Agreeableness is a personality trait that manifests as behavior that is perceived as kind, sympathetic, cooperative, warm, frank, and considerate. In contemporary personality psychology, agreeableness is one of the five major dimensions of personality structure, reflecting individual differences in cooperation and social harmony.
People whose measured agreeableness is high are empathetic and altruistic, while those with low agreeableness are prone to selfish behavior (often manifesting as stinginess) and a lack of empathy. Those whose measured agreeableness is very low show signs of dark triad behavior such as manipulation and competing with others rather than cooperating.
Agreeableness is considered to be a superordinate trait, meaning that it is a grouping of personality sub-traits that cluster together statistically. The lower-level traits, or facets that are grouped under agreeableness are: trust, straightforwardness, altruism, compliance, modesty, and tender-mindedness.
As is the case with all Big Five personality traits, the roots of the modern concept of agreeableness can be traced to a 1936 study by Gordon Allport and Henry S. Odbert. Seven years after that study, Raymond Cattell published a cluster analysis of the thousands of personality-related words identified by Allport and Odbert. The clusters identified in this study served as a foundation for Cattell's further attempts to identify fundamental, universal, human personality factors. Cattell eventually determined 16 personality factors (16PF) by means of factor analysis. Further factor analyses revealed five higher-order, or "global", factors that encompass these 16. Although labelled "independence" by Cattell, one of the global factors identified by the 16PF Questionnaire was an early precursor to the modern concept of agreeableness.
Agreeableness in the five factor model of personality is most commonly measured by self-report, although peer-reports and third-party observation can also be used. Self-report measures are either lexical or based on statements.