Knowing with certainty: The appropriateness of extreme confidence.

How often are people wrong when they are certain that they know the answer to a question ? The studies reported here suggest that the answer is too often. For a variety of general-knowledge questions (e.g., absinthe is a a liqueur or b a precious stone), subjects first chose the most likely answer and then indicated their degree of certainty that the answer they had selected was, in fact, correct. Across several different question and response formats, subjects were consistently overconfident. They had sufficient faith in their confidence judgments to be willing to stake money on their validity. The psychological bases for unwarranted certainty are discussed in terms of the inferential processes whereby knowledge is constructed from perceptions and memories.