fei75766_ch14_435-462.indd 448  02/06/20 01:10 PM
Part V    Biological/Evolutionary Theories448
neuroticism. Asscores move toward theouter limits ofthediagram, theybecome 
increasingly lessfrequent, justasscores ontheendsofabell-shaped curve areless
frequent thanthose nearthemidpoint.
Psychoticism
Eysenck’s original theory ofpersonality wasbased ononlytwopersonality 
dimensions—extraversion andneuroticism. After several years ofalluding topsychoti -
cism(P)asanindependent personality factor, Eysenck finally elevated ittoaposition 
equal toEandN(Eysenck &Eysenck, 1976). Likeextraversion andneuroticism, P
isabipolar factor, withpsychoticism ononepoleandsuperego ontheother. High P
scorers areoften egocentric, cold, nonconforming, impulsive, hostile, aggressive, sus-
picious, psychopathic, andantisocial. People lowonpsychoticism (inthedirection of
superego function) tendtobealtruistic, highly socialized, empathic, caring, coopera -
tive,conforming, andconventional (Eysenck, 1997). 
Earlier, wesawthatEysenck accepted thediathesis-stress model forpeople 
highontheneuroticism scale; thatis,stress andhighNscores combine toelevate 
people’s vulnerability topsychological disorders. Thismodel alsosuggests thatpeople 
whoscore highonpsychoticism andwhoarealsoexperiencing levels ofstress have
anincreased chance ofdeveloping apsychotic disorder. Eysenck (1994a) hypoth -
esized thatpeople highonpsychoticism haveahigh“predisposition tosuccumb to
stress anddevelop apsychotic illness” (p.20).Thisdiathesis-stress model suggests 
thathighPscorers aregenetically more vulnerable tostress thanarelowPscorers. 
During periods oflittlestress, highPscorers mayfunction normally, butwhen high
psychoticism interacts withhighlevels ofstress, people become vulnerable topsy-
chotic disorders. Bycontrast, people withlowPscores arenotnecessarily vulnerable 
tostress-related psychoses andwillresist apsychotic break eveninperiods ofextreme Neuroticism
A
EDB C
StabilityExtraversionIntroversion
FIGURE 14.4  Two-Dimensional 
Scheme Depicting Several Extreme 
Points on Eysenck ’s E and N Scales.Final PDF to printer