A cognitive bias refers to a systematic error in the thinking process, of which there are many. For example, confirmation bias involves favoring ideas that confirm preexisting beliefs. The Dunning-Kruger effect occurs when people with a low level of knowledge in a given domain overestimate their knowledge or ability. The self-serving bias is the tendency to attribute successes to one’s actions and attribute failures to external circumstances.
Other common biases include the hindsight bias, the negativity bias, the sunk cost fallacy, the decline bias, the backfire effect, the fundamental attribution error, the in-group bias, and the Barnum effect.