Overconfidence Effect

The overconfidence effect is a well-established bias in which someone's subjective confidence in their judgments is reliably greater than their objective accuracy, especially when confidence is relatively high. For example, in some quizzes, people rate their answers as "99% certain" but are wrong 40% of the time. It has been proposed that a metacognitive trait mediates the accuracy of confidence judgments, but this trait's relationship to variations in cognitive ability and personality remains uncertain. Overconfidence is one example of a miscalibration of subjective probabilities.