High levels of this trait were believed by Eysenck to be linked to increased vulnerability to
psychosessuch as schizophrenia. He also believed that blood relatives of psychotics would show high levels of this trait, suggesting a genetic basis to the trait.
Critics of the trait have suggested that the trait is too heterogeneous to be taken as a single trait. For example, In a correlation study by Donald Johnson (reported in 1994 at the APT International Conference) Psychoticism was found to correlate with Big Five traits Conscientiousness and Agreeableness; (which in turn correlated strongly with, respectively,
MBTIJudging/Perceiving, and Thinking/Feeling).Fact|date=October 2007 Thus, Costa and McCrae believe that agreeableness and conscientiousness (both which represent low levels of psychoticism) need to be distinguished in personality models. Eysenck also argued that there might be a correlation between psychoticism and creativityEysenck, Hans J. (1993). Creativity and Personality: Suggestions for a Theory. "Psychological Inquiry". 4(3), 147-178.] .
Biological bases of psychoticism
Psychoticism is believed to be associated with levels of
dopamine(Lester, 1989).Other biological correlates of psychoticism include low conditionability and low levels of monoamine oxidase; beta-hydroxylase, cortisol, norepinephrinein cerebrospinal fluidalso appear relevant to psychoticism level.
Eysenck's theoretical basis for the model was the theory of "
Einheitspsychosen" of the nineteenth-century German psychiatrist Heinrich Neumann.
*Lester, D.(1989)Neurotransmitter bases for Eysenck's theory of personality. Psychological Reports, 64, (1) 189-190
*Eysenck, H.J. & Eysenck, S.B.G. (1976). "Psychoticism as a Dimension of Personality." London: Hodder and Stoughton
*Costa, Paul T. & McCrae, Robert R. (1995). "Primary traits of Eysenck's P-E-N system: Three- and five-factor solutions."
Journal of Personality and Social Psychology. 69(2), Aug 1995, 308-317.
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