A History of Modern Psychology

The study of personality arising in the United States in the 1920s and 1930s was an attempt to fuse together a number of diverse traditions, chief among which were the study of individual differences originating with Galton and the clinical study of personality begun by Freud, Jung, Adler, and their students. The European clinical psychologists had aimed to account for personality as a whole and had made it a central concept in explaining motivation. Thus, the US study, as Dan McAdams (1997) recounts, attempted to understand: 1. personality as a whole, 2. motivation, and 3. individual differences.

Wundt and the early German experimental psychologists were interested in characteristics human beings have in common; as Boring (1929/1950) noted, they studied the average adult human being. Galton had understood the role differences between individuals play in evolution, and this was his primary reason to begin the study of individual differences. The pioneers in the US study of personality were not particularly interested in the theory of evolution but were keenly interested in individuality. This focus helps explain why the study of personality became a major focus of inquiry of psychology in the United States (David Winter and Nicole Barenbaum,1999).

The emphasis on individual differences also made the US study different from earlier European work based on clinical psychology. Further, US psychologists were interested in applying the study to the selection of applicants for particular jobs in business, industry, and the military, and came to base their studies on tests and psychometric measurement. Those interested in characteristics of personality were inspired by Galton's measurements and Binet's intelligence test, and by the 1920s they had developed questionnaires and rating scales into useful instruments. When more extensive approaches were presented at the end of the 1930s, the ground had been prepared for more than a decade. This gave the study an orientation towards objective methods from the start.

Naturally, a concept covering such disparate phenomena as personality as a whole, motivation, and individual differences is not easily defined, and the editors of two comprehensive handbooks of personality (Robert Hogan et al., 1997; Lawrence Pervin and Oliver John, 1999) did not give their contributors a definition that could serve as a guideline for them or for readers.