fei75766_ch14_435-462.indd 437  02/06/20 01:10 PM
Chapter 14    Eysenck’s Biologically Based Factor Theory437
Chance andfortuity often playadecisive roleinpeople’s lives. Onesuchchance 
event happened toan18-year-old German youth whohadlefthisnative coun -
tryasaconsequence ofNazi tyranny. Heeventually settled inEngland, where he
tried toenroll intheUniversity ofLondon. Hewasanavidreader, interested in
boththeartsandthesciences, buthisfirstchoice ofcurriculum wasphysics. 
However, achance event altered theflowofhislifeandconsequently the
course ofthehistory ofpsychology. Inorder tobeaccepted intotheuniversity, he
wasrequired topassanentrance examination, which hetookafterayear’s study ata
commercial college. After passing theexam, heconfidently enrolled intheUniversity 
ofLondon, intending tomajor inphysics. However, hewastoldthathehadtaken 
thewrong subjects inhisentrance exam andtherefore wasnoteligible topursue a
physics curriculum. Rather thanwaiting another yeartotaketherightsubjects, he
asked ifthere wassome scientific subject thathewasqualified topursue. When told
hecould always takepsychology, heasked, “What onearth ispsychology?” Hehad
never heard ofpsychology, although hehadsome vague ideaabout psychoanalysis. 
Could psychology possibly beascience? However, hehadlittlechoice buttopursue 
adegree inpsychology, sohepromptly entered theuniversity withamajor inadis-
cipline about which heknew almost nothing. Years later,theworld ofpsychology 
would know agreat dealabout Hans J.Eysenck, probably themost prolific writer in
thehistory ofpsychology. Inhisautobiography, Eysenck (1997b) simply noted that
bysuchchance events “isone’s fatedecided bybureaucratic stupidity” (p.47).
Throughout hislife,Eysenck battled bureaucratic stupidity andanyother type
ofstupidity hecame across. Inhisautobiography, hedescribed himself as“asancti -
monious prig...whodidn’t suffer fools (orevenordinarily bright people) gladly” 
(Eysenck, 1997b, p.31).
Overview of Biologically Based  
Trait Theory
Every theory ofpersonality discussed sofarhasdownplayed, ignored, oreven 
argued against thebiological basis ofhuman personality. Only McCrae and
Costa (seeChapter 13)placed even mild emphasis ongenetic andbiological 
influences onpersonality. 
With Eysenck thatchanged. Eysenck developed afactor theory much like
McCrae andCosta, butbecause hefundamentally based histaxonomy inboth
factor analysis andbiology, hederived onlythree, rather thanfive,dimensions 
ofpersonality—extraversion/introversion, neuroticism/stability, andpsychoticism/
superego. We’ll discuss these more laterinthechapter, butthekeyforEysenck 
wasthattheindividual differences inpeople’s personalities were biological, and
notmerely psychological, aspects ofpersonality. That is,genetic differences leadto
structural differences inthecentral nervous system, including brain structures, hor-
mones, andneurotransmitters, andthese differences inbiology leadtodifferences 
along thethree factors ofpersonality—extraversion, neuroticism, andpsychoticism.
Evidence forthebiological basis ofpersonality comes from many different 
sources, including temperament, behavioral genetics, andbrain measure research. 
First, temperament isthebiologically based tendency tobehave inparticular Final PDF to printer