Overconfidence Effect

The overconfidence effect is a cognitive bias in which someone believes subjectively that his or her judgement is better or more reliable than it objectively is. A common way this bias is studied is by asking people how confident they are in their specific beliefs or in the answers they give to specific questions. After answering questions, the person’s confidence in being correct is compared with whether or not the person actually answered the question correctly. Data collected show that a person’s confidence usually exceeds their objective accuracy, which implies that people can be surer of their answers and abilities than they should be.


See this link for more biases and fallacies.