Contribution of Eysenck\'s PEN Model PDF

Preview

Summary

PEN MODEL...

Description

11/28/2018

Contribution of Eysenck's PEN Model

Home

SAPA Project Test

Papers

Eysenck's PEN Model: Its Contribution to Personality Psychology KwangMin Jang Northwestern University To explain individual differences in personality or temperament, Eysenck proposed the PEN model and Gray attempted to reformulate Eysenck's theory. This paper summarizes and evaluates the PEN model. Special attention is given to the contribution of the PEN model to an experimental approach to the study of personality. In the PEN model, personality is comprised of three major dimensions: extraversion, neuroticism, and psychoticism. These descriptive dimensions have psychophysiological roots in which cortical arousal causes extraversion, visceral brain activation causes neuroticism, and gonadal hormones and enzymes cause psychoticism. In the search for a model of individual differences in personality, many theorists have suggested criteria for a good model. Among the criteria suggested are evidence of "temporal stability and cross-observer validity" (Costa & McCrae, 1992a, p. 653), universality, testability, replicability, and practicality (Eysenck, 1991; Gray, 1981). In particular, Eysenck (1990) distinctively suggests that an adequate model of personality must have two interlocking aspects: descriptive or taxonomic, and causal or biological. From this perspective, Eysenck (1991) further claims that the PEN model constitutes a paradigm in personality research. To support the theory, proponents of the PEN model (e.g., Eysenck & Eysenck, 1985) emphasize the use of not only correlational research methods such as factor analysis, but also experimental research methods. In the course of the research, some theorists (e.g., Gray, 1981; Revelle, Humphreys, Simon, & Gilliland, 1980; Zinbarg & Revelle, 1989) have attempted to modify Eysenck's original theory to better account for their empirical data. Nevertheless, the PEN model deserves a good evaluation for its contribution to the development of personality psychology. Distinctively, the PEN model strongly advocates the scientific process for evaluating theories with experimental evidence. This paper will summarize and evaluate the PEN model, focusing especially on Eysenck's theory of individual differences in human temperament and Gray's reformulation of Eysenck's theory.

Descriptive Aspects Hierarchical Taxonomy Personality can be studied from either temperamental or cognitive aspects, or both (Eysenck & Eysenck, 1985). Eysenck (1991), however, focuses on the temperament aspect of personality in his PEN model. For better understanding of the PEN model, therefore, the study should begin with its description or taxonomy of personality or temperament. As Eysenck (1991) states, "In any science, taxonomy precedes causal analysis" (p. 774). In the course of taxonomy, any organisms can be organized into groups based on characters and their relationships. Eysenck describes in plain terms http://www.personalityresearch.org/papers/jang.html

1/15

11/28/2018

Contribution of Eysenck's PEN Model

how taxonomy in the study of personality can be achieved using the correlational technique called factor analysis: In the case of personality study the organisms concerned are human beings, preferably randomly chosen, or with sex, age and other restrictions; the characters are traits, measured by experiment, by rating, by self-rating, or in some other way (e.g. projective test, miniature situations, etc.). We can correlate traits over subjects, or subjects over traits, giving us groups of people showing similarity over traits, or groups of traits, cohering as factors over people. We can then look at the traits (or people) having the highest factor loadings in order to better identify the trait clusters. (Eysenck, 1991, p. 775) Descriptively, individual differences in personality or temperament are analyzed in terms of traits, which can be defined as theoretical constructs based on "covariation of a number of behavioral acts" (Eysenck & Eysenck, 1985, p. 12). However, Eysenck (1991) further supposes that traits themselves intercorrelate and make up higher-order factors or superfactors, which Eysenck calls "types." As a result, the PEN model proposes a hierarchical taxonomy of personality containing four levels (Eysenck, 1990). At the very bottom level of the hierarchy are behaviors such as talking with a friend on a single occasion. At the second level are habits such as talking with friends on multiple occasions, which are comprised of recurring behaviors. The third level of the hierarchy is that of traits or factors such as sociability, which are comprised of intercorrelated sets of habits. At the top of the hierarchy are superfactors or dimensions of personality such as extraversion, which are intercorrelated sets of traits or factors. Eysenck suggests three such superfactors: extraversion (E), neuroticism (N), and psychoticism (P). These three superfactors or dimensions of personality are orthogonal to each other, which means that they do not correlate with each other (Eysenck & Eysenck, 1985). The PEN model is based on the principle of "aggregation," in which measures will have higher reliability if they are comprised of many items (Eysenck, 1990). That is, each superfactor in the PEN model is comprised of many different factors, habits, and behaviors, and thus reliability of measurement is increased. The PEN model is also based on the state-trait distinction. Traits are "semipermanent personality dispositions," whereas states are "transient internal conditions" that are produced when traits and situations interact with each other (Eysenck & Eysenck, 1985, p. 33). That is, the superfactors of extraversion, neuroticism, and psychoticism at the top level of the hierarchy are stable, whereas behaviors such as talking with a friend on a single occasion at the bottom of the hierarchy are changeable across time and situation. In this respect, the distinction between levels is very important for the analysis of personality in the PEN model.

