Eysenck's Theory of Personality: Biological Basis and Temperament Factors

1. Chapter 9The Biological Approach:Theory and Application

2. Eysenck’s Theory of Personality

3. Hans J. Eysenck (1916-1997) • Was born in Germany into a family of celebrities. • Against his family’s wishes, moved to France to pursue a career in physics and astronomy. • After a year, moved to England in 1934 to avoid having “to join the Nazi storm troops” and completed his Ph.D. in psychology at the University of London. • Published 79 books and over 1000 journal articles during his long career at the University of London. • Was a “controversialist in the intellectual world” (e.g., psychoanalysis, intelligence, smoking).

5. Eysenck’s “superfactors”

7. A biological basis for personality: extraversion/introversion • Eysenck argued that extraverts and introverts differ not only in their behavior but also, and more importantly, in their physiological makeup. • He originally maintained that they have different levels of cortical arousal while in a “baseline” resting state. According to Eysenck, extraverts have a lower level of cortical arousal than do introverts (Assumption 1). • He further maintained that extraverts act as if they are “stimulation hungry”—motivated to seek out stimulation that will raise their cortical arousal to an optimal level. In contrast, introverts act as if they are easily “overstimulated.” They are motivated to seek quiet and solitude to bring their cortical arousal back down to an optimal level (Assumption 2). • In general, the research findings support Eysenck’s second assumption but not his first assumption.

8. A biological basis for personality: neuroticism and psychoticism • Neuroticism is the second of Eysenck’s “superfactors” • Neurotic individuals are emotionally unstable; they have large and frequent mood swings and tend to be “worry warts” who obsess about problems large and small. • Non-neurotic individuals are emotionally stable; they don’t overreact to problems or other emotion-inducing events and they tend to act calmly and deliberately in response. • Psychoticism is the third of Eysenck’s “superfactors” • Psychotic individuals are characterized as egocentric, aggressive, impersonal, cold, lacking in empathy, impulsive, exploitative, and lacking in concern for others • Non-psychotic individuals are more altruistic, accommodating, warm, empathic, and considerate of others’ feelings and needs.

9. Sensitivity to outside stimulation and sensitivity to reward versus punishment • General sensitivity difference: • In general, introverts seem to be more sensitive and reactive to outside stimulation than extraverts are (that is, introverts are more readily “overstimulated”). • Selective sensitivity differences: • Extraverts are generally more sensitive and reactive to the reward potential of outside stimulation than introverts are. • Neurotic individuals are generally more sensitive and reactive to the punishment potential of outside stimulation than non-neurotic (emotionally stable) individuals are.

10. Eysenck’s three arguments for his claim that personality differences are based in biology • First, there is research evidence for cross-temporal consistency of individual differences in extraversion-introversion across the lifespan (test-retest correlations as high as the .70s over the span of decades). • Second, there is evidence that the “superfactors” of extraversion, neuroticism, and psychoticism have appeared as distinct factors in various cross-cultural studies and in studies using different methods of data collection. • Third, there is direct evidence for the heritability of extraversion and neuroticism in behavioral genetics studies using either the twins-study method or the adoptions-study method. • After examining these various sources of evidence, Eysenck (1982) estimated that as much as two-thirds of the variance in personality development can be traced to biological factors.

11. Temperament

12. Buss and Plomin’s proposed temperament factors • Emotionality • Activity • Sociability • Impulsivity (These factors should be EASI to remember.) Like Eysenck, Buss and Plomin assume that one’s temperament is largely inherited, and that the differences in children’s temperaments are evident very early in life.

