Editing Trait theory (section)

==Comparing EPQ and Big Five==

===Testing methodology, and factors===
Both the EPQ and Big Five approaches extensively use self-report questionnaires. The factors are intended to be [[orthogonal]] (uncorrelated),<ref>{{cite book|author-link=Hans Eysenck|first=Hans|last=Eysenck|year=1990|chapter=Biological dimensions of personality|editor-first=L. A.|editor-last=Pervin|title=Handbook of personality: Theory and research|pages=244–76|location=New York|publisher=Guilford|name-list-style=vanc}}</ref> though there are often small positive [[correlations]] between factors. The five factor model in particular has been criticized for losing the orthogonal structure between factors.<ref>{{multiref2
|1={{cite journal | last1 = Block | first1 = J. | year = 1995 | title = A contrarian view of the five-factor approach to personality description | journal = Psychological Bulletin | volume = 117 | issue = 2| pages = 187–215 | doi=10.1037/0033-2909.117.2.187 | pmid=7724687|name-list-style=vanc}}
|2={{cite journal | last1 = Draycott | first1 = S. G. | last2 = Kline | first2 = P. | year = 1995 | title = The Big Three or the Big Five—the EPQ-R vs the NEO-PI: a research note, replication and elaboration | journal = Personality and Individual Differences | volume = 18 | issue = 6| pages = 801–804 | doi=10.1016/0191-8869(95)00010-4|name-list-style=vanc}}
}}</ref> British psychologist [[Hans Eysenck]] has argued that fewer factors are superior to a larger number of partly related ones.<ref>{{cite journal | last1 = Eysenck | first1 = H. J. | year = 1992 | title = A reply to Costa and McCrae. P or A and C: The role of theory | journal = Personality and Individual Differences | volume = 13 | issue = 8| pages = 867–868 | doi=10.1016/0191-8869(92)90003-8|name-list-style=vanc}}</ref> Although these two approaches are comparable because of the use of factor analysis to construct hierarchical taxonomies, they differ in the organization and number of factors.

Whatever the causes, [[psychoticism]] marks the two approaches apart, as the five factor model contains no such trait. Moreover, psychoticism, unlike any of the other factors in either approach, does not fit a [[normal distribution curve]]. Indeed, scores are rarely high, thus skewing a [[normal distribution]].<ref name="Personality traits"/> However, when they are high, there is considerable overlap with psychiatric conditions such as [[Psychopathy|antisocial]] and [[schizoid personality disorder]]s. Similarly, high scorers on [[neuroticism]] are more susceptible to [[sleep]] and [[psychosomatic]] disorders.<ref>{{cite book|author-link1=Hans Eysenck|first1=Hans|last1=Eysenck|first2=S. B. G.|last2=Eysenck|year=1991|title=The Eysenck Personality Questionnaire-Revised|location=Sevenoaks|publisher=Hodder & Stoughton|name-list-style=vanc}}</ref> Five factor approaches can also predict future mental disorders.<ref>{{multiref2
|1={{cite journal | last1 = Costa | first1 = P. T. | last2 = McCrae | first2 = R. R. | year = 1990 | title = Personality disorders and the five factor model of personality | journal = Journal of Personality Disorders | volume = 4 | issue = 4| pages = 362–371 | doi=10.1521/pedi.1990.4.4.362|name-list-style=vanc}}
|2={{cite journal | last1 = Lynam | first1 = D. R. | last2 = Caspi | first2 = A. | last3 = Moffitt | first3 = T. E. | last4 = Raine | first4 = A. | last5 = Loeber | first5 = R. | last6 = Stouthamer-Loeber | first6 = M. | year = 2005 | title = Adolescent psychopathy and the Big Five: Results from two samples | journal = Journal of Abnormal Child Psychology | volume = 33 | issue = 4| pages = 431–443 | doi=10.1007/s10648-005-5724-0| pmid = 16118990 | s2cid = 24240140|name-list-style=vanc}}
}}</ref>

=== Lower-order factors ===
[[File:Factors.svg|thumb|right|250px|Similarities between lower-order factors for psychoticism and the [[Facet (psychology)|facets]] of openness, agreeableness, and conscientiousness (from Matthews, Deary & Whiteman, 2003)]]

