What is the tendency to attribute ones own behavior to external, situational causes, while attributing the behavior of others to internal, personal causes?

This is an area within social psychology called Fundamental Attribution Theory (FAE). Assigning blame or self blame to actions is of obvious interest within the field of criminology, too, for those accused must answer for who or what they assert is the cause of their criminal act. This area of psychological enquiry reveals that observers are often quicker to attribute cause of an action to an individual, even when that action or outcome is positive, than to situational factors.

In one experiment, observers stated that questioners had higher intelligence than answerers when questioners had advance knowledge of the questions, and answerers none. The situational factor had been neglected. We are typically more ready to believe that we are responsible for our success, but other factors more responsible for our failures.