Theories of Personality 9th Edition

Chapter 14 Eysenck’s Biologically Based Factor Theory 419

technique assumes the independence of factors, which means that the neuroticism
scale is at right angles (signifying zero correlation) to the extraversion scale. Thus,
several people can all score high on the N scale yet display quite different symptoms,
depending on their degree of introversion or extraversion. Figure 14.3 shows the
extraversion/introversion pole with zero correlation with the neuroticism/stability
pole. Consider persons A, B, and C, all equally high on the neuroticism scale, but
representing three distinct points on the extraversion scale. Person A, an introverted
neurotic, is characterized by anxiety, depression, phobias, and obsessive-compulsive
symptoms; Person B, who is high on neuroticism but only average on extraversion,
is likely to be characterized by hysteria (a neurotic disorder associated with emotional
instability), suggestibility, and somatic symptoms; Person C, an extraverted neurotic
individual, will probably manifest psychopathic qualities such as criminality and
delinquent tendencies (Eysenck, 1967, 1997a). Consider, also, Persons A, D, and E,
all equally introverted, but with three different levels of emotional stability. Person
A is the introverted neurotic individual we just described; Person D is equally intro-
verted but is neither severely neurotic nor emotionally stable; and Person E is both
extremely introverted and psychologically stable.
Figure 14.3 shows only five people, all of whom have at least one extreme
score. Most people, of course, would score near the mean on both extraversion and
neuroticism. As scores move toward the outer limits of the diagram, they become
increasingly less frequent, just as scores on the ends of a bell-shaped curve are
less frequent than those near the midpoint.

Psychoticism

Eysenck’s original theory of personality was based on only two personality dimensions—
extraversion and neuroticism. After several years of alluding to psychoticism (P) as an
independent personality factor, Eysenck finally elevated it to a position equal to E and

Neuroticism

A

E

D

B C

Stability

Extraversion

Introversion

FIGURE 14.3 Two-dimensional
scheme depicting several extreme
points on Eysenck’s E and N scales.