Hans Eysenck’s biography and Trait Theory of Personality will discuss every detail in this article. Hans Eysenck (pronounced Eye-Zinc) was born in Germany on March 4, 1916. His parents were actors who divorced when he was only two, and so Hans was raised by his grandmother. He left there when he was 18 years old when the Nazis came to power. As an active Jewish sympathizer, his life was in danger.
In England, he continued his education and received his Ph.D. in Psychology from the University of London in 1940. During World War II, he served as a psychologist at an emergency hospital, where he did research on the reliability of psychiatric diagnoses. The results led him to a life-long antagonism to main-stream clinical psychology.
After the war, he taught at the University of London, as well as serving as the director of the psychology department of the Institute of Psychiatry, associated with Bethlehem Royal Hospital. He has written 75 books and some 700 articles, making him one of the most prolific writers in psychology. Eysenck retired in 1983 and continued to write until his death on September 4, 1997.
Introduction of Hans Eysenck’s Trait Theory of Personality
Temperament is that aspect of our personalities that is genetically based, inborn, there from birth, or even before. That does not mean that a temperament theory says we don’t also have aspects of our personality that are learned! They just have a focus on “nature,” and leave “nurture” to other theorists!
The issue of personality types, including temperament, is as old as psychology. In fact, it is a good deal older. The ancient Greeks, to take the obvious example, had given it considerable thought, and came up with two dimensions of temperament, leading to four “types,” based on what kind of fluids (called humors) they had too much or too little of. This theory became popular during the middle ages.
In describing his theory of personality, Eysenck readily acknowledged that the model that culminated in his own work was a structure that had been built by several bricklayers who had contributed to the slow, steady process of research into temperament and personality (1981).
One of the earliest efforts to describe personality in terms of dispositions was made by the Greek physician Hippocrates (ca. 460–377 B.C.), who suggested that personalities could be classified according to a predominance of certain body fluids, or humors, which reflected the four elements of the cosmos.
Twenty-one hundred years later, Immanuel Kant, a German philosopher (1724–1804), updated and popularized Hippocrates’ doctrine of the four temperaments in his Anthropologie. He organized them according to two basic comparisons: feelings and activity. Melancholic represented weak feelings; sanguine, strong feelings. Phlegmatic represented weak activity; choleric, strong activity.
The sanguine type is cheerful and optimistic, pleasant to be with, comfortable with his or her work. According to the Greeks, the sanguine type has a particularly abundant supply of blood (hence the name sanguine, from sanguis, Latin for blood) and so also is characterized by a healthful look, including rosy cheeks.
The choleric type is characterized by a quick, hot temper, often an aggressive nature. The name refers to bile (a chemical that is excreted by the gallbladder to aid in digestion). Physical features of the choleric person include a yellowish complexion and tense muscles.
Next, we have the phlegmatic temperament. These people are characterized by their slowness, laziness, and dullness. The name obviously comes from the word phlegm, which is the mucus we bring up from our lungs when we have a cold or lung infection. Physically, these people are thought to be kind of cold, and shaking hands with one is like shaking hands with a fish.
Finally, there’s a melancholy temperament. These people tend to be sad, even depressed, and take a pessimistic view of the world. The name has, of course, been adopted as a synonym for sadness, but comes from the Greek words for black bile. Now, since there is no such thing, we don’t quite know what the ancient Greeks were referring to. But the melancholy person was thought to have too much of it!
Eysenck spent most of his career at the University of London’s Maudsley Hospital and Institute of Psychiatry, conducting research on the measurement of personality. He agreed with Cattell that personality is composed of traits, or factors, derived by the factor-analytic method. However, Eysenck was also a critic of factor analysis and of Cattell’s research because of the potential subjectivity in the technique and the difficulty in replicating Cattell’s findings. Although Eysenck used factor analysis to uncover personality traits, he supplemented the method with personality tests and experimental studies that considered a wide range of variables.
A Joint Effort
Eysenck and his second wife, Sybil (Ph.D., University of London), together developed many of the questionnaires used in their research (Furnham, Eysenck, & Saklofske, 2010). The Eysenck Personality Inventory (Eysenck & Eysenck, 1963) required 12 years of joint research and 20-factor analyses. Hans Eysenck wrote, “Although published in our joint names, [it] is largely a monument to her skill, patience, and endurance” (1980, p. 172). Few scientists in any discipline have been so straightforward in acknowledging the research contributions of their spouses.
