Wason Selection Task

Devised in 1966 by Peter Cathcart Wason, the Wason selection task, one of the most famous tasks in the psychology of reasoning, is a logic puzzle which most people get wrong. An example of the puzzle is:

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?

A response that identifies a card that need not be inverted, or that fails to identify a card that needs to be inverted, is incorrect. Note that the original task dealt with numbers (even, odd) and letters (vowels, consonants).

Evolutionary psychologists have gathered experimental evidence that people find the Wason task much easier if it is placed in the context of a social rule that the experimental subject is asked to police, suggesting that humans solve the social-rule problem with a specialized mental module that evolved to catch cheaters in a social environment.

The reader must be aware that the importance of the experiment is not in justifying one answer of the ambiguous problem, but in demonstrating the inconsistency of applying the logical rules by the people when the problem is set in two different contexts but with very similar connection between the facts.