Gustav Fechner
Fechner, along with Wilhelm Wundt and Hermann von Helmholtz, is recognized as one of the founders of modern experimental psychology. His clearest contribution was the demonstration that because the mind was susceptible to measurement and mathematical treatment, psychology had the potential to become a quantified science. Theorists such as Immanuel Kant had long stated that this was impossible, and that therefore, a science of psychology was also impossible.
Elliot Aronson
Elliot Aronson (born January 9, 1932) is an American psychologist who is best known for his experiments on the theory of cognitive dissonance and for his invention of the Jigsaw Classroom, a cooperative teaching technique which facilitates learning while reducing interethnic hostility and prejudice. In his popular (1972) social psychology textbook, "The Social Animal," (now in its 11th edition), he stated Aronson's First Law: "People who do crazy things are not necessarily crazy," thus asserting the importance of situational factors in bizarre behavior. He is the only person in the 120-year history of the American Psychological Association to have won all three of its major awards: for writing, for teaching, and for research. In 2007 he received the William James Award for Lifetime Achievement from the Association for Psychological Science, in which he was cited as the scientist who "fundamentally changed the way we look at everyday life.” A "Review of General Psychology" survey, published in 2002, ranked Aronson as the 78th most cited psychologist of the 20th century. He officially retired in 1994 but continues to teach and write.