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.
Functional psychology
William James is considered to be the founder of functional psychology. But he would not consider himself as a functionalist, nor did he truly like the way science divided itself into schools. John Dewey, George Herbert Mead, Harvey A. Carr, and especially James Rowland Angell were the main proponents of functionalism at the University of Chicago. Another group at Columbia, including notably James McKeen Cattell, Edward L. Thorndike