Three Dimensions of Personality There are vigorous debates regarding the number of dimensions that define personality (Costa & McCrae, 1992a, 1992b; Eysenck, 1991, 1992b, 1992c). In this respect, Eysenck strongly advocates that there are only three major dimensions or superfactors in the description of personality: extraversion-introversion; emotional stability versus instability, or neuroticism; and psychoticism versus impulse control (Eysenck & Eysenck, 1985). In the PEN model, these dimensions or superfactors are based on "constitutional, genetic, or inborn factors, which are to be discovered in the physiological, neurological, and biochemical structure of the individual" (Eysenck & Eysenck, 1985, pp. 42-43). Researchers on the PEN model emphasize the dimensional aspect of personality, as opposed categorization (Eysenck, 1992a; Eysenck & Eysenck, 1985). That is, each person does not necessarily have either 100 percent or zero percent of extraversion, neuroticism, or psychoticism. An individual may show some degree of these superfactors on the continuum. A person may have http://www.personalityresearch.org/papers/jang.html

2/15

11/28/2018

Contribution of Eysenck's PEN Model

high extraversion, moderate neuroticism, and low psychoticism. Eysenck (1992a), for example, provides empirical evidence to support this "dimensional or continutiy hypothesis" for psychoticism (p. 776). Following are three interesting points Eysenck (1992a) suggests after studying psychosis: 1. Psychotic symptoms and illnesses do not form completely separate diagnostic entities, unrelated to each other, but are genetically related and form a general cluster with severity of illness the major distinguishing marker.... 2. Psychosis is not a separate diagnostic entity which is categorically separated from normality; it is merely an extreme along a continuum of abnormality shading into schizoid personality, 'spectrum' disorders, psychopathy and personality disorder, criminality and alcoholism, and average types of behaviour right to the other extreme of empathy, altruism and selflessness. 3. This continuum is co-linear with the concept of psychoticism, embodied (however imperfectly) in the P scale of the EPQ, and also in a number of 'schizotypy' constructs and scales.... All the elements of this theory are empirically testable, and have been so tested on numerous occasions. (pp. 776-777) On this continuum, a person with high extraversion is sociable, popular, optimistic, and rather unreliable, whereas a person with low extraversion is quiet, introspective, reserved, and reliable. A person with high neuroticism is anxious, worried, moody, and unstable, whereas a person with low neuroticism is calm, even-tempered, carefree, and emotionally stable. A person with high psychoticism is troublesome, uncooperative, hostile, and socially withdrawn, whereas a person with low psychoticism is altruistic, socialized, empathic, and conventional (Eysenck & Eysenck, 1985). Furthermore, the superfactors of extraversion, neuroticism, and psychoticism appear to be universal. Such universality has been demonstrated in cross-cultural studies using the Eysenck Personality Questionnaire (EPQ). Evidently, the studies show that the same dimensions of personality emerge in many different nations and cultures other than Western countries (Eysenck, 1991; Eysenck & Eysenck, 1985). Although the overall evidence supports the PEN model quite well, there are also many anomalies to be cleared up. For example, the trait of impulsivity was originally under the superfactor of extraversion in the Eysenck Personality Inventory (EPI), but later it was moved to psychoticism in the Eysenck Personality Questionnaire (EPQ) (Eysenck & Eysenck, 1985). What happened was that impulsivity correlated quite well with extraversion, "but even better with psychoticism" (Eysenck & Eysenck, 1985, p. 69). Some researchers, such as Gray (1981), disagree with this removal from extraversion and strongly believe that impulsivity, as well as anxiety, should be treated as uniquely important.

