Three Personality Supertraits:

Eysenck (1916-1997) believed initially that all people could be described in terms of two supertraits, which he believed had a biological basis:

Introversion-extraversion (continuum of sociability, dominance, liveliness etc)

Emotionality-stability (neuroticism) (continuum of upset and distress)

Psychoticism added later: less researched. This was a predisposition towards becoming either psychotic or sociopathic (psychologically unattached to other people). Also, a tendency to be hostile, manipulative, and impulsive.

Eysenck designed the Eysenck Personality Questionnaire (EPQ).

A second-order Factor Analysis of Cattell's 16PF shows two factors: introversion/extraversion and anxiety. So the underlying factors of Cattell’s scales are very similar to Eysenck’s.

An example of the research supporting the supertraits was a 1968 study by Giese and Schmidt with a
group of college students over the age of 19 (reported by Eysenck, 1973) in which extraversion strongly predicted age of first experiencing sexual intercourse.