Raymond Cattell biog.

A person's behaviour is motivated by these core traits. Allport had, in his original study, filtered the Dictionary and removed all words that described in some way human behaviour. Cattell found that most of these words were similar, if not identical in their meaning. Cattell's list of core traits consisted of a collect trait to describe a surface manifestation. For example, the Core trait of Ego Strength can be used to describe various surface attributes a person might be stated as having, such as honesty, self-discipline and thoughtfulness (Engler.B, 1999). Knowledge of source traits, i.e. the motivating forces of an individual's behaviour, Cattell hypothesized, could therefore lead to predictions into the likelihood an individual would act in a certain way due to their personality disposition, thus Cattell thought that an individuals behaviour could be predicted by their personality. Via the technique of factor analysis, which Cattell learnt under Spearman in his earlier studies, Cattell minimised Allport's original somewhat overwhelming list of personality description to what he claimed to be his conclusive 16 source personality character traits. Each of the traits, as stated earlier in Cattell's theory, was complimentary, an individual would be either more outgoing then he would be reserved, or vice versa, they might be more happy-go-lucky then sober, they might be more self sufficient then group minded etc. .
             As earlier stated, Cattell went beyond the behaviouralists perspective and believed that there were internal building blocks of source traits that were the motivation of a humans behaviour. As these were observable only via the manifestation of surface traits an individual possessed, Cattell attempted to create a empirically valid personality test that would derive these source traits through the manipulative extraction of surface traits. In Cattell's 16 Pf (i.e. 16 personality factor test), Cattell presented a collection of true or false questions, each with a contextual basis relating to a certain set of traits.