There are two higher-order factors that both taxonomies clearly share: [[extraversion]] and [[neuroticism]]. Both approaches broadly accept that extraversion is associated with [[sociability]] and positive [[dispositional affect|affect]], whereas [[neuroticism]] is associated with emotional instability and negative affect.<ref name="Personality traits">{{cite book|last1=Matthews|first1=G.|last2=Deary|first2=I. J.|last3=Whiteman|first3=M. C.|year=2003|title=Personality traits|edition=2nd|location=Cambridge|publisher=Cambridge University Press|name-list-style=vanc}}</ref>

Many lower-order factors, or [[Facet (psychology)|facets]], are similar between the two taxonomies. For instance, both approaches contain factors for sociability/gregariousness, for activity levels, and for assertiveness within the higher order factor extraversion. However, there are differences too. First, the three-factor approach contains nine lower-order factors and the five-factor approach has six.<ref name="Personality traits"/>

Eysenck's [[psychoticism]] factor incorporates some of the [[orthogonal|polar opposites]] of the lower order factors of openness, agreeableness and conscientiousness. A high scorer on tough-mindedness in [[psychoticism]] would score low on tender-mindedness in agreeableness. Most of the differences between the taxonomies stem from the three factor model's emphasis on fewer high-order factors.

===Causality===
Although both major trait models are descriptive, only the three-factor model offers a detailed causal explanation. Eysenck suggests that different personality traits are caused by the properties of the [[brain]], which themselves are the result of [[Genetics|genetic]] factors.<ref>{{cite book|last1=Eysenck|first1=H. J.|last2=Eysenck|first2=M. W.|year=1985|title=Personality and individual differences: A natural science approach|location=New York|publisher=Plenum|name-list-style=vanc}}</ref> In particular, the three-factor model identifies the [[reticular system]] and the [[limbic system]] in the brain as key components that mediate cortical arousal and emotional responses respectively. Eysenck advocates that extraverts have low levels of cortical arousal and introverts have high levels, leading extraverts to seek out more stimulation from socializing and being venturesome.<ref>{{cite book|last=Eysenck|first=H. J.|year=1967|title=The biological basis of personality|location=Springfield, Ill.|publisher=Thomas|name-list-style=vanc}}</ref> Moreover, Eysenck surmised that there would be an optimal level of arousal, after which inhibition would occur and that this would be different for each person.<ref>{{cite journal | last1 = Eysenck | first1 = H. J. | year = 1994 | title = Creativity and personality: Word association, origence, and Psychoticism | journal = Creativity Research Journal | volume = 7 | issue = 2| pages = 209–216 | doi=10.1080/10400419409534525|name-list-style=vanc}}</ref>

In a similar vein, the three-factor approach theorizes that neuroticism is mediated by levels of arousal in the limbic system and that individual differences arise because of variable activation thresholds between people. Therefore, highly neurotic people when presented with minor stressors, will exceed this threshold, whereas people low in neuroticism will not exceed normal activation levels, even when presented with large stressors. By contrast, proponents of the five-factor approach assume a role of [[genetics]]<ref name="Costa1992"/> and environment<ref name="Jeronimus2014"/> but offer no explicit causal explanation.

Given this emphasis on [[biology]] in the three-factor approach, it would be expected that the third trait, psychoticism, would have a similar explanation. However, the causal properties of this state are not well defined. Eysenck has suggested that psychoticism is related to [[testosterone]] levels and is an inverse function of the [[Serotonin|serotonergic system]],<ref>{{cite journal | last1 = Eysenck | first1 = H. J. | year = 1992 | title = The definition and measurement of psychoticism | journal = Personality and Individual Differences | volume = 13 | issue = 7| pages = 757–785 | doi=10.1016/0191-8869(92)90050-y|name-list-style=vanc}}</ref> but he later revised this, linking it instead to the [[dopaminergic system]].<ref>{{cite journal | last1 = Eysenck | first1 = H. J. | year = 1997 | title = Personality and experimental psychology: The unification of psychology and the possibility of a paradigm | journal = Journal of Personality and Social Psychology | volume = 73 | issue = 6| pages = 1224–1237 | doi=10.1037/0022-3514.73.6.1224|name-list-style=vanc}}</ref>