PEN Model

Table of Contents Biological Dimensions Descriptive Causal Extraversion Neuroticism Psychoticism Theorists Table References Links Home

The PEN model is comprised of three personality dimensions based on psychophysiology: Psychoticism, Extraversion, and Neuroticism. As dimensions of temperament, the three dimensions are related to Basic Emotions. A competing model of personality structure is the Five-Factor Model. 
 

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Biological Dimensions of Personality

Descriptive Aspects

The PEN model, proposed and advocated by Eysenck as the overarching paradigm of personality psychology, has two main aspects: descriptive and causal. The descriptive aspect of the model is a hierarchical taxonomy based on factor analysis. At the top of the hierarchy are the superfactors of Psychoticism, Extraversion, and Neuroticism (PEN). These superfactors are comprised of factor analyses of lower-order factors such as sociability and positive affect (components of Extraversion). These factors are comprised of factor analyses of low-order habits such as liking to study with a group of people (a component of sociability). These habits are comprised of factor analyses of lower-order behaviors such as studying for the personality midterm with a group of people.Two important principles of personality research that are incorporated into the PEN model are aggregation and the state-trait distinction. The principle of aggregation is that measures will have higher reliability if they are comprised of many items. For example, Extraversion is comprised of many different factors, habits, and behaviors, and therefore should have good reliability. The state-trait distinction is also built into the PEN model. At the top level, the superfactors of P, E, and N are traits that are very stable across time and situation. At the bottom level, the behavior of studying for the midterm with a group of people is a state that could vary widely, for example, with the availability of study partners. While states are very changeable, traits are very stable.Eysenck believes that the five-factor model is a hodge-podge of factors and superfactors. The five-factor model and the PEN model both include Extraversion and Neuroticism at the highest level. However, the superfactor of Psychoticism is made up of the lower-level factors of (dis-) agreeableness and (non-) conscientiousness. Moreover, the big five include "intellect" (self- or peer rated) at the top level. Eysenck thinks of this as simply a bad way of measuring intelligence, which is a cognitive ability that would be better reflected in I.Q. tests than in self-reports on adjective questionnaires.
One factor that was originally subsumed under the superfactor of Extraversion in the Eysenck Personality Inventory (EPI) is impulsivity. Later, when the dimension of Psychoticism was added, impulsivity was moved from Extraversion to Psychoticism in the Eysenck Personality Questionnaire (EPQ). Some investigators, such as Gray and Revelle, believe impulsivity is uniquely important, and that its removal from the Extraversion superfactor is a bad idea.

Causal Aspects

Extraversion. The PEN model is biologically based. 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. The finding that arousal is related to performance as an inverted U-shaped curve is called the Yerkes-Dodson Law.Extraversion is related to social interest and positive affect. Some investigators have proposed that social interest causes positive affect, since the best of times are usually those spent with other people. However, Diener and Larsen (1993) have found that this hypothesis is incorrect. Another alternative is that positive affect causes social interest, since being very enthusiastic and fun loving may make people want to go out and be with other people. This hypothesis has not yet been studied. Yet another possibility is that a third factor causes both positive affect and social interest. Dopamine responsivity, which makes people highly sensitive to reward, may be the factor responsible for both positive affect and social interest.Neuroticism. Neuroticism is based on activation thresholds in the sympathetic nervous system or visceral brain. This is the part of the brain that is responsible for the fight-or-flight response in the face of danger. 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.
It is interesting to note that measures of activation are not highly correlated. That is, people differ in which responses are influenced by stress--some sweat, others get headaches. This is called individual response specificity. It is also interesting to note that stressors differ in the responses they elicit. This is called stimulus response specificity.
Psychoticism. Psychoticism is associated not only with the liability to have a psychotic episode (or break with reality), but also with aggression. While less research has been done on Psychoticism than on Extraversion and Neuroticism, the research that has been done has indicated that Psychoticism too has a biological basis: increased testosterone levels.
In order to draw causal conclusions, researchers on the PEN model have not been content to use only correlational research methods such as factor analysis, but have gone further and used experimental research methods. These methods have been used not only on humans, but also on non-human animals such as rats. (Isn't it interesting that Eysenck believes even rats have personality--with the same three dimensions as humans?!)

