Lecture 3

1. Lecture 3 Trait Theories II Dr. K. V. Petrides www.psychometriclab.com KV Petrides KV Petrides

2. KV Petrides Trait theories of personality • The trait approach to personality is undoubtedly the dominant approach in the field. Some major advantages of trait theories: • Predicated on a vast body of empirical evidence. • Explicit, testable, and subject to falsification. • Results and observations are replicable. • While there is little doubt as regards the relative advantages of the trait approach, the question of whose trait theory is best has led to ferocious battles between some of the greatest psychologists of all time.

3. KV Petrides “Raymond Cattell has been one of the most influential and original psychologists working in the field of individual differences in intelligence and personality, in psychometrics and in behaviour genetics, and his voluminous writings have been crucial in the development of a scientific psychology.  Many of his discoveries have become universal property, such as the distinction between fluid and crystallized ability, or the state-trait dichotomy.  Few people can have a better claim for recognition by virtue of the rigor and originality of the work done.” - Hans J Eysenck (written shortly before their death) “When he died, he was the most cited living psychologist and he is the third most cited psychologist of all time (after Sigmund Freud and Jean Piaget). In this writer’s opinion, Hans Eysenck was the single most important psychologist who ever lived. His citation legacy will be tracked for decades to come.” – J Philippe Rushton (2001, Personality and Individual Differences, 31, 17-39).

4. KV Petrides Eysenck’s theory of personality I • To summarize 1000+ journal articles and 80 books: • Eysenckian theory developed considerably after Eysenck’s (1947) seminal book Dimensions of Personality. • His initial theory proposed two basic personality dimensions, viz., Extraversion versus Introversion and Neuroticism versus Stability. • Extraversion is characterized by adjectives like ‘sociable’ and ‘active,’ whereas the opposite pole (introversion) is characterized by adjectives like ‘quiet’ and ‘passive’. • Neuroticism is characterized by adjectives like ‘moody’ and ‘touchy,’ whereas the opposite pole (stability) is characterized by adjectives like ‘calm’ and ‘relaxed’.

5. KV Petrides UNSTABLE Moody Touchy Anxious Restless Rigid Aggressive Sober Excitable Pessimistic Changeable Reserved Impulsive Unsociable Optimistic Quiet Active Melancholic Choleric INTROVERTED EXTROVERTED Passive Sociable Careful Outgoing Thoughtful Talkative Peaceful Responsive Controlled Easygoing Reliable Lively Even-tempered Carefree Calm Leadership Phlegmatic Sanguine STABLE

6. KV Petrides Eysenck’s theory of personality II • Eysenck (1976) added a third major dimension to the taxonomy, viz., Psychoticism versus Normality. This was the second psychopathological dimension in the system, incorporated because the two existing dimensions could not distinguish between borderline schizophrenics and controls. • Psychoticism is characterized by adjectives like ‘emotionally cold’ and ‘nonconformist,’ whereas the opposite pole (normality) is characterized by adjectives like ‘warm’ and ‘empathic’. • There is considerable empirical evidence underpinning the Eysenckian factors (especially E and N).

7. KV Petrides

8. KV Petrides Introversion versus Extraversion - Theory • Eysenck hypothesized that the biological basis of Extraversion lies in individual differences in cortical arousal. • Introverts tend to have a chronically over-aroused central nervous system (CNS; brain and spinal cord), whereas extraverts tend to have a chronically under-aroused CNS. • Introverts are less susceptible to reactive inhibition (Hull’s concept of neural fatigue building from repeated exposure to the same stimulus or action).

9. KV Petrides Introversion versus Extraversion - Evidence • Introverts versus Extraverts: • Over- versus under-responsive central nervous system • Evidence: introverts less likely to use alcohol, cigarettes, drugs. • Strong versus weak excitatory processes. • Evidence: Introverts have lower pain tolerance. • More versus less cortical arousal. • Evidence: Introverts better able to tolerate sensory deprivation. • Brains react more versus less quickly and strongly (brain reactivity hypothesis). • Evidence: Introverts are easier to condition (but not always). • Less versus more susceptible to reactive inhibition. • Evidence: Introverts tend to persist at activities longer.

10. KV Petrides Neuroticism versus Stability • Eysenck hypothesized that the biological basis of Neuroticism lies in individual differences in the lability of the autonomic nervous system (ANS). • The ANS is part of the peripheral nervous system and consists mainly of sensory and motor neurons. It is responsible for monitoring conditions in the internal environment and bringing about appropriate changes in them. • Neurotics tend to have a more labile (unstable, readily open to change, rapidly adjustable) ANS than their stable peers. • While the theoretical predictions are relatively clear and specific, corroborating evidence from psychophysiological studies of N has not been forthcoming.

11. KV Petrides E and N as emotionality • As noted in Lecture 2, E and N have also been conceptualized as positive and negative emotionality respectively. E N Canli et al., 2001

12. KV Petrides Psychoticism versus normality • In many ways (e.g., theoretical, psychometric, empirical), Psychoticism is the weakest of the Eysenckian dimensions. • Eysenck did not develop a clear theory about the biological basis of Psychoticism. • There is robust evidence linking Psychoticism to maleness: • Males score higher than females on P scales. • Criminals and schizophrenics score higher on P and are overwhelmingly male. • Based on such evidence, Eysenck postulated that Psychoticism is linked to male hormonal levels (androgens).

