea, to see what would happen.  You are interested in seeing whether any of the results of this experiment violate Grandma's rule.


The cards below represent four yards near David's house.  Each card represents one yard.  One side of the card tells whether or not lacana tea was sprayed on the flowers in a yard, and the other side tells whether or not deer stayed out of that yard.


Which of the following cards would you definitely need to turn over to see if what happened in any of these yards violated Grandma's rule:


"If you spray lacana tea on your flowers, deer will stay out of your yard."


Don't turn over any more cards than are absolutely necessary.

 

 

sprayed with lacana tea

 

 

not sprayed with lacana tea

 

 

deer stayed away

 

 

deer did not stay away

 

 

The general structure of a Wason selection task.


Now that you have experienced a Wason task first hand, here is a description of its general structure, expressed in logical terms.

 

The following rule holds:  “ If  P then Q”. 


The cards below have information about four situations.  Each card represents one situation.  One side of a card tells whether P happened, and the other side of the card tells whether Q  happened. Indicate only those card(s) you definitely need to turn over to see if any of these situations violate the rule.


                                                                                                                                      

 

P

 

 

not-P

 

 

Q

 

 

not-Q

 

The logically correct answer is to choose the P card (to see if there is a not-Q on the back) and the not-Q card (to see if there is a P on the back).  This is because the rule is violated by any situation in which P happens and Q does not. 



Wason selection task with a Social Contract rule


Here is a social contract problem, in the standard format (where the correct cheater detection answer is the same as the logically correct answer.  To see a switched format, click here).  When translated into logical terms, this problem has the same structure as the descriptive one above (of course, the mind does not "see" it in logical terms).  In contrast to the descriptive rule, this social contract elicited the correct cheater detection response (which also happens to be the logically correct response) from 76% of UCSB undergraduates.

 

To see how the mind "sees" this problem, <click here>


Teenagers who don’t have their own cars usually end up borrowing their parents’ cars.  In return for the privilege of  borrowing the car, the Goldstein’s have givein their kids the rule,


“If you borrow my car, then you have to fill up the tank with gas.”


Of course, teenagers are sometimes careless and irresponsible.  You are interested in seeing whether any of the Goldstein teenagers broke this rule.


These cares represent four of the Goldstein 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 cards 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 have to 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

 



General Structure of a Social Contract Problem


The social contract above has a standard format -- i.e., the format where the correct answer if one is detecting cheater is the logically correct answer.  (For the switched format, the correct cheater detection answer is not a logically correct answer)  No matter how a social contract is phrased, to detect cheaters one must always investigate the person who accepted the benefit and the person who did not satisfy the requirement.


The cards in blue are the ones that should be chosen to detect cheaters.


The following rule holds:


“If you take the benefit, then you must satisfy the requirement.”

(If               P                  then                          Q                      )


You want to find out whether this rule is ever violated.  The cards below have information about four people.  Each card represents one person.  One side of a card tells whether a person accepted the benefit, and the other side of the card tells whether that person satisfied the requirement.  Indicate only those card(s) you definitely need to turn over to see if any of these people are violating the rule.


           


benefit accepted


 


benefit not accepted


 


requirement satisfied


 


requirement

not satisfied


P

 

not-P

 

Q

 

not-Q

 



Wason selection task with a Precautionary rule.


Here is a problem involving what precautions should be taken in a hazardous situation.  Translated into logical terms, it has the same structure as the social contract and the descriptive rule (but the mind does not "see" it in logical terms...). This precautionary rule elicited the logically correct response -- which is also the response you should make to see if anyone is in danger -- from 76% of UCSB undergraduates.


To see how the mind "sees" this problem, <click here>


Biology labs often study diseases by studying the viruses that cause disease.  Of course, anyone who gets the virus on their skin can get quite sick.  Paragon, Inc. is a drug company that studies diseases.  Some of their labs study viruses, others are just chemical labs where they invent new drugs.  Paragon has a safety rule, “If you work in the lab with viruses, then wear rubber gloves.”


You want to see whether anyone ever breaks this safety rule.


The cards below represent four people who work for Paragon.  Each card represents one person.  One side of the card tells whether that person works in the lab with viruses and the other side tells whether that person is wearing rubber gloves.


