ABSTRACT
Over three decades ago, Cronbach (1957) pronounced the “Two disciplines of scientific psychology.” This provocative article recognized a division between the “experimental” school and the “differential” school of psychology. Cronbach (1957; 1975) called for the merger of these two separate disciplines, and he advocated the “aptitude by treatment interaction” (ATI) methodology as the integrative device. It seems to me that this pronouncement had the unfortunate side effect of providing justifications for the continued separation of these different approaches to the analysis of human behavior. That is, psychological researchers took even more pride in labeling themselves as either an “experimentalist” or a “correlationalist.” This question of personal identity is often asked today. This poses some problems for those of us who have attended many schools of psychology and see benefits within and between several approaches. So our task remains—we need to demonstrate the benefits of such a merger for psychology.