The structure of personality
Three Dimensions of Personality or Eysenck’s Trait Theory of Personality
The result of their efforts is a personality theory based on three dimensions, defined as combinations of traits or factors. We might think of the dimensions as super factors (Eysenck, 1990a, 1990b; Eysenck & Eysenck, 1985). The three personality dimensions are:
N—Neuroticism versus emotional stability
P—Psychoticism versus impulse control (or superego functioning)
Eysenck noted that the dimensions of extraversion and neuroticism have been recognized as basic elements of personality since the time of the ancient Greek philosophers.
Eysenck (1997) also suggested that formulations of the same dimensions could be found on nearly every personality assessment device ever developed. The Eysenck Personality Inventory has since been used with great success in translated forms in nearly 40 countries, including those as diverse as Italy and Kuwait (see Abdel-Khalek, 2012; Dazzi, 2011).
Consider the list of personality traits associated with Eysenck’s three personality dimensions. You can see clearly, for example, that people who score high on the traits of the E dimension would be classified as extraverts, whereas people who score low would be classified as introverts.
Stability over Time
The traits and dimensions Eysenck proposed tend to remain stable throughout the life span despite our different social and environmental experiences. Our situations may change but the dimensions remain consistent. For instance, the introverted child tends to remain introverted through adolescence and into adulthood (see Ganiban, Saudino, Ulbricht, Neiderhiser, & Reiss, 2008). Other studies in England and the Scandinavian countries confirm the stability over time of Eysenck’s dimensions, particularly extraversion and neuroticism (Billstedt et al., 2014; Gale, Booth, Mottus, Kuh, & Deary, 2013).
The Role of Intelligence
Eysenck also conducted considerable research on intelligence. Although he did not list intelligence as a personality dimension, he considered it an important influence on personality. He noted that a person with an IQ of 120, which is high, is likely to have a more complex and multidimensional personality than a person with an IQ of 80. His research also suggested that some 80 percent of our intelligence is inherited, leaving only 20 percent as the product of social and environmental forces (Eysenck & Eysenck, 1985).
Based on your own experience, you can probably describe most extraverts and introverts pretty accurately. Extraverts are oriented toward the outside world, prefer the company of other people, and tend to be sociable, impulsive, adventurous, assertive, and dominant.
In addition, people who score high in extraversion on the Eysenck Personality Inventory have been found to experience more pleasant emotions and to be happier than those who score low in extraversion (Fisher & Francis, 2013; Holder & Klassen, 2010; Lucas & Fujita, 2000). Extraverted businessmen have been shown to be much better at performing difficult tasks than introverted businessmen (Campbell, Alana, Davalos, McCabe, & Troup, 2011).
Eysenck was interested in how extraverts and introverts might differ biologically and genetically. He found that extraverts have a lower base level of cortical arousal than introverts do. Because the cortical arousal levels for extraverts are low, they need, and actively seek, excitement and stimulation. In contrast, introverts shy away from excitement and stimulation because their cortical arousal levels are already high (Eysenck, 1990b).
As a result, introverts react more strongly than extraverts to sensory stimulation. Studies have shown that introverts exhibit greater sensitivity to low-level stimuli and have lower pain thresholds than extraverts. Other research supports differential responses to sensory stimulation but reports less convincing evidence that such differences can be attributed to variations in cortical arousal levels (Bullock & Gilliland, 1993; Hagemann & Naumann, 2009; Stelmack, 1997). Nevertheless, as Eysenck predicted, these differences are genetically based.
Neurotics are characterized as anxious, depressed, tense, irrational, and moody. They may also have low self-esteem and be prone to guilt feelings. Eysenck suggested that neuroticism is largely inherited, a product of genetics rather than learning or experience.
Research on 16- to 70-year-old Americans conducted over a 2-year period showed that increasing satisfaction gained from work and social relationships was associated with a lower level of neuroticism and a higher level of extraversion (Scollon & Diener, 2006). Studies in Australia found that people who scored high in neuroticism on the Eysenck Personality Inventory outperformed those who scored low when their work environment was fast-paced and stressful. In other words, neurotics seem to function best in busy situations where they were forced to work harder (Smillie, Yeo, Furnham, & Jackson, 2006).
