fei75766_ch14_435-462.indd 447  02/06/20 01:10 PM
Chapter 14    Eysenck’s Biologically Based Factor Theory447
Neuroticism
Thesecond superfactor extracted byEysenck isneuroticism/stability (N).Likeextra -
version/introversion, Factor Nhasastrong hereditary component. Eysenck (1967) 
reported several studies thathavefound evidence ofagenetic basis forsuchneurotic 
traits asanxiety, hysteria, andobsessive–compulsive disorders. Inaddition, hefound 
amuch greater agreement among identical twins thanamong fraternal twins ona
number ofantisocial andasocial behaviors suchasadult crime, childhood behavior 
disorders, homosexuality, andalcoholism (Eysenck, 1964).
People whoscore highonneuroticism often haveatendency tooverreact emo-
tionally andhavedifficulty returning toanormal stateafteremotional arousal. They 
frequently complain ofphysical symptoms suchasheadache andbackache andof
vague psychological problems suchasworries andanxieties. Eysenck (1967, 1982) 
proposed thisemotional reactivity inneuroticism isduetohaving ahighly reac-
tivelimbic system, including theamgydala andhypothalamus. Neuroticism, how-
ever, doesnotnecessarily suggest aneurosis inthetraditional meaning ofthatterm. 
People canscore highonneuroticism andbefreeofanydebilitating psychological 
symptoms.
Eysenck accepted thediathesis-stress model ofpsychiatric illness, which sug-
gests thatsome people arevulnerable toillness because theyhaveeither agenetic or
anacquired weakness thatpredisposes them toanillness. Thispredisposition (dia-
thesis) mayinteract withstress toproduce aneurotic disorder. Eysenck assumed that
people atthehealthy endoftheNscale havethecapacity toresist aneurotic disorder 
eveninperiods ofextreme stress. High Nscorers, however, maysuffer aneurotic reac-
tionasaresult ofonlyaminimal levelofstress. Inother words, thehigher theneuroti -
cismscore, thelower thelevelofstress necessary toprecipitate aneurotic disorder.
Because neuroticism canbecombined withdifferent points ontheextraver -
sionscale, nosingle syndrome candefine neurotic behavior. Eysenck’s factor analytic 
technique assumes theindependence offactors, which means thattheneuroticism 
scale isatrightangles (signifying zerocorrelation) totheextraversion scale. Thus, 
several people canallscore highontheNscale yetdisplay quite different symp -
toms, depending ontheirdegree ofintroversion orextraversion. Figure 14.4shows 
theextraversion/introversion polewithzerocorrelation withtheneuroticism/stability 
pole. Consider Persons A,B,andC,allequally highontheneuroticism scale, but
representing three distinct points ontheextraversion scale. Person A,anintroverted 
neurotic, ischaracterized byanxiety, depression, phobias, andobsessive–compulsive 
symptoms; Person B,whoishighonneuroticism butonlyaverage onextraversion, is
likely tobecharacterized byhysteria (aneurotic disorder associated withemotional 
instability), suggestibility, andsomatic symptoms; andPerson C,anextraverted neu-
roticindividual, willprobably manifest psychopathic qualities suchascriminality and
delinquent tendencies (Eysenck, 1967, 1997a). Consider, also,Persons A,D,andE,
allequally introverted, butwiththree different levels ofemotional stability. Person 
Aistheintroverted neurotic individual wejustdescribed; Person Disequally intro -
verted butisneither severely neurotic noremotionally stable; andPerson Eisboth
extremely introverted andpsychologically stable.
Figure 14.4shows onlyfivepeople, allofwhom haveatleastoneextreme 
score. Most people, ofcourse, would score nearthemean onbothextraversion andFinal PDF to printer