This is the original work on which Hans Eysenck''s fifty years of research have been built. It introduced many new ideas about the nature and measurement of personality into the field, related personality to abnormal psychology, and demonstrated the possibility of testing personality theory experimentally. The book is the result of a concentrated and cooperative effort to discover the main dimensions of personality, and to define them operationally, that is, by means of strictly experimental, quantitative procedures. More than three dozen separate researches were carried out on some 10,000 normal and neurotic subjects by a research team of psychologists and psychiatrists. A special feature of this work is the close collaboration between psychologists and psychiatrists. Eysenck believes that the exploration of personality would have reached an advanced state much earlier had such a collaboration been the rule rather than the exception in studies of this kind. Both disciplines benefit
