Story of Psychology - Morton Hunt [211]
A number of psychologists suggested making order out of chaos by grouping allied traits into larger tendencies or syndromes such as “general activity,” “sense of well-being,” and “emotional stability,” or into such psychodynamic syndromes as aggressiveness and oral or anal tendencies. Others recommended sorting personalities into bimodal categories or types, like Jung’s division of people into the extraverted and the introverted.
But such terms were vague catchalls; researchers wanted rigorous evidence that traits cohered in clear-cut, identifiable clusters. And a way to gather such evidence did exist. Galton had discovered correlation analysis, the statistical procedure for measuring co-variance (the degree to which one variable, like a trait, increases or decreases when another does). Then the English psychologist and statistician Charles Spearman had developed the more sophisticated technique known as factor analysis to measure, simultaneously, the correlations among a whole group of variables—exactly what was needed to make sense of trait data. The method is complicated but its basic concept is simple. If a number of traits all co-vary—that is, if a higher or lower score in any trait is accompanied by somewhat higher or lower scores in the others—it is reasonable to suppose that they are all influenced by an underlying general tendency or factor.
An intriguing application of factor analysis to personality was made during the 1940s by Hans J. Eysenck (1916–1997), a German-born psychologist who, though not Jewish, left Germany after it came under Nazi domination and became a British citizen. Adopting Jung’s two-part typology, Eysenck hypothesized that a number of traits such as rigidity and shyness would be strongly correlated in introverted people and that opposite traits would be as strongly correlated in extraverted people. To this he added another two-part typology of his own, the dimension of neuroticism, with highly stable personalities at one extreme and highly unstable ones at the other; again, he expected certain traits to be associated with each.
When he put his suppositions to the statistical test, using trait data yielded by the MMPI and a personality test of his own devising, he found them confirmed: there were indeed correlations among the traits he thought should be clustered in introverts and in extraverts, and comparable correlations among those he expected to find clustered in neurotics and in mentally healthy people. When he plotted out these four factors, they bore an astonishing resemblance to the four temperaments of Galen’s ancient humoral theory. Eysenck, normally an outspoken maverick, was untypically cautious about this coincidence:
It is easy to read into historical writings what one wishes to see, and particularly to interpret ancient terms in line with modern connotations. Nevertheless, there do appear to be certain similarities between these early speculators and the more modern work [of others and of Eysenck himself].40
With this caveat, he offered the following diagram:41
FIGURE 16
Eysenck’s fourfold personality table
As fascinating as the coincidence was, most users of the MMPI found Eysenck’s fourfold typology too general; they hoped to extract more specific and detailed diagnoses from the many scores the test yielded. Such diagnoses were made possible by a different use of factor analysis developed over several decades of unremitting work by the English-born psychologist, Raymond B. Cattell (1905–1998), mentioned earlier. Cat-tell was far more cautious and methodical than Eysenck; instead of beginning with hypothesized conclusions, as Eysenck had, he let factor analysis lead the way. He computed the correlations among a large number of variables, assembled lists of those which showed significant correlations, and gave them the names of factors. It was an onerous task, even with the help of computers; to calculate all the possible correlations of a hundred variables, for instance, one would need to