fei75766_ch14_435-462.indd 450  02/06/20 01:10 PM
Part V    Biological/Evolutionary Theories450
TheEPIwasstillatwo-factor inventory, soconsequently Hans Eysenck and
Sybil Eysenck (1975) published athird personality test,namely theEysenck Person -
alityQuestionnaire (EPQ), which included apsychoticism (P)scale. TheEPQ, which 
hasbothanadult version andajunior version, isarevision ofthestill-published EPI.
Subsequent criticisms ofthePscale ledtoyetanother revision, theEysenck Personal -
ityQuestionnaire-Revised (H.J.Eysenck &S.B.G.Eysenck, 1993).
Biological Bases of Personality
According toEysenck, personality factors P,E,andNallhavepowerful biological 
determinants. Heestimated thatabout three -fourths ofthevariance ofallthree per-
sonality dimensions canbeaccounted forbyheredity andabout onefourth byenvi-
ronmental factors. 
Eysenck (1990) citedthree threads ofevidence forastrong biological component 
inpersonality. First, researchers (McCrae &Allik, 2002) havefound nearly identical 
factors among people invarious parts oftheworld, notonlyinWestern Europe and
North America butalsoinUganda, Nigeria, Japan, China, Russia, andother African 
andEuropean countries. Second, evidence (McCrae &Costa, 2003) suggests thatindi-
viduals tendtomaintain theirposition overtimeonthedifferent dimensions ofperson -
ality.Andthird, studies oftwins (Eysenck, 1990) show ahigher concordance between 
identical twins thanbetween same-gender fraternal twins reared together, suggesting that
genetic factors playadominant partindetermining individual differences inpersonality.
InEysenck’s theory ofpersonality, psychoticism, extraversion, andneuroti -
cismhavebothantecedents andconsequences. Theantecedents aregenetic and
biological, whereas theconsequences include suchexperimental variables ascon-
ditioning experiences, sensitivity, andmemory aswellassocial behaviors suchas
criminality, creativity, psychopathology, andsexual behavior. Figure 14.6shows that
DNALimbic
system
arousalP
E
NPersonality
Conditioning
Sensitivity
Vigilance
Perception
Memory
ReminiscenceSociability
Criminality
Creativity
Psychopathology
Sexual behaviorDistal
antecedentsProximal
antecedentsProximal
consequencesDistal
consequences
Genetic
personality
determinantsPsychometric
trait
constellationsBiological
intermediariesExperimental
studiesSocial
behavior
FIGURE 14.6  A Model of the Major Components of Eysenck ’s Theory of Personality.Final PDF to printer