A study by Nisbett et al. (1973) demonstrates the actor-observer bias by examining how men explain romantic attraction. When asked to explain their own attraction (the 'actor' role), participants predominantly cited situational factors, such as their girlfriend's positive personality traits. They rarely mentioned their own dispositional traits, like a personal need for companionship. However, when explaining a friend's attraction (the 'observer' role), participants gave roughly equal weight to both situational factors (the friend's girlfriend's traits) and dispositional factors (the friend's internal traits). As illustrated in the accompanying graph, actors strongly favor external explanations for their own behavior, whereas observers use a more balanced approach when explaining others' behavior.