Eysenck's Personality Traits and Genetics Connection
Behavioural Genetics explores the link between genetics and personality, with Eysenck's research focusing on traits like extraversion, neuroticism, and psychoticism. These traits tend to be relatively stable over time and are believed to have a significant genetic component. Eysenck's work has influenced personality psychology globally, with the Eysenck Personality Inventory being widely used to assess personality dimensions. The impact of intelligence on personality is also considered, with higher IQ individuals likely exhibiting more complex personalities.
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Presentation Transcript
Eysencks Behavioural Genetics & McCrae- Costa s Five Factor Model PERSONALITY PSYCHOLOGY
Basic Premises Behavioural Genetics Meaning the connection between genetics and personality, so that significant amount of our personality is determined by genetics component. Eysenck 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
Dimensions of personality (Eysenck & Eysenck 1963) The three dimensions as superfactors (Eysenck, 1990a, 1990b; Eysenck & Eysenck, 1985). E Extraversion versus introversion N Neuroticism versus emotional stability P Psychoticism versus impulse control (or superego functioning) 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). 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. The formulations of the same dimensions could be found on nearly every personality assessment device ever developed.
Dimensions of personality (Eysenck & Eysenck 1963) Stability over time The traits and dimensions Eysenck proposed tend to remain stable throughout the lifespan despite our different social and environmental experiences. 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). Does intelligence influence one s personality? Eysenck 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).
Extraversion Extraverts are oriented toward the outside world, prefer the company of other people, and tend to be sociable, impulsive, adventurous, assertive, and dominant. 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 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). 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.
Neuroticism Neuroticism is largely inherited, a product of genetics rather than learning or experience. 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 responds 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 dimension are innate. People are genetically predisposed either toward neuroticism or toward emotional stability. Studies in Australia found that people who scored high in neuroticism on the EPI outperformed those who scored low when their work environment was fast-paced and
Psychoticism 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 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.
The Role of Heredity 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 were limited. 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. 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. 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.
Robert McCrae and Paul Costa Five- Factor Model Using the factor-analytic method, the personality traits Cattell and Eysenck derived varied in number. This does not indicate an inherent weakness in the method but instead reflects the way each theorist chose to measure personality. Some more recent personality researchers have expressed dissatisfaction with both theories, suggesting that Eysenck had too few dimensions (three) and Cattell had too many factors (sixteen). Robert McCrae (1949 ) and Paul Costa (1942 ) embarked on an extensive research program starting in the 1980s that identified five so-called robust or Big Five factors (McCrae & Costa, 1985b, 1987). These factors are neuroticism, extraversion, openness, agreeableness, and conscientiousness. More than 25 years and hundreds of studies later, one of the originators of the five- factor model accurately described it as marking a turning point in the history of personality psychology (McCrae, 2011, p. 210).
Personality Measurement The factors were confirmed through a variety of assessment techniques including self- ratings, objective tests, and observers reports. McCrae and Costa then developed a personality test, the NEO Personality Inventory, using an acronym derived from the initials of the first three factors. Studies of twins have found that four of the five factors show a stronger hereditary component: neuroticism, extraversion, openness, and conscientiousness. Agreeableness was found to have a stronger environmental component. There is a similarity between the extraversion and neuroticism factors of McCrae and Costa and the extraversion and neuroticism dimensions proposed by Eysenck. Agreeableness and conscientiousness in the McCraeCosta model may represent the low end of Eysenck s psychoticism dimension (impulse control). Openness shows a high positive correlation with intelligence. Similarly, agreeableness correlates with Adler s concept of social interest.
Cultural and gender differences The five factors have been consistently observed in Eastern as well as Western cultures, a finding that also supports a genetic component. McCrae and Costa noted that the Big Five factors and their traits appear to represent a common human structure of personality that transcends cultural differences. These five factors and their traits have been found in more than 50 diverse nations including Britain, Germany, Portugal, the Czech Republic, Turkey, Israel, China, Korea, Japan, France, the Philippines, Russia, India, Denmark, Italy, Lebanon, Canada, and Romania, and among both native-born and Hispanic residents of the United States. It is important to note that those countries in which the five factors have been measured tend to be urban, literate, well-educated societies. No evidence of the five factors was found in an extensive study of a small, isolated, largely illiterate tribal group residing in a remote area of Bolivia.
Cultural and gender differences Although the same factors are common to virtually all urban cultures, major differences have been recognized in their relative importance and social desirability from one culture to another. For example, Australians consider extraversion and agreeableness to be more desirable to have than the other three factors. Japanese consider conscientiousness to be more important than all other factors. In other words, in Japanese society it is more important for a person to be conscientious than to be extraverted, agreeable, open, or even emotionally stable. In Hong Kong and in India, agreeableness was found to be the most important factor. In Singapore, emotional stability was more important, whereas in Venezuela, the primary characteristic to praise is extraversion. No single factor was found to be more significant than others in Chile, Finland, Germany, the Netherlands, Norway, Turkey, and the United States. Overall, Europeans and Americans tended to score higher in extraversion and openness to experience and lower in agreeableness than did Asians and Africans
Cultural and gender differences There seem to be consistent sex differences in the five factors. Research carried out in 55 countries, both Eastern and Western, found that women reported higher levels of neuroticism, extraversion, agreeableness, and conscientiousness than men. These differences were most pronounced in prosperous and egalitarian nations where women had greater opportunity for education and employment.
Is personality stable over-time? The five factors have been found in children as well as adults. Longitudinal research studying the same people over a 6-year period demonstrated a high level of stability for all five traits. Those high in agreeableness as children were likely to remain so as adults. A large-scale research review showed that neuroticism, extraversion, and openness appeared to decrease as people reached their 60s, whereas agreeableness and conscientiousness seem to increase with age (Debast et al., 2014).