14. Caspi’s (2000) longitudinal study of people born in Dunedin, New Zealand • Approximately 91% of the children born in this city between April 1, 1972 and March 31, 1973 were tested for temperament at age 3. • Three distinct temperament types were identified at this age: • The well-adjusted children exhibited self-control and self-confidence. • The undercontrolled children were impulsive, restless, and easily distracted. • The inhibited children were fearful, wary, and reluctant to get involved with others. • Over the course of the next 30 years, the researchers observed that: • The well-adjusted children became healthy, well-adjusted adults • The undercontrolled children had more problems with fighting, lying, and disobeying, and later experienced more legal, employment, and relationship problems. • The inhibited children fussed and worried more while growing up, and as adults were socially less engaged and more likely to report depression.

15. The processes through which temperament influences personality development are complex • Both temperament and life experiences influence personality development (e.g., emotionality and aggression). • The child’s temperament influences the way that both family members and other people react to and interact with the child (e.g., a timid, fearful child might be loved and protected within the family, but be able to make few, if any, friends outside the family). • The child’s temperament influences his or her environment in other ways as well (e.g., sociable children will actively build large social networks for themselves, whereas unsociable children will not.) • When the child’s temperament is misinterpreted by others, problems are likely to result (e.g., a hyperactive child may be seen as difficult and unwilling to learn by a new and inexperienced teacher). Personality = temperament modified by life experiences

16. Kagan and Moss’s (1962) study of inhibited and uninhibited children • Children’s traits were rated by observers at age 2-3 and again at 20. • About 10% of the children were classified as inhibited, displaying an anxiety to novelty. • These inhibited children tended to be more ectomorphic, more susceptible to allergies, and more likely to have blue eyes. • Children who display the signs of being inhibited early in life tend to be more wary and cautious later in life.

17. Correlations between earlier inhibition measures and behaviors at age 5½ years (Reznick et al., 1986)

18. Thomas and Chess’s nine temperament dimensions • Activity level • Rhythmicity • Approach or withdrawal • Adaptability • Threshold of responsiveness • Intensity of reaction • Quality of mood • Distractibility • Attention span and persistence

19. Application: Children’s temperaments and school (Thomas & Chess, 1997) • Research with Thomas and Chess’s nine temperament dimensions led to the identification of three basic behavior patterns in school-age children: • Easy children (about 40%) approach new situations, are adaptive, and generally experience a positive mood. • Difficult children (about 10%) tend to withdraw from new situations, are low in adaptability, and often experience intense negative moods. • Slow-to-warm-up children (about 15%), similar to the inhibited children described earlier, tend to withdraw from new situations and are slow to adapt to a new classroom task or activity. • Studies indicate that temperament is not related to intelligence • However, teachers’ failure to understand children’s temperaments can impair children’s progress in the classroom (e.g., the slow-to-warm-up child may be labeled unmotivated, and an easily distracted child may be seen as uninterested in learning). • The “Goodness of Fit” model has been proposed to help solve these problems.

20. Evolutionary Personality Psychology

21. Evolutionary personality psychology • Evolutionary personality theory proposes that many characteristics of “human nature” are psychological mechanisms that evolved in response to the pressures of natural selection. • Just as physical mechanisms such as blood clotting and calluses have evolved in response to specific threats to survival, so have psychological mechanisms such as anger, an innate fear of strangers (xenophobia), and the need to form attachments evolved in response to other specific threats to survival. • Anxiety has been proposed as another evolved psychological mechanism, but one whose adaptive value may not be so obvious. It may be very adaptive, however, in helping us to avoid the negative consequences of social exclusion. • Anxiety is associated with a range of cultural taboos, including those against adultery, within-group aggression, and within-group appropriation of others’ resources (theft).

22. Cerebral Asymmetry

23. Assessment: Brain electrical activity and cerebral asymmetry • Both Freud and Allport argued that the day would come when we could study personality differences at the physiological level. • One way in which that is currently being done is through the study of brain wave activity, as measured with the use of an instrument called the electroencephalograph (EEG). • Brain waves of different frequencies (cycles per second) have been identified, including alpha, beta, delta, and theta waves. • Alpha wave activity is commonly studied because it is relatively easy to isolate. Note that low alpha activity indicates greater overall activation in that area of the brain.

