Part I    Introduction16
fei75766_ch01_001-018.indd 16  02/06/20 10:41 AMInbuilding atheory ofpersonality, psychologists should begin onalimited 
scale andavoid sweeping generalizations thatattempt toexplain allofhuman behav -
ior.Thatcourse ofaction wasfollowed bymost ofthetheorists discussed inthis
book. Forexample, Freud began withatheory based largely onhysterical neuroses 
and,overaperiod ofyears, gradually expanded ittoinclude more andmore ofthe
totalpersonality.
Research in Personality Theory
Aswepointed outearlier, theprimary criterion forauseful theory isitsability to
generate research. Wealsonoted thattheories andresearch datahaveacyclic rela-
tionship: Theory gives meaning todata, anddataresult from experimental research 
designed totesthypotheses generated bythetheory. Notalldata, however, flowfrom 
experimental research. Much ofitcomes from observations thateachofusmake 
every day.Toobserve simply means tonotice something, topayattention.
Youhavebeen observing human personalities fornearly aslongasyouhave
been alive. Younotice thatsome people aretalkative andoutgoing; others arequiet 
andreserved. Youmayhaveevenlabeled suchpeople asextraverts andintroverts. 
Arethese labels accurate? Isoneextraverted person likeanother? Does anextravert 
always actinatalkative, outgoing manner? Canallpeople beclassified aseither intro -
verts orextraverts?
Inmaking observations andasking questions, youaredoing some ofthesame 
things psychologists do,thatis,observing human behaviors andtrying tomake sense 
ofthese observations. However, psychologists, likeother scientists, trytobesystem -
aticsothattheirpredictions willbeconsistent andaccurate.
Toimprove theirability topredict, personality psychologists havedeveloped 
anumber ofassessment techniques, including personality inventories. Much ofthe
research reported intheremaining chapters ofthisbook hasrelied onvarious assess -
ment procedures, which purport tomeasure different dimensions ofpersonality. For
these instruments tobeuseful theymust bebothreliable andvalid. Thereliability ofa
measuring instrument istheextent towhich ityields consistent results.
Personality inventories maybereliable andyetlackvalidity oraccuracy. 
Validity isthedegree towhich aninstrument measures what itissupposed tomea-
sure. Personality psychologists areprimarily concerned withtwotypes ofvalidity—
construct validity andpredictive validity. Construct validity istheextent towhich 
aninstrument measures some hypothetical construct. Constructs suchasextraver -
sion, aggressiveness, intelligence, andemotional stability havenophysical existence; 
theyarehypothetical constructs thatshould relate toobservable behavior. Three 
important types ofconstruct validity areconvergent validity, divergent validity, and
discriminant validity. Ameasuring instrument hasconvergent construct validity to
theextent thatscores onthatinstrument correlate highly (converge) withscores on
avariety ofvalid measures ofthatsame construct. Forexample, apersonality inven -
torythatattempts tomeasure extraversion should correlate withother measures of
extraversion orother factors suchassociability andassertiveness thatareknown to
cluster together withextraversion. Aninventory hasdivergent construct validity if
ithasloworinsignificant correlations withother inventories thatdonotmeasure Final PDF to printer