Dunning-Kruger Effect
The Dunning-Kruger Effect is a cognitive bias in which people with limited knowledge or skill in a domain overestimate their competence, while experts tend to underestimate theirs. Documented by David Dunning and Justin Kruger (Cornell, 1999), it explains why novices are often more confident than intermediate learners, why self-assessment is unreliable, and why the most dangerous decisions are sometimes made by people with just enough knowledge to feel confident.
Overconfidence Bias
Overconfidence Bias is the tendency to have excessive confidence in the accuracy of one's own answers, judgments, and predictions — being more certain than the evidence warrants. One of the most consistently documented biases in psychology and behavioural economics, it manifests in three forms: calibration overconfidence (confidence intervals too narrow), better-than-average effect (rating oneself above average), and illusion of control (overestimating influence over outcomes).