ABSTRACT
In this last chapter an attempt has been made to bring our picture of the structure of human personality up to date by introducing certain theoretical concepts and experimental techniques which originated in an endeavour to state casual postulates from which the observed behaviour patterns and descriptive factors could be deduced in a more or less rigorous fashion. The factorial literature in the last few years has grown to such an extent that the detailed historical review which we have followed in the preceding chapters could not be maintained, without extending the book to twice its present length; such a detailed review has in fact been presented elsewhere (Eysenck and Eysenck, 1969). The main conclusion which can be drawn from the several hundred recent studies there reviewed, and the original work presented, serve largely to underlines the conclusions derived from the earlier studies discussed in the present volume; results from the different universes of discourse presented by Cattell, Guilford, the MMPI, and many other apparently separate and independent sets of investigations all support very strongly the thesis that two orthogonal personality factors, extraversion-introversion and emotionality-stability, are omnipresent in empirical studies and analyses, and account for a large and important portion of the total variance, for children as much as for adults, and for mentally ill as well as for mentally normal people. 1 Not all investigators are agreed on the nomenclature, of course, and many different terms are still used to designate these major personality variables, but it is now reasonable to say that there is almost complete agreement among experimental investigators that these two factors enjoy a predominant and assured position in the descriptive system of personality measurement.
