A friend of yours has never taken a psychology course before. You show her four
cards labeled P, 7, E, 4, and ask her which cards need to be turned over to verify the
rule "If there is a consonant on the front, then there is an odd number on the back."
The correct answer is to turn over the cards labeled "P" and "4", but your friend
foolishly turns over cards labeled "P" and "7". You reassure her that most people
make this mistake, which is known as (a/an):