A study in England showed that people high in neuroticism scored lower in verbal abilities than did people low in neuroticism (Chamorro-Premuzic, Furnham, & Petrides, 2006). And research on people in Sweden found that those who scored high in neuroticism in middle age were much more likely to show cognitive impairments when tested again 25 years later (Crowe, Andel, Pedersen, Fratiglioni, & Gatz, 2006).
People high in neuroticism have greater activity in the brain areas that control the sympathetic branch of the autonomic nervous system. This is the body’s alarm system, which response to stressful or dangerous events by increasing breathing rate, heart rate, blood flow to the muscles, and release of adrenaline. Eysenck argued that in neurotics, the sympathetic nervous system overreacts even to mild stressors, resulting in chronic hypersensitivity.
This condition leads to heightened emotionality in response to almost any difficult situation. Indeed, neurotics react emotionally to events other people consider insignificant. According to Eysenck, these differences in biological reactivity on the neuroticism dimensions are innate. People are genetically predisposed either toward neuroticism or toward emotional stability.
People who score high in psychoticism are aggressive, antisocial, tough-minded, cold, and egocentric. Also, they have been found to be cruel, hostile, and insensitive to the needs and feelings of others. In addition, they score low on emotional well-being and have greater problems with alcohol, drug abuse, and violent criminal behavior than people who score low in psychoticism (Boduszek, Shevlin, Adamson, & Hyland, 2013; Ciarrochi & Heaven, 2007; Sher, Bartholow, & Wood, 2000).
Paradoxically, people who score high in psychoticism can also be highly creative. The research evidence tends to suggest a large genetic component. However, it has also been found that those who scored high in psychoticism had more authoritarian and controlling parents than those who scored low, thus supporting the potentially harmful influence of the childhood environment (Heaven & Ciarrochi, 2006).
Men generally tend to score higher on psychoticism than women, which led Eysenck to suggest that psychoticism may be related to male hormones. He also speculated that people who score high on all three dimensions may be apt to display criminal behavior but cited only modest empirical support for this idea (Eysenck & Gudjonsson, 1989).
Research conducted in China has demonstrated a significant positive correlation between criminal behavior and high scores on both the psychoticism and neuroticism dimensions (Huo-Liang, 2006).
Eysenck believed that society needs the diversity provided by people characterized by all aspects of these three personality dimensions. An ideal society affords people the opportunity to make the best use of their traits and abilities. However, some people will adapt to the social environment better than others will.
The person high in psychoticism, for example, typified by hostile and aggressive behaviors, may become emotionally disturbed, or exhibit criminal tendencies, or channel the aggressive traits into a socially acceptable enterprise such as coaching college football.
The Primary Role of Heredity
To Eysenck, traits and dimensions are determined primarily by heredity, although the research evidence shows a stronger genetic component for extraversion and neuroticism than for psychoticism. Eysenck did not rule out environmental and situational influences on personality, such as family interactions in childhood, but he believed their effects on personality was limited (Eysenck, 1990a).
His research design involved comparisons of identical (monozygotic) and fraternal (dizygotic) twins. The studies showed that identical twins are more alike in their personalities than are fraternal twins, even when the identical twins were reared by different parents in different environments during childhood. Studies of adopted children demonstrate that their personalities bear a greater similarity to the personalities of their biological parents than of their adoptive parents, even when the children had no contact with their biological parents. This is additional support for Eysenck’s idea that personality owes more to our genetic inheritance than to our environment.
Cross-cultural research demonstrates that Eysenck’s three personality dimensions have been found consistently in more than 35 nations including the United States, England, Australia, Japan, China, Nigeria, and Sweden (see, for example, Bouchard, 1985; Eaves, Eysenck, & Martin, 1989; Floderus-Myrhed, Pedersen, & Rasmuson, 1980; Hur, 2009; Martin & Jardine, 1986; Tellegen, Lykken, Bouchard, Wilcox, Segal, & Rich, 1988). The confirmation of the same three personality dimensions in diverse cultures is further evidence for the primacy of inherited factors in the shaping of personality.
References: Schultz, D. P., & Schultz, S. E. (2017). Theories of personality (5th ed.), Australia: Cengage Learning.