In social psychology, fundamental attribution error (FAE), also known as correspondence bias or attribution effect, is a cognitive attribution bias where observers underemphasize situational and environmental factors for the behavior of an actor while overemphasizing dispositional or personality factors. This effect has been described as "the tendency to believe that what people do reflects who they are"; that is, to overattribute their behaviors to their personality and underattribute them to the situation or context. Although personality traits and predispositions are considered to be observable facts in psychology, the fundamental attribution error is an error because it misinterprets their effects.

As an example of the behavior which attribution error theory seeks to explain, consider the situation where Alice, a driver, is cut off in traffic by Bob. Alice attributes Bob's behavior to his fundamental personality; e.g., He thinks only of himself, he is selfish, he is an unskilled driver. She does not think it is situational; e.g., He is going to miss his flight, his wife is giving birth at the hospital, his daughter is convulsing at school. Alice might well make the opposite mistake and excuse herself by saying she was influenced by situational causes; e.g., I am late for my job interview, I must pick up my son for his dental appointment, rather than thinking she has a character flaw.