“Everyone is responsible for their own behaviour… Except me!”
Actor-observer bias refers to our tendency to attribute external causes to our own behaviour and to attribute internal causes to the behaviour of others . Thus, when explaining our own actions, we will tend to call on aspects of the situation (difficulty of the task, chance, etc.), rather than personal elements (effort provided, personality, etc.). Conversely, and consistent with the fundamental attribution error, when we observe the behaviour of another person, we tend to explain that behaviour through the characteristics of the person being observed, rather than the situation. This difference in interpretation between the actor and the observer can therefore lead to misunderstandings and cause problems in interpersonal relationships. It can also manifest itself at the level of relations between groups: we attribute external causes to the negative behaviours of members of our own group and internal causes to the negative behaviours of members of another group (see the ultimate attribution error) .
For a long time, the actor / observer bias was considered to be a firmly established and widespread bias in the population. A 2006 meta-analysis, however, called into question the results of previous studies. In particular, it seems that this bias is only present when the behaviour is negative .
John crashes into the back of Simone's car, which was stopped at a red light. Enraged, Simone gets out of her vehicle. Walking towards John, Simone, here the observer, shouts: "What a bad driver you are! How could you pass your driver’s license test if you are unable to pay attention to what is happening in front of you?” She therefore presumes, from the information she has, that John is an incompetent driver and an inattentive person. Faced with Simone's accusatory comments, John replies: “I dozed off for a moment, but obviously, I can drive! I had to work in the hospital all night, because my replacement never came. Besides, I had no choice but to get behind the wheel, since I have to pick up my daughter from the station.” Thus, knowing his driving abilities in general and the details of the situation, John, here the actor, explains having caused an accident by the circumstances in which he finds himself.
The main hypothesis to explain this bias is the lack of information available to the observer, who does not know how the actor acts in different contexts. The observer therefore bases their idea of the person on the observed behaviour. As such, the more the pair gets to know each other, the less the bias will be present. In addition, situational elements are in the forefront for the person taking action. Indeed, unlike the observer, the actor does not pay attention only to their own behaviour and personal characteristics, focusing instead on the circumstances and/or their environment .
Another hypothesis is that a person tries to protect their self-esteem by explaining their negative behaviours by causes external to them and their positive behaviours by internal causes (see the self-serving bias) . This would explain why the actor-observer bias only seems to concern negative behaviour.
This bias implies a divergence in perception which can cause misunderstandings  and even interpersonal conflicts . It can also lead to self-fulfilling prophecies, since attributing internal causes to an individual's behaviour creates expectations which pushes us to act towards that individual in a way that confirms those expectations . For example, if a teacher believes that a student's academic failure is due to their low intellectual level, the teacher may stop providing additional help. The student will continue to have difficulty, which will confirm the teacher's opinion about them.
Thoughts on how to act in light of this bias
Try to put yourself in their shoes when judging the behaviour of others.
In the role of an actor, think about what you could have done differently in the same situation.
Talk with the actor or actress to understand their action.
How is this bias measured?
Actor-observer bias can be measured in different ways. For instance, scientists can look at the causes attributed to a behaviour by people in the observer role, and by people producing the behaviour. To do this, participants can recall a situation they have experienced in their personal life, imagine a hypothetical situation or judge a behaviour taking place in the context of the experiment. The scientists then compare the type of causes mentioned (internal or external) according to the role assumed (actor or observer). If individuals mention more external causes when they explain their own behaviours (as actors) than when they explain those of others (as observers), we can conclude that the bias is present.
This bias is discussed in the scientific literature:
This bias has social or individual repercussions:
This bias is empirically demonstrated:
 Jones, Edward E. (1976). How Do People Perceive the Causes of Behavior? Experiments based on
 Jones, Edward E. & Richard E. Nisbett (1971). The actor and the observer: Divergent perceptions
of the causes of behavior. General Learning Press.
 Malle, Bertram F. (2006). The Actor–Observer Asymmetry in Attribution: A (Surprising) Meta-
Analysis. Psychological Bulletin, 132(6), 895–919. DOI : 10.1037/0033-2909.132.6.895
 Thomas, F. (1979). The Ultimate Attribution Error: Extending Allport's Cognitive Analysis of Prejudice. Personality and Social Psychology Bulletin 5(4), 461-476. DOI: 10.1177/014616727900500407
 Rascle, Olivier, Alan Traclet & Geneviève Coulomb-Cabagno (2005). Le biais attributionnel acteur/observateur en contexte sportif. Dans Olivier Rascle et Philippe Sarrazin (dir.). Croyances et performances sportives : Processus sociocognitifs associés aux comportements sportifs (pp. 207-226). Editions EP&S. : BIB_2BB1765103A8.P001/REF
Representativeness heuristic, Availability heuristic, Need for self-esteem, Need for cognitive closure, Interpersonal level
Marie Taillefer, Bachelor student in psychology, Université de Montréal.
Translated from French to English by Eric Muszynski.