Causal Aspects Based on a three-dimensional description of personality, the PEN model further attempts to provide causal explanation of personality. The PEN model looks for psychophysiological, hormonal, and other biological mechanisms responsible for the personality dimensions, so that the theory can be tested by scientific experiments. Eysenck and Eysenck (1985) clearly contend that "no theory would be considered valid that did not make testable and verified predictions" (p. 187). Consequently, Eysenck (1990) proposes the arousal theory, by modifying his inhibition theory to explain the causal roots of the three dimensions of personality.

Extraversion and Cortical Arousal According to the arousal theory, Eysenck (1990) provides a biological explanation of extraversion in terms of cortical arousal via the ascending reticular activating system (ARAS). Activity in the ARAS stimulates the cerebral cortex, which, in turn, leads to higher cortical arousal. Cortical http://www.personalityresearch.org/papers/jang.html

3/15

11/28/2018

Contribution of Eysenck's PEN Model

arousal can be measured by skin conductance, brain waves, or sweating (Eysenck, 1990). Because of the different levels of ARAS activity, "introverts are characterized by higher levels of activity than extraverts and so are chronically more cortically aroused than extraverts" (Eysenck & Eysenck, 1985, p. 197, emphasis added). Based on the Yerkes-Dodson law, the arousal theory of the PEN model assumes that "some intermediate level of arousal is optimal for performance" (Eysenck & Eysenck, 1985, p. 199). The Yerkes-Dodson law suggests that arousal and performance have an inverted-U relationship. That is, task performance is impaired when motivation is either very low or very high, and performance is maximized at some intermediate level of "optimal" motivation. Geen (1984) also supports Eysenck's arousal theory. In his experiments, Geen measures preferred stimulation levels in introverts and extraverts and effects on arousal and performance. The results show that introverts choose a lower level of noise than do the extraverts, and both introverts and extraverts show no difference in arousal and performance with preferred noise level. Geen therefore concludes that "the best performance for both introverts and extraverts...occurred when stimulation was given at the appropriate optimal level," and that "the data pertaining to the measure of performance are consistent with the Yerkes-Dodson Law" (p. 1311).

Neuroticism and Visceral Brain Activation Eysenck (1990) also explains neuroticism in terms of activation thresholds in the sympathetic nervous system or visceral brain. The visceral brain is also referred to as the limbic system, which consists of the hippocampus, amygdala, septum, and hypothalamus, and regulates such emotional states as sex, fear, and aggression. It is responsible for the fight-or-flight response in the face of danger. Heart rate, blood pressure, skin conductance, sweating, breathing rate, and muscular tension in the forehead can measure activation levels of the visceral brain (Eysenck, 1990; Eysenck & Eysenck, 1985). Neurotic individuals have greater activation levels and lower thresholds within the visceral brain. They are easily upset in the face of very minor stresses. However, emotionally stable people are calm under such stresses because they have lesser activation levels and higher thresholds (Eysenck, 1990). Empirically, Ormel and Wohlfarth (1991) report that neuroticism indeed has strong influence on psychological distress. They find that "temperamental dispositions seem more powerful than environmental factors" in predicting psychological distress, and that neuroticism is a "powerful determinant" of high psychological distress (p. 753).

Psychoticism and Gonadal Hormones Eysenck (1990) also provides a biological explanation of psychoticism in terms of gonadal hormones such as testosterone and enzymes such as monoamine oxidase (MAO). Although there has not been a lot of research done on psychoticism in comparison with extraversion and neuroticism, the current research shows that people who show a psychotic episode have increased testosterone levels and low MAO levels. Impulsivity and aggressiveness were negatively correlated with MAO, which plays a role in the degradation of the monoamines norepinephrine, dopamine, and serotonin (Eysenck, 1990, 1992a). Eysenck (1992a) reports that "low platelet monoamine oxydase (MAO) has been found in psychotic patients, and also in their relatives and inpatients who have recovered, suggesting that low MAO activity may be a marker for 'vulnerability'" (p. 774).

