Characteristics that differ from one person to another in a continuous and consistent way.
Traits include such personality characteristics as introversion, aggressiveness, generosity, nervousness, and creativity. Systems that address personality as a combination of qualities or dimensions are called trait theories.
The first comprehensive trait theory was that of Gordon Allport (1897-1967). Over a period of thirty years, Allport investigated over 18,000 separate traits, proposing several principles to make this lengthy list manageable for practical purposes. One was the distinction between personal dispositions, which are peculiar to a single individual, and common traits, which can be used for describing and comparing different people. While personal dispositions reflect the individual personality more accurately, one needs to use common traits to make any kind of meaningful assessment of people in relation to each other. Allport also claimed that about seven central traits dominated each individual personality (he described these as the type of characteristic that would appear in a letter of recommendation). Another concept devised by Allport was the cardinal trait—a quality so intense that it governs virtually all of a person's activities (Mother Theresa's cardinal trait would be humanitarianism, for example, while that of the fictional character Ebenezer Scrooge would be avarice). Secondary traits, in contrast, are those that govern less of a person's behavior and are more specific to certain situations.
Using the statistical technique of factor analysis, Raymond B. Cattell reduced Allport's list of traits to a much smaller number and then proceeded to divide these into clusters that express more basic dimensions of personality (for example, the pairs talkative-silent, open-secretive, and adventurous-cautious can all be grouped under the overall source trait of extroversion). Eventually he arrived at 16 fundamental source traits and developed a questionnaire to measure them—the Sixteen Personality Factor Questionnaire (16 PF)—which uses the answers to over 100 yes-or-no questions to arrive at a personality profile.
Hans Eysenck has also proposed a factor-analytic trait model of human personality. However, Eysenck's model focuses on the following three dominant dimensions that combine various related traits: psychoticism (characterized by various types of antisocial behavior), introversion-extroversion, and emotionality/neuroticismstability. Eysenck has also combined the introversion-extroversion and emotionality-stability scales into a model containing four quadrants whose groupings of traits correspond roughly to the four types of personality outlined by the physician Hippocrates over 2,000 years ago in ancient Greece—sanguine, choleric, phlegmatic, and melancholic.
Other trait-oriented theories include those of J.P. Guilford and David McClelland. Currently, a number of psychologists interested in a trait approach to personality believe that the following five factors, rather than Eysenck's three, are most useful in assessing personality: extroversion, agreeableness, conscientiousness, neuroticism, and openness to experience. A questionnaire called the NEO Personality Inventory, often called "the big five," has been developed to assess these factors.
Allport, Gordon W. Personality and Social Encounter: Selected Essays. Boston: Beacon Press, 1960.
Eysenck, Hans. The Structure of Human Personality. London Methuen, 1970.