Trait ascription bias is the tendency for people to view themselves as relatively variable in terms of personality, behavior and mood while viewing others as much more predictable in their personal traits across different situations. More specifically, it is a tendency to describe one’s own behavior in terms of situational factors while preferring to describe another’s behavior by ascribing fixed dispositions to their personality. This may occur because peoples’ own internal states are more readily observable and available to them than those of others.
This attributional bias intuitively plays a role in the formation and maintenance of stereotypes and prejudice, combined with the negativity effect. However, trait ascription and trait-based models of personality remain contentious in modern psychology and social science research. Trait ascription bias refers to the situational and dispositional evaluation and description of personality traits on a personal level. A similar bias on the group level is called the out-group homogeneity bias.