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.
Muzafer Sherif
Sherif was a founder of modern social psychology who developed several unique and powerful techniques for understanding social processes, particularly social norms and social conflict. Many of his original contributions to social psychology have been absorbed into the field so fully that his role in the development and discovery has disappeared. Other reformulations of social psychology have taken his contributions for granted, and re-presented his ideas as new.