13. KV Petrides Eysenck’s personality measures • The development of the inventories used to operationalize the Eysenckian dimensions has mirrored the development of the underlying theory.

14. KV Petrides Eysenck’s theory of personality III • Psychometric properties • Excellent factor structure. • Good reliabilities (P somewhat problematic). • Heritability indices • High heritability indices confer psychological significance on variables, thus countering objections that they might be statistical artifacts. • Eaves, Martin, and Eysenck (1989) suggested that up to about 70% of the population variance is attributed to genetic factors. The work of R Plomin is especially relevant and important here. • Physiological evidence • There has been moderate success with E and, less so, with N (see, e.g., Canli et al., 2001; Matthews & Gilliland, 1999). Eysenckian P remains under-researched. J A Gray’s theory a powerful competitor here. R Plomin

15. KV Petrides E’s theory – Cross-cultural data I • Barrett, Petrides, Eysenck, and Eysenck (1998) conclusively demonstrated the replicability of the three Eysenckian superfactors with data from 34 different countries. • High congruences for the Giant 3 as well as for the L(ie) scale. • More variable congruences for P and L than for E and N. • Results demonstrate that even though specific items may be lost across cultures (especially in the case of P), the core factors remain identifiable and mathematically discriminable.

16. Barrett et al. (1998) KV Petrides E’s theory – Cross-cultural data II Male data Female data

17. KV Petrides E’s theory – External correlates • Below are some ‘real-life’ criteria that have been found to correlate reliably with the Eysenckian dimensions: • Extraversion • Sporting behaviour, early onset of sexual behaviour, tobacco and alcohol consumption, hedonism, accident proneness. • Neuroticism • Unsatisfactory sex life, stress symptoms, cancer (-), gaze aversion, likelihood of divorce (mainly in females). • Psychoticism • Instrumental aggression (e.g., robbery, burglary), car theft, pornography consumption, permissive attitudes towards sex.

18. KV Petrides Gray’s theory of personality I • Jeffrey Gray proposed a modification of Eysenck’s model leading to a theory that is more firmly rooted in psychophysiological mechanisms. • Gray postulated that the brain has separate reward and punishment systems, which are important in the development of personality. • This hypothesis was originally predicated on animal learning and physiological research. • Most empirical support for this theory has been obtained through animal research.

19. KV Petrides Gray’s theory of personality II • Gray proposed a 45° (later amended to 30°) rotation of the Eysenckian dimensions of Extraversion and Neuroticism. • This rotation resulted in two alternative dimensions to describe the same factor space. • Anxiety, which concerns individual differences in sensitivity to punishment. This dimension runs from stable extraversion, at the low end, to neurotic introversion, at the high end. • Impulsivity, which concerns individual differences in sensitivity to reward. This dimension runs from stable introversion, at the low end, to neurotic extraversion, at the high end.

20. KV Petrides Gray’s theory of personality III

21. KV Petrides BAS/BIS I • Anxiety and impulsivity are associated with the two brain systems that control sensitivity to reward (BAS) and punishment (BIS), respectively. • The Behavioural Activation System (BAS) is related to sensitivity and motivation to seek potential rewards (e.g., sexual drive). It is also known as the ‘GO’ system. • The Behavioural Inhibition System (BIS) is related to sensitivity and motivation to avoid punishment (e.g., aggression). It is also known as the ‘avoidance motivation’ or ‘STOP’ system.

22. KV Petrides BAS/BIS II • Correlates and characteristics of BAS: • reward-seeking • experiencing positive emotions and anticipating good events • impulsivity • depression (under-sensitive BAS) • Correlates and characteristics of BIS: • responsive to cues of punishment or danger • inhibits movement towards goals • anxiety • depression

23. KV Petrides BAS/BIS, arousal, and E & N • BAS and BIS are mutually inhibitory. • Both BAS (produces energy) and BIS (produces tension) influence the arousal system. • Extraversion relates primarily to BAS (30°). • Neuroticism relates primarily to BIS (30°).

24. KV Petrides Gray’s theory - Evidence • Support for Gray’s theory has been scarce and inconsistent. • There is impressive evidence from animal studies supporting BIS-based explanations of the effects of anxiolytic drugs. • However, these results do not seem to be replicable in human samples. It is likely that human anxiety is much more amenable to cognitive control (self-regulatory processes) than animal anxiety. • The psychometrics of the theory are problematic both in terms of the operationalization of the BIS/BAS and in terms of their interrelationship. • If BIS/BAS are mutually inhibitory, is it sensible to think of anxiety and impulsivity as orthogonal?

25. KV Petrides On the web • http://www.personality-project.org/ • Maintained by W. Revelle • http://freespace.virgin.net/darrin.evans/ • The H J Eysenck official web page • http://www.cattell.net/devon/rbcmain.htm • The R B Cattell memorial page • http://www.spsp.org/ • Society for Personality and Social Psychology