Which of the following cards would you definitely need to turn over to see if any of these people are breaking the safety rule:


“If you work in the lab with viruses, then wear rubber gloves.”


Do not turn over any more cards than are absolutely necessary.


 
works in the lab with viruses

 

 
does not work in the lab with viruses

 

 
wearing rubber gloves

 

 
not wearing rubber gloves

 



General Structure of a Precaution Problem


According to hazard management theory (Fiddick, 1998, Fiddick, Cosmides & Tooby, 2000), we have reasoning mechanisms designed to manage the hazards that our hunter-gatherer ancestors would inevitably have encountered.  Their function is to look for situations in which one might be in danger from having not taken an appropriate precaution.


The following rule holds: 

“If  you engage in the hazardous activity, then you must take the precaution.”

(If                             P                              then          Q                      )

 
You want to find out whether this rule is ever violated.  The cards below have information about four people.  Each card represents one person.  One side of a card tells whether a person accepted the benefit, and the other side of the card tells whether that person satisfied the requirement.  Indicate only those card(s) you definitely need to turn over to see if any of these people are violating the rule.


 


engaged in hazardous activity

 


did not engage in hazardous activity

 


took the precaution

 


did not take the precaution

P

 

not-P

 

Q

 

not-Q

 


 

Understanding the difference between a Standard Social Contract and a Switched Social Contract

 

Suppose I said to you,

"If you give me your watch, I will give you $100". 

It woudn't matter if instead I had said,

"If I give you $100, then you give me your watch"


In both cases, I have offered you the exact same social contract

But in the first case, "you give me your watch" corresponds to the logical category P (true antecedent), whereas in the other case it corresponds to the logical category Q (true consequent).


From my point of view -- where I am the potential cheater -- these rules translate as follows:


Standard format:

"If you give me your watch, I will give you $100". 

“If I take the benefit, then I will satisfy the requirement.”

 (If               P                 then           Q                               )


Switched format:

"If I give you $100, then you give me your watch"

“If I satisfy the requirement, then I take the benefit.”  (switched form)

(If               P                             then              Q                  )


Imagine that I had made this offer to four different people.  The cards below have information about what I did with each of these four people.  Each card represents one of these people.  One side of a card tells whether I gave that person $100, and the other side of the card tells whether that person gave me her watch.  Indicate only those card(s) you definitely need to turn over to see if I cheated any of these people.


                                                                                                                    


She gave me her watch

 


I got no watch from this woman

 


I gave this woman $100

 

 


I gave this woman nothing

    

Regardless of how the offer is phrased, to see if I have cheated any of these women you would need to turn over the card that says "She gave me her watch" (the benefit accepted card) and the card that says "I gave this woman nothing" (the requirement not satisfied card). 

 

But notice what logical categories these cards fall into:

 

 

 

Standard format

 

Switched format

Benefit accepted

(She gave me her watch)

P

Q

Requirement not satisfied

(I gave her nothing)

not-Q

not-P

Benefit not accepted

(I got no watch from this woman)

not-P

not-Q

Requirement satisfied

(I gave this woman $100)

Q

P

Correct cheater detection answer (expressed in logical terms) P & not-Q Q & not-P

 

Social contract problems DO NOT activate logical reasoning.  We know this because when given a social contract with a SWITCHED format, people correctly investigate cheaters -- which corresponds to the LOGICALLY INCORRECT answer, Q & not-P.

 

Notice also: A person who was relentlessly logical would fail to detect cheaters, thereby making an adaptive error, on any social contract that was phrased in a switched form.  P & not-Q is the logically correct answer NO MATTER WHAT THE CONTENT OF THE RULE.  This is because logic is content-independent: that is, the same inference rules are applied no matter what the subject matter is.  But for a switched social contract, P & not-Q corresponds to folks who could not possibly have cheated.  If I had given you $100 (satisfied the requirement) without accepting your watch from you (benefit not accepted), I might be a generous person (or a fool), but I have most definitely not cheated you.

 

The mind's definition of cheating is content-dependent: cheating is illicitly taking a benefit (i.e., taking the benefit without having satisfied the requirement).  The cheater detection mechanism investigates these cases, without noticing or caring about what logical category they correspond to.