proceed from that point. We will, of course, need to return to this issue
when we formulate a trait theory of personality .
Similarly , we need not understand the physiological basis of traits
in order to chart their development in later life. Most contemporarypsychologists would acknowledge that there must be some neuro -
physiological or hormonal basis for personality , and some specific
mechanisms have been proposed (e.g., Cloninger, Svrakic, & Przybeck,1993). But to date the evidence in favor of these theories is limited, andit is unlikely that we will ever find a specific region of the brain thatcontrols Neuroticism, or a neurotransmitter that accounts for Extraver -
sion, or a single gene for Openness. The trait names do not refer to the
underlying physiology but to the abstract consistencies in the ways peo -
ple act and experience and to whatever complex psychological causes
they may have.
How Many Traits? Which Ones?
Any number of human characteristics fit the definition of traits. Thereare physical traits ( tall,healthy ), ability traits ( intelligent ,musical ), and
social traits ( rich,famous ). Our interest is in personality traits, which
describe emotional, interpersonal, experiential, attitudinal, and motiva-tional styles. One way to get a sense of the scope and variety of person-ality traits is by consulting the dictionary: The English language pro-vides an embarrassment of riches to the trait psychologist. So importantare descriptions of people that thousands of terms have evolved, distin-guishing minute shades of meaning that delight the poet and confoundthe empirical scientist. One major approach to personality has focusedon analyses of natural language trait terms (John, Angleitner, & Osten -
dorf, 1988).
The more common alternative has been to begin with psychologi -
cal theory and the insights of trained clinicians and researchers. After
all, we do not expect chemists or anatomists to base their taxonomieson lay terminology , and many psychologists have disdained the com -
mon vocabulary of traits.
Theories of particular characteristics have often lead to the devel -
opment of trait measures; hundreds of scales have been created in this
way . Rokeach (1960) developed a questionnaire to measure his conceptof dogmatism, and Crandall (1981) proposed a trait preference list toassess Alfred Adler’s (1938/1964) concept of social interest. There areA Trait Approach to Personality 29