Washburn was a major figure in psychology in the United States in the first decades of the 20th century, substantially adding to the development of psychology as a science and a scholarly profession. She translated Wilhelm Wundt's "Ethical Systems" into English. Washburn used her experimental studies in animal behavior and cognition to present her idea that mental (not just behavioral) events are legitimate and important psychological areas for study in her book, "The Animal Mind" (1908). This, of course, went against the established doctrine in academic psychology that the mental was not observable and therefore not appropriate for serious scientific investigation.