24. EEG recording

25. Assessment: Brain electrical activity and cerebral asymmetry • Both Freud and Allport argued that the day would come when we could study personality differences at the physiological level. • One way in which that is currently being done is through the study of brain wave activity, as measured with the use of an instrument called the electroencephalograph (EEG). • Brain waves of different frequencies (cycles per second) have been identified, including alpha, beta, delta, and theta waves. • Alpha wave activity is commonly studied because it is relatively easy to isolate. Note that low alpha activity indicates greater overall activation in that area of the brain.

27. Assessment: Brain electrical activity and cerebral asymmetry • Both Freud and Allport argued that the day would come when we could study personality differences at the physiological level. • One way in which that is currently being done is through the study of brain wave activity, as measured with the use of an instrument called the electroencephalograph (EEG). • Brain waves of different frequencies (cycles per second) have been identified, including alpha, beta, delta, and theta waves. • Alpha wave activity is commonly studied because it is relatively easy to isolate. Note that low alpha activity indicates greater overall activation in that area of the brain.

28. Cerebral asymmetry • Alpha wave activity often reveals different levels of activation in the left and right anterior (frontal) regions of the brain. Researchers refer to this difference as cerebral asymmetry. • Higher activation in the right hemisphere is associated with negative moods, whereas higher activation in the left hemisphere is associated with positive moods. • When people experience feelings of disgust, as evidenced by their facial expressions, there is more activation in the right cerebral hemisphere. When they experience feelings of happiness, there is more activation in the left cerebral hemisphere. • > right hemisphere activation = negative mood • > left hemisphere activation = positive mood

30. Cerebral asymmetry: Adifference we are born with • Much of the work on cerebral asymmetry has been conducted by Richard Davidson and his colleagues. • The effects of cerebral asymmetry have been demonstrated in 10-month-old infants. Smiling in these infants was associated with greater left hemisphere activity, whereas crying was associated with greater right hemisphere activity. • Infants have also been shown to have greater left hemisphere activity when their mothers reached down to pick them up, when they heard laughter, and when they tasted something sweet. • These and other findings indicate that the association between cerebral asymmetry and emotion is something we are born with rather than the result of learning.

31. Individual differences in cerebral asymmetry • People differ in the type and amount of cerebral asymmetry they display during a resting state. • These individual differences in cerebral asymmetry tend to be relatively stable over time. • For that reason, EEG data can be used to predict which people are more likely to experience certain kinds of moods or mood disturbances. • For example, people with higher relative levels of left hemisphere activity report feeling more positive emotion in response to positive mood films, whereas people with higher relative levels of right hemisphere activity report feeling more negative emotion in response to negative mood films.

32. Individual differences in cerebral asymmetry • Similarly, when babies are divided into those who either do or don’t cry when separated from their mothers, the criers tend to display more right hemisphere activity than the noncriers when their EEG activity is assessed. • Davidson has argued that cerebral asymmetry affects people’s thresholds for responding to stimuli that have the potential to evoke positive or negative moods. • In contrast, Harmon-Jones has argued that left hemisphere activity is associated with movement toward the source of the emotion (approach behavior), whereas right hemisphere activity is associated with movement away from the source of the emotion (avoidance behavior). Consistent with this argument, anger has been related to greater left hemisphere activity. • Depressed individuals show more right-side activation than nondepressed individuals, and the same finding holds even for people who have been successfully treated for depression.

33. Strengths and criticisms of the biological approach • Strengths • It provides a bridge between the fields of psychology and biology. • It both asserts and demonstrates that our genetic makeup plays an important role in determining our personality. • It identifies some realistic parameters for psychologists who are interested in behavior change. • It has generated a great deal of research. • Criticisms • Evolutionary personality psychologists must often argue from the relatively weak position of analogy and reasonable deduction. • There is no agreed-upon model of temperament. • The biological approach offers few suggestions for personality change.