(1934)
Curtis' WF-4 part of his model offers a theoretical framework of psychology, connecting human behavior to a larger "personality-conformity" framework. This framework views a person's psychological processes as a combination of traits, or both acquired and intrinsic personality tendencies, combined with environmental influences. In this way, the WF-4 (Wiener-Freud Four Factor Model) helps explain why different individuals respond to the same environment in different ways. Furthermore, Curtis suggested that this information could be used to better understand how external influences—such as family, education, society, and culture—affect human behavior, and also how individuals may best adjust to different environments.