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Theorists Table

	Extraversion	Neuroticism	Psychoticism
Atkinson 1	Approach Motivation / Need for Achievement / Joy of Success	Avoidance Motivation / Fear of Failure / Pain of Failure
Barratt	Action Orientation	Anxiety
Cloninger	Behavioral Activation / Novelty Seeking	Behavioral Inhibition / Harm Avoidance	Behavioral Maintenance / Reward Dependence
Davidson	Approach / (Non-) Depression	Avoidance / Inhibition / Depression
Depue	Behavioral Facilitation / Mania / Positive Emotionality	Behavioral Inhibition
Dollard and Miller 2	Approach	Avoidance
Eysenck	Extraversion / Arousal / Positive Affect	Neuroticism / Activation / Negative Affect	Psychoticism / Anger
Fowles	Behavioral Activation / Impulsivity / Positive Affect	Behavioral Inhibition / Aversion	Non-Specific Arousal
Gray	Behavioral Approach / Impulsivity / Positive Affect	Behavioral Inhibition / Anxiety / Negative Affect	Fight vs. Flight / Aggression
Kagan		Behavioral Inhibition
Newman	Impulsivity / Positive Affect	Anxiety / Negative Affect
Revelle	Approach / Instigation of Behavior	Avoidance / Inhibition of Behavior	Aggression
Simonov	"Strong" Type (Choleric) vs. "Weak" Type (Melancholic)
Tellegen	Positive Affectivity / Positive Affect	Negative Affectivity / Negative Affect	Constraint Avoidance
Thayer	Energetic Arousal	Tense Arousal
Watson and Clark	Positive Affectivity	Negative Affectivity
Zuckerman	Extraversion / Positive Affect	Neuroticism	Psychoticism / Impulsivity / Sensation Seeking / Aggression-Anger
	Extraversion	Neuroticism	Psychoticism

(This table is adapted from Revelle [1997], and Eysenck [1990].)

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References

Eysenck, H. J. (1990). Biological dimensions of personality. In L. A. Pervin (Ed.), Handbook of personality: Theory and research (pp. 244-276). New York: Guilford.Revelle, W. (1997, August 12). Three fundamental dimensions of personality [WWW document]. URL http://personality-project.org/perproj/theory/big3.table.html

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PEN Model Links

PEN Model: Student Papers in This Website

"Creative Genius of Psychotic? A Look at the Strong Positive Correlation Between Creativity and Psychoses"
This paper shows how intelligence, latent inhibition, and fantasy proneness all factor into a theory of how creativity and psychoses are intertwined. By Jonathan S. Byrd.
"A Critical Review of Eysenck's Theory of Psychoticism and How It Relates to Creativity"
This paper describes Eysenck's contribution to the notion that the personality trait of psychoticism is related to creativity, along with criticisms of this notion. By Shane K. Porzio.
"Factors Contributing to the Development of Pathological Gambling"
This paper points out relations between impulsivity and other risk factors for developing gambling problems. By Kory Sinha.
"Eysenck's PEN Model: Its Contribution to Personality Psychology"
This paper summarizes and evaluates the Psychoticism - Extraversion - Neuroticism (PEN) model and its reformulation by Gray, concluding that the PEN model has made an important contribution by uniting correlational study of personality taxonomy with experimental study of the causes of personality. By KwangMin Jang.

PEN Model: Papers Elsewhere

"Hans Eysenck"
This paper is an introduction to Eysenck's theories. By C. George Boeree.
"Measurement of Impulsivity in a Hierarchical Model of Personality Traits: Implications for Substance Use"
This paper reviews the literature on impulsivity as a risk factor for substance use. By G. Scott Acton.
"Personality Processes"
This paper is a scholarly survey of the field of personality psychology--including the behavioral activation system (BAS) and behavioral inhibition system (BIS)--in the 1995 Annual Review of Psychology. By William Revelle.
"Three Fundamental Dimensions of Personality"
This introduction to the PEN model is part of the Personality Project. By William Revelle.

PEN Model: Websites Elsewhere

The H. J. Eysenck Official Home Page
This official home page of the late Hans Eysenck is maintained by his son. By Darrin Evans.
The Psychology of Risk-Taking Behavior
This is an introduction to a scientific explanation of why people take risks with their health and engage in high-risk sports. By David J. Llewellyn.

PEN Model: Reference Sources

Suggested Readings
A list of suggested readings on this topic is also available. By G. Scott Acton.

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Last modified January 1999
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