The tendency to see ourselves as responsible for our successes, but to see other people or the circumstances as responsible for our failures. We reason this way to protect our self-esteem, and to protect our image in the eyes of others. We also do it because it really feels right.
In other words, in a given situation, humans’ self-serving bias causes us to attribute positive outcomes, or successes, to our own individual, internal factors – we tell ourselves, I succeeded in this task because I am smart,or talented, or deserving, et cetera. The same bias causes us to attribute negative outcomes, or failures, to external factors: I failed because my boss didn’t give me clear directions, or my professor didn’t teach in a way I could understand, or the policeman who gave me the speeding ticket was out to get me.
A famous analysis of the self-service bias was published by Anthony Greenwald in the journal American Psychologist in 1980. Dr. Greenwald earned his Ph.D. from Harvard in 1963 and went on to join the faculty at Ohio State and U. of Washington. In his 1980 paper, Greenwald argues that self-serving bias is not merely a way for humans to interpret specific events, it is a fundamental part of the process by which we organize our understanding of the world.
Greenwald’s article is available online here (PDF).