Ultimate Attribution Error
The Ultimate Attribution Error was coined by psychologist Thomas Pettigrew in 1979 to explain why members of the ingroup (“us”) tend to judge members of the outgroup (“them”) so harshly. Pettigrew suggested that when outgroup members behave negatively or undesirably, ingroup members attribute their behavior to dispositional causes, such as genetics, poor character, or poor upbringing, whereas when outgroup members behavior positively, ingroup members attribute that behavior to luck, a special privilege, extreme effort, or some other exception to the rule.
When individuals of the ingroup evaluate their own group members, they are more forgiving and make more exceptions for failures and fewer exceptions for successes. This error in thought plays a large role in prejudice and other social biases.
See also: Fundamental Attribution Error