Gray's Reformulation http://www.personalityresearch.org/papers/jang.html

4/15

11/28/2018

Contribution of Eysenck's PEN Model

Gray (1981) agrees with Eysenck's notion of hierarchical description of personality, but does not agree with the idea that extraversion and neuroticism are the defining factors of personality. Gray thinks that Eysenck's removal of the impulsivity factor from the superfactor of extraversion is a bad idea, and strongly believes that impulsivity, as well as anxiety, should be treated as a major dimension in personality. To do that, Gray reformulates Eysenck's theory by rotating the dimensions of extraversion and neuroticism by 45 degrees. This results in two new dimensions: impulsivity (Imp-D), which is high on both neuroticism and extraversion, and anxiety (Anx-D), which is high on neuroticism, but low on extraversion. According to Eysenck and Eysenck (1985), however, "it would seem preferable to locate the anxiety dimension closer to the neuroticism dimension than to that of extraversion" to accord with questionnaire measures of anxiety. Then, "impulsivity would have to be moved closer to the dimension of extraversion so that it would remain orthogonal to the dimension of anxiety" (p. 210).

BAS and BIS Gray's reformulation of Eysenck's theory also has neurological grounding and behavioral consequences. People with high impulsivity are highly sensitive to reward and non-punishment, whereas people with high anxiety are highly sensitive to signals of punishment, non-reward, and novelty. The underlying system for impulsivity is the behavioral activation system (BAS), which involves "the medial forebrain bundle and the lateral hypothalamus" (Eysenck & Eysenk, 1985, p. 211). In contrast, the underlying neurological system for anxiety is the behavioral inhibition system (BIS). The BIS consists of "an interacting set of structures comprising the septo-hippocampal system (SHS), its monoaminergic afferents from the brain stem and its neocortical projection in the frontal lobe" (Gray, 1981, p. 261). According to Gray (1981), impulsivity and anxiety are the most important dimensions of personality. Accordingly, extraversion and neuroticism are "secondary consequences of the interactions between impulsivity and anxiety systems" (p. 261). That is, a person in whom the behavioral inhibition system (BIS) of anxiety is more powerful than the behavioral activation system (BAS) of impulsivity becomes introverted, and a person in whom the BAS is relatively more powerful than the BIS becomes extraverted. Introverts, for example, are more sensitive to signals of punishment, non-reward, and novelty than they are to signals of reward and non-punishment. Thus, in Gray's perspective, the superfactor of extraversion reflects the "relative" strength of both impulsivity and anxiety, whereas neuroticism reflects their "joint" strength, in which increments in the sensitivity of either the impulsivity or anxiety system provide increments to neuroticism (p. 261). Gray's theory also predicts that extraverts will exhibit superior conditioning with a rewarding unconditioned stimulus, opposed to Eysenck's prediction of introverts' superiority in conditioning (Zinbarg & Revelle, 1989). Some research results (e.g., Anderson & Revelle, 1994; Revelle et al., 1980; Zinbarg & Revelle, 1989) indicate that impulsivity and anxiety are more consistently and strongly associated with individual differences in performance than extraversion and neuroticism. Revelle et al. (1980) reported that the administration of moderate doses of caffeine hindered the performance of introverts and helped the performance of extraverts on a cognitive task similar to the verbal test of the GRE. However, these phenomena were affected by time of day and impulsivity. In the morning, low impulsives were hindered and high impulsives helped by caffeine. But this pattern reversed in the evening. The researchers concluded that the results from the test require a revision of Eysenck's theory. Instead of a stable difference in arousal between low and high impulsives, it appeared that these groups differed in the phase of their diurnal arousal rhythms. That is, low impulsives are more aroused in the morning and less aroused in the evening than are the high impulsives. The data reported by Revelle et al. (1980) are of great importance in support of Gray's theory. Gray (1981) even called these data "a dagger that goes to the heart of Eysenckian theory" (p. 258). This http://www.personalityresearch.org/papers/jang.html

5/15

11/28/2018

Contribution of Eysenck's PEN Model

finding challenges Eysenck's arousal theory, and indicates the complexity of the interaction between personality traits and situations.

Impulsivity and Anxiety Versus Extraversion and Neuroticism Although Gray's theory is important to know for understanding impulsivity and anxiety, Eysenck's theory is undeniably the basis of Gray's reformulation. Moreover, it is too early to draw the conclusion, as Gray (1981) suggests, that impulsivity and anxiety are more important dimensions of personality than extraversion and neuroticism. More research results have to be reported on BAS and BIS. As Gray (1981) admits, "little progress has been made in descri...