He expanded the Stimulus-Response model of behavior of the Behaviorist school, adding the organism (Stimulus-Organism-Response) as having a defining role in determining its own behavior. Woodworth also developed the interactionist model of "nature vs. nurture to allow both innate, hereditary factors and experience in the world to play roles in psychological development. While Woodworth's name may not be as famous as other psychologists, this work laid the foundation for the greatest advances in understanding human behavior.