The Scalability of Eysenck’s Psychoticism Scale
Psychoticism is the third personality trait in the Eysenck personality model. The psychoticism scale was incorporated in the EPQ (Eysenck & Eysenck, 1975), but the greatest justification for including this personality trait was provided by Eysenck and Eysenck in their 1976 paper (Eysenck & Eysenck, 1976). In the EPQ, the psychoticism scale contained 25 items, while the revised version (EPQ-R) included 32 items (Eysenck et al., 1985). Fig. 2.2 shows the four psychoticism items included in the short-form EPQ-R but with the original EPQ item number. The content validity of these four items refers to antisocial behavior or risk-taking behavior.
The psychoticism items listed at the bottom in Fig. 2.2 are the EPQ items identified by Kendler, Heath, and Martin (1987) as measuring suspiciousness components of psychoticism. These items identified by Kendler et al. (1987) are related to psychoticism in a higher degree than those of the other four items (Fig. 2.2), which cover risk-taking behavior, a behavior also included in hypomania screening questionnaires (Bech, Christensen, Vinberg, BechAndersen, & Kessing, 2011).
Per Bech, in Personality and Disease, 2018