Trait Ascription Bias: Why Others Have Traits and You Have Moods

You have a great deal of information about yourself and much less about anyone else. You have seen yourself in every situation you have ever been in, cheerful and irritable, bold and timid, and you know what each was a response to. You have seen your friend in the situations you share, a narrow slice, without access to their reasons. From the inside, a life looks like a series of situations met with different responses. From the outside, the same life looks like a pattern, and a pattern invites a trait.

Edward Jones and Richard Nisbett proposed this in 1971, in a monograph titled The Actor and the Observer: Divergent Perceptions of the Causes of Behavior, as part of the actor-observer hypothesis. That monograph is not online; this page follows the account of it given in Nisbett, Caputo, Legant and Marecek's 1973 paper, which tested the trait version. College students described themselves, their best friend, their father and a television newscaster on trait pairs, with the option of saying that it depends on the situation. They ascribed more traits to other people than to themselves. The paper also found that observers expected an actor to behave the same way in the future while the actors did not, and that students explained a friend's choice of major in terms of the friend's qualities and their own in terms of the major.

Daniele Kammer separated two things that the trait-pair method confounds. Saying that a trait describes you strongly and saying that your behavior on that trait is consistent are different claims, and Kammer's 1982 study measured them apart. Kammer's 56 participants judged their friends' behavior as more consistent than their own, as the hypothesis predicts, but ascribed stronger traits to themselves than to their friends. Sande, Goethals and Radloff made the same point in 1988 under the name of the multifaceted self: when offered both poles of a trait pair, such as both serious and carefree, participants chose both for themselves more often than for other people.

Two cautions belong here. Bertram Malle's 2006 meta-analysis of the actor-observer asymmetry in causal explanations found the classic effect small on average and dependent on the kind of event; the trait-ascription finding concerns descriptions rather than explanations and was not what that review tested, but readers should expect smaller and more conditional effects than the textbook version suggests. And a gap between the two sliders above is one person's two ratings. It cannot show that you see others as fixed, only that you gave one of two people more variability.

Daniele Kammer's "Differences in trait ascriptions to self and friend: Unconfounding intensity from variability" appeared in Psychological Reports in 1982. The problem it addressed was a weakness in the standard method. In the 1973 studies, participants chose between a trait, its opposite and the option that it depends on the situation, so a participant who felt strongly that they were both outgoing and reserved, in different circumstances, had no way to say so except by choosing the situational option, which was then scored as ascribing no trait. Intensity and variability were tangled together in one answer.

Kammer's method asked for both separately: how intensely a trait applies, and how variable the person's trait-related behavior is. Fifty-six participants described themselves and a friend. Two independent groups provided the actor and observer data, so that one group's self-descriptions could be compared with another group's descriptions of friends without the two being made in the same sitting. The friends' behavior was judged more consistent than the participants' own, in line with the actor-observer hypothesis, and participants ascribed higher trait intensities to themselves than to their friends.

A second set of descriptions, made by the same people of both self and friend, supported the pattern only partly, which Kammer read as a sign that describing yourself and a friend side by side brings social comparison into the judgment as well. The distinction Kammer drew has been the standard way of stating the effect since: the self is not seen as having fewer traits, but as having traits that apply strongly and behavior that varies with the situation, while others are seen as consistent.

Sande, Goethals and Radloff's 1988 paper extended the result across four experiments. Participants who could choose one pole of a trait pair, the other, or both chose both more often for themselves than for others, a self-perception the authors called multifaceted: someone who can be serious or carefree as the situation requires, where other people are one or the other. A person who has seen themselves in more situations has more evidence of variety.

The rows below are illustrations of where one person's variability becomes another person's trait, not findings from the studies cited on this page.

The asymmetry comes from a difference in information and vantage point, so the counters add information and shift the vantage point.

• Ask for the situation before assigning the trait. The question you would answer for yourself, what was going on, is available for other people too.
• Collect more situations. A trait judgment from the one context in which you see someone is a judgment of that context; people who know them elsewhere will have different adjectives.
• Describe behavior, not character, when it matters. A sentence about what someone did in a specific situation is checkable, and it leaves room for them to have done otherwise elsewhere.
• Run the reversal. Describe yourself the way an observer with your friend's information would, and your friend the way they would describe themselves.
• Expect others to change with the room. Nisbett and colleagues found that observers predicted actors would behave the same way again while actors did not.
• Keep the finding in proportion. Malle's meta-analysis is a reminder that the asymmetry is smaller and more conditional than its reputation; the goal is accuracy, not a rule that traits are always wrong.

Trait ascription bias is one of a cluster of self-other asymmetries, and it is defined by the specific contrast between variability for the self and consistency for others.

• It is not the fundamental attribution error, which is the tendency to explain anyone's behavior by their character rather than their circumstances. Trait ascription bias is the self-other asymmetry in that tendency: traits for them, situations for me.
• It is not quite the actor-observer bias either, though it comes from the same 1971 hypothesis. That bias concerns explanations of particular acts; trait ascription bias concerns descriptions of people, and Kammer's point was that the two can come apart.
• It is not the illusion of asymmetric insight, the belief that you understand other people better than they understand you. That is about knowledge of minds; this is about how much variety each mind is granted.
• It is not the out-group homogeneity bias, in which members of other groups are seen as more alike than members of one's own. That operates between groups; trait ascription bias operates between one person and everyone else, friends included.