Biological Trait Theories

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TA B L E
Chapter 11 Personality
11.2
The Big-Five Personality
Dimensions
Here is a list of the adjectives that define
the big-five personality factors. You can
more easily remember these factors by noting that the first letters of their names spell
the word ocean.
Dimension
Defining Descriptors
Openness
Artistic, curious, imaginative, insightful, original, wide
interests, unusual thought processes, intellectual interests
Conscientiousness
Efficient, organized, planful, reliable, thorough, dependable,
ethical, productive
Extraversion
Active, assertive, energetic, outgoing, talkative, gesturally
expressive, gregarious
Agreeableness
Appreciative, forgiving, generous, kind, trusting, noncritical,
warm, compassionate, considerate, straightforward
Neuroticism
Anxious, self-pitying, tense, emotionally unstable,
impulsive, vulnerable, touchy, worrying
Source: Adapted from McCrae & John (1992).
Allport’s research helped to lay the foundation for modern research on personality
traits. However, his focus on the uniqueness of each personality made it difficult to
draw conclusions about the structure of personality in general. In contrast, British psychologist Raymond Cattell was interested in the personality traits that people share. He
used a mathematical technique called factor analysis to study which traits are correlated
with one another. Factor analysis can reveal, for example, whether people who are
moody are also likely to be anxious, rigid, and unsociable. Cattell found sixteen clusters of traits that he believed make up the basic dimensions, or factors, of personality
(Cattell, Eber, & Tatsuoka, 1970).
The Big-Five Model of Personality
big-five model A view based on
factor-analytic studies suggesting the
existence of five basic components of
human personality: openness, conscientiousness, extraversion, agreeableness,
and neuroticism. Also called the fivefactor model.
Building on the work of Allport and Cattell, today’s trait theorists use factor-analytic
techniques to bring the structure of personality into even sharper focus. The results of
their research have led many of these theorists to conclude that personality is organized
around just five basic factors (McCrae & Costa, 2004). The components of this bigfive model, or five-factor model, of personality have been given slightly different
labels by different researchers, but the most widely used names are openness, conscientiousness, extraversion, agreeableness, and neuroticism (see Table 11.2). The fact that
some version of the big-five factors reliably appear in many countries and cultures—
including Canada, China, the Czech Republic, Germany, Greece, Finland, India, Japan,
Korea, the Philippines, Poland, and Turkey (Allik & McCrae, 2004; Ashton et al., 2004;
McCrae et al, 2004; Saucier et al., 2005)—provides evidence that these factors may
indeed represent the most important components of human personality (McCrae &
Terracciano, 2005).
The emergence of the big-five model is considered by many trait theorists to be a
major breakthrough in examining the personalities of all people, regardless of where
they live or the nature of their economic, social, and cultural backgrounds (Carver &
Scheier, 2004) The big-five model also allows researchers to precisely describe the similarities and differences in people’s personalities and to explore how these factors are
related to everything from personality disorders and political beliefs to substance abuse,
happiness, and a sense of well-being (DeNeve, 1999; Lynam & Widiger, 2001; Roberts &
Bogg, 2004; Van Hiel & Merviedle, 2004).
Biological Trait Theories
Some personality theorists are interested not only in what traits form the core of human
personality but also in why people differ on these traits. Their research suggests that
differences in traits might be due to biological factors.
The Trait Approach
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ANIMAL PERSONALITIES The idea
that personality can be described in terms
of five main dimensions seems to hold
for some animals, as well as humans. The
five animal dimensions differ from, but
are still related to, human traits. For
example, hyenas differ among themselves in terms of dominance, excitability,
agreeableness (toward people), sociability (toward each other), and curiosity.
Some of these same traits have been observed in a wide variety of other species,
including dogs, horses, orangutans, and
chimpanzees (Gosling, 2001; Gosling,
Kwan, & John, 2003; King, Weiss, &
Farmer, 2005; Weiss, King, & Perkins,
2006). Cat lovers often report such traits
in their pets, too.
LINKAGES
Why do some people take
more risks than others?
(a link to Motivation and
Emotion)
Eysenck’s Biological Trait Theory The biological basis for personality was
emphasized in the work of British psychologist Hans Eysenck (pronounced “eye-sink”).
Like other trait theorists who helped lay the groundwork for the big-five model,
Eysenck used factor analysis to study personality. His research led him to focus on two
main personality dimensions known as introversion-extraversion and emotionalitystability (Eysenck, 1990a, 1990b):
1. Introversion-extraversion. Extraverts are sociable and outgoing, enjoy parties
and other social activities, take risks, and love excitement and change. Introverts
tend to be quiet, thoughtful, and reserved, enjoying solitary pursuits and avoiding excitement and social involvement.
2. Emotionality-stability. At one extreme of this dimension are people who exhibit
such characteristics as moodiness, restlessness, worry, anxiety, and other negative
emotions. People at the opposite end are calm, even-tempered, relaxed, and emotionally stable. (This dimension is also often called neuroticism.)
According to Eysenck, personality can be described in terms of where a person falls
along these two dimensions. For example, an introverted but stable person is likely to
be controlled and reliable. An introverted but emotional person is likely to be rigid and
anxious (see Figure 11.3).
Eysenck argued that the variations in personality characteristics that we see among
individuals can be traced to inherited differences in their nervous systems, especially in
their brains. These biological differences, he said, create differences in people’s typical
levels of physiological arousal and in their sensitivity to stress and other environmental stimulation. For example, people who inherit a nervous system that normally operates below some ideal level of arousal will always be on the lookout for excitement,
change, and social contact in order to increase their arousal. As a result, they will be
extraverted. In contrast, people whose nervous system is normally “overaroused” will
tend to avoid excitement, change, and social contact in order to reduce arousal to their
ideal level. In short, they will be introverted. What about the emotionality-stability
dimension? Eysenck said that people who fall toward the stability side have nervous
systems that are relatively insensitive to stress; those who are more emotional have nervous systems that react more strongly to stress.
Gray’s Approach-Inhibition Theory Jeffrey Gray, another British psychologist,
agrees with Eysenck about the two basic dimensions of personality but offers a different explanation of the biological factors underlying them (Gray, 1991). According to
Gray, differences among people in introversion-extraversion and emotionality-stability