Errors in Logic

In the basic Wason task, you are testing a rule of the form "If P, then Q"

"If there is a place name on the front, there is a letter on the back."

P = place name

Q = letter

The four cards correspond to the four different types of information you can have in solving this problem.

The rules of logic tell us that in order to properly test this type of rule, we must test "P" and "not Q". The other two categories, "Q" and "not P", are not relevant to the truth of the rule.

In the basic version of this task, 25% or less usually respond correctly.

Many subjects leave out the "not Q" response, and many include the "Q" response.

 

The structure of the drinking age problem is exactly the same.

Yet 75% usually respond correctly to this problem. Why do so many get the drinking problem correct while getting the basic problem wrong?

Psych 391h: Cognitive Neuroscience Kyle Cave Psychology Dept. U. Mass.