CHAPTER 14- Personality
Personalitya particular pattern of behaviour and thinking that prevails across time
and situations and differentiates one person from another.
Psychologists do not draw inferences about personality from casual observations
of peoples behaviour but from results of special tests designed to identify
particular personality characteristics. The ultimate goal of psychologists is to
discover the causes of individual differences in behaviour.
What types of research efforts are necessary to study personality?
Research on human personality requires two kinds of effort: identifying
personality characteristics and determining the variables that produce and control
TRAIT THEORIES OF PERSONALITY
Trait theorist use the term in the sense that it is a set of personal characteristics that
determines the different ways we act and react in a variety of situations.
Personality Types and Traits
Humoural theory: proposed by Hippocrates in 4 B.C.E. is the earliest known
explanation for individual differences in personality; based on medical beliefs.
The body was thought to contain four humours (fluids): yellow bile, black bile,
phlegm and blood. People were classified according to disposition.
Choleric people (excess yellow bile) were bad tempered and irritable
Melancholic people (excess black bile) were gloomy and pessimistic
Phlegmatic people (excess phlegm) were sluggish, calm and unexcitable
Sanguine people (excess blood) were cheerful and passionate
The above theory was discredited and the notion of different personality types
different categories into which personality characteristics can be assigned
based on given factorsstood (e.g. Freuds theory of psychosexual stages,
Personality types are useful in formulating hypotheses. After identifying and
defining personality types, one can determine whether these types actually exist
and whether it can lead to valid predictions about ones behaviour in different
Today, individual differences in personality are determined in degree, not kind.
www.notesolution.com Toby and Cosmides (1990) argue that sex produces a reshuffling of genes in
each generation, making it highly unlikely that a single, unified set of genes
related to personality type would be passed from one generation to the next.
Many prefer to measure the degree to which an individual expresses a
personality traitan enduring personal characteristic that reveals itself in a
particular pattern of behaviour in different situations.
Personality traits are not simply patterns of behaviour: they are factors that
underlie these patterns and are responsible for them. Once our personality traits
are developed, they reside in our brains but can be changed. Thus, we carry our
personality traits around with us in our brains.
Identification of Personality Traits
Ultimate goal of the personality psychologists is to explain what determines
Allports Search for Traits
Gordon Allport was one of the first psychologists to search systematically for a basic
core of personality traits; began by identifying all words that described aspects of
personality, analyzed and identified those words that describe only stable personality
characteristics. Why? He believed that extent to which trait labels appear in English
attests to the importance of traits in how people think about themselves and others. He
also believed that people with a particular trait react similarly across situations because
they experience a unique sense of similarity across those situations that guide their
feelings, thoughts and behaviour.
According to Allport, not all traits have equal influences. The most powerful are cardinal
traits which characterize a strong unifying influence on a persons behaviour (rare) and
these kinds of people stood out in a crowd. Central traits are less singular in influence
but capture important characteristics in an individual (e.g. saying someone is warm and
honest in order to distinguish them from others). Secondary traits include characteristics
that have minor influence on the consistency of behaviour (e.g. a persons tendency to
frequently change jobs).
Cattell: Sixteen Personality Factors
Raymond Cattell used Allports list of trait words for this theory of central traits and
shortened the list down to 171 adjectives he believed made up a relatively complete set
of distinct surface traits (observable behaviours). He used factor analysis to identify
clusters that he believed represented underlying traits and eventually identified 16
personality factors and referred to them as source traits since they were the foundations
on which personality developed (Fig. 14.3).
www.notesolution.com Eysenck: Three Factors
Hans Eysenck used factor analysis to devise a theory of personality and identified three
important factors: extroversion, neuroticism, and psychoticism (bipolar dimensions).
Extroversion refers to outgoing nature and a high level of activity. Extroverts generally
like people and socializing, are spontaneous and take risks. Introversion is the
opposite and introverts are usually shy, reserved and careful. People who are at the
high end of neuroticism are fraught with worry and guild, and are moody and unstable.
The opposite is emotional stability and these people are even-tempered. Psychotism
reference to an aggressive, egocentric and antisocial nature whereas self control
refers to a kind and considerate nature, obedient of rules and laws.
Take a look at Table 14.1. Eysenck argued that the most important aspects of a
persons temperament are determined by the combination of the three dimensions of
extroversion, neuroticism, and psychoticism (like colours), see Fig 14.4. He also
emphasized the biological nature of personality and believes that the functioning of a
neural system located in the brain stem produces different levels of arousal of the
cerebral cortex. Consider introverts and extroverts. Introverts have relatively high levels
of cortical excitation while extroverts dont. Thus, in order to maintain the optimum
arousal level, extroverts seek stimulation from external sources by socializing with
The Five-Factor Model
This model proposes that personality is composed of five primary dimensions:
neuroticism, extroversion, openness, agreeableness, and conscientiousness which are
measured by the Neuroticism, Extraversion, and Openness Personality Inventory,
or NEO-PI-R. It consists of 240 items that can potentially be used to describe the
person being evaluated and test items can be answered by the participant or people
they know well.
Is there a biological basic for these five factors? A rapidly accumulating body of
evidence points to a very strong degree of heritability.
Do the five factors predict anything of importance? DeNeve and Cooper (1998) has
shown that the five factors can be used to predict subjective well-being.
Heritability of Personality Traits
www.notesolution.com Cattell and Eysenck have asserted that a persons genetic history has a strong
influence on his or her personality. The heritability of a trait can be assessed by twin-
studies and adoptive studies. Many studies show that identical twins are more similar to
each other than are fraternal twins on a variety of personality measures, indicating
these characteristics are heritable. In fact, Bouchard (1997) found that identical twins
personality traits generally correlated nearly double that of fraternal twins. Results of
such studies suggest that heredity is responsible for between 50 and 70 percent of the
variability in personality traits, thus the remaining 30 to 50 percent of the variability
would be caused by differences in environment.
If family environments have significant effects on personality characteristics, then twins
raised together should be more similar than those raised apart. But they were not. A
study by Zuckerman (1991) suggested that the family environment seem to account for
none of the variability of personality traits in the twins tested.
Heredity and environment can interact and the major source of interaction seems to be
the effect that peoples heredity has on their family environments. In a study where
participants rate their households based on give factors, the identical twins agreed on
their ratings much more than the fraternal twins did. There are two possible
explanations for this: the family environments could have been more similar for identical
twins than for fraternal twins, or the family environments could have really been the
same in all cases but were simply perceived as different by the fraternal twins. The first
possibility is correct. Read following paragraphs on page 458.
Brain Mechanism in Personality
Zuckerman (1991) suggested that personality dimensions of extroversion, neuroticism,
and psychoticism are determined by the neural systems responsible for reinforcement,
punishment, and arousal (e.g. extroverts are highly sensitive to reinforcement).
People who are neurotic are anxious and fearful and if they are psychotic at the same
time, they can be hostile as well. These retards are particularly sensitive to the
punishing effects of aversive stimulus and thus Zuckerman suggests the personality
dimension of neuroticism is controlled by the sensitivity of the neural system responsible
for punishment (involves the amygdala).
People who are psychotic have difficulty learning when not to do something. They have
a low sensitivity to punishment a