Experiment by Leda Cosmides
True or false: If a man eats cassava root, then he must have a tattoo on his face.
Which of these men must you check to determine whether the rule is true?
#1 is eating cassava root.#2 is eating molo nuts.
#3 has a tattoo on his face.
#4 has no tattoo on his face.
In terms of the Wason task, this problem looks like this:
In this form, only 21% give the correct response. Not a surprise, because both the Availability and the Social Contract explanations predict poor performance.
But what if subjects are told this before solving the problem?
A tattoo means that a man is married.Cassava root is an aphrodisiac that makes men irresistable to women.
This makes it a social contract situation. Now 75% correct responses.
Psych 391h: Cognitive
Neuroscience 
Kyle Cave
Psychology Dept.
U.
Mass.