HANS EYSENCK(TM)S THEORY OF PERSONALITY

Eysenck hypothesized that some people have a more responsive sympathetic nervous system than others. Some people remain very calm during emergencies; some people feel considerable fear or other emotions; and some are terrified by even very minor incidents.  He suggested that this latter group had a problem of sympathetic hyperactivity, which made them prime candidates for the various neurotic disorders. (Dr. Boeree, 1998)
A panic attack is also an offshoot of this personality dimension. Most people suffer from these attacks, albeit in varying degrees. Most people feel apprehension at crossing a rickety bridge and this is quite normal. This can be carried to a point where a person is more afraid of being afraid that of actually crossing the bridge. This could consequently be labeled as neurotic (Sandra Jones, 2007).

So physiologically, neuroticism is based on activation thresholds in the sympathetic nervous system or visceral brain. Activation can be measured by heart rate, blood pressure, cold hands, sweating, and muscular tension (especially in the forehead). Neurotic people, who have a low activation threshold, experience negative affect (fight-or-flight) in the face of very minor stressors--i.e., they are easily upset. Emotionally stable people, who have a high activation threshold, experience negative affect only in the face of very major stressors--i.e., they are calm under pressure (PEN Model, 1999).

2. EXTRAVERSION-INTROVERSION 

The second dimension of his theory is extraversion-introversion; shy, quiet people versus out-going, even loud people. Eysenck hypothesized that extraversion-introversion is a matter of the balance of inhibition and excitation in the brain itself.  Someone who is extraverted, he hypothesized, has good, strong inhibition (Dr. Boeree, 1998). Dr. C. George Boeree, in his 1998 article titled 'Hans Eysenck and other Temperament Theorists', summarized Eysenck's hypothesis of excitation and inhibition by the following:

"An extrovert is someone who, when faced with a trauma, such as a car crash is 'numbed' to the experience. He remembers little of the circumstances of the accident and needs details to be supplied to him. As he remembers nothing, he continues to be unaffected and learns very little from his mistakes. An introvert, however, would remember everything about the crash in minute detail and is unlikely to carry on the activity as normal - he learns from his mistakes."
        Boeree also noted that Eysenck discussed the idea that violent criminals tend to be 'non-neurotic' extroverts. This would support the theory that habitual criminals continually repeat their crimes, mistakes and all. Introverts would be seemingly hard pressed to follow in such a manner; however, there are many areas of criminal activity in which they may excel (Sandra Jones, 2007).

So extraversion is based on cortical arousal. Arousal can be measured by skin conductance, brain waves, or sweating. While theoretically introverts are chronically overaroused and jittery, theoretically extraverts are chronically underaroused and bored. The theory presupposes that there is an optimal level of arousal, and that performance deteriorates as one becomes more or less aroused than this optimal level (PEN Model, 1999).

NEUROTICISM AND EXTRAVERSION-INTROVERSION

Another thing Eysenck looked into was the interaction of the two dimensions and what that might mean in regard to various psychological problems.  He found, for example, that people with phobias and obsessive-compulsive disorder tended to be quite introverted, whereas people with conversion disorders (e.g. hysterical paralysis) or dissociative disorders (e.g. amnesia) tended to be more extraverted. His explanation is that highly neuroticistic people over-respond to fearful stimuli. If they are introverts, they will learn to avoid the situations that cause panic very quickly and very thoroughly, even to the point of becoming panicky at small symbols of those situations -- they will develop phobias. Other introverts will learn (quickly and thoroughly) particular behaviors that hold off their panic -- such as checking things many times over or washing their hands again and again.

Highly neuroticistic extraverts, on the other hand, are good at ignoring and forgetting the things that overwhelm them.  They engage in the classic defense mechanisms, such as denial and repression of emotions or problems. They can conveniently forget a painful weekend, for example, or even “forget” their ability to feel and use their legs (Dr. Boeree, 1998).

3. PYSCHOTICISM

At a latter stage in his research from his studies of mentally disturbed people, Eysenck added a third dimension of psychoticism. It can be related to risk-taking and eccentricity (Alan Chapman, 2005).  This grouping of people seems to encompass what is commonly termed 'social misfit'. These people are often found to be cruel, insensitive and have no care for other people's feelings or existence (Sandra, 2007). His description of psychoticism states that a person will exhibit some qualities commonly found among psychotics, and that they may be more susceptible, given certain environments, to becoming psychotic. Examples of such psychotic tendencies include recklessness, disregard for common sense, and inappropriate emotional expression to name a few (Porzio, 2003).Psychoticism is associated not only with the liability to have a psychotic episode (or break with reality), but also with aggression (PEN Model, 1999).

REFERENCES:

1. Dr. C. George Boeree, (1998) Hans Eysenck And Other Temperament Theorists Retrieved 21st April, 2009 from the website http://webspace.ship.edu/cgboer/eysenck.html
2. Sandra Jones (2007) , Eysenck's Theory of Personality Retrieved 21st April, 2009 from the website http://www.associatedcontent.com/article/111431/eysencks_theory_ of_personality.html 
3. PEN Model, 1999 Retrieved 21st April, 2009 from the website http://www.personalityresearch.org/pen.html
4. Alan Chapman, (2005) Eysenck’s Personality Inventory And The Four Temperaments Retrieved 21st April, 2009 from the website http://www.businessballs.com/ personalitystylesmodels.htm
5. Shane K. Porzio, (2003) A Critical Review of Eysenck's Theory of Psychoticism and How it Relates to Creativity Retrieved 21st April, 2009 from the website http://www.personalityresearch.org/papers/porzio.html
6. Hans Eysenck,  (n.d) Retrieved 21st April, 2009 from the website http://www.absoluteastronomy.com/topics/Hans_Eysenck
7. Figure from http://www.a2zpsychology.com/a2z%20guide/mpi.htm