"There is a strong tradition in psychology to eschew categorical in favor of dimensional thinking, a tradition in psychometrics that runs unbroken from Spearman to Eysenck. [However] if 1,000 people at random are put to work selling used cars or commanding military units, psychoanalyzing or behavior modifying, doing research or teaching sixth grade civics, we would find a J-curve and, quite possibly, a bimodal distribution of competence: just a few good sales people (some better than others), just a few charismatic leaders, a few born teachers, and a handful of truly effective therapists. Even compared with other scientists, some 5% publish 50% of the papers (D.J.Price, 1962, in B.Barber & W.Hirsch, The Sociology of Science. New York : Free Press)." D.T.LYKKEN et al., 1992, American Psychologist xii. "After decades of doubt and defensiveness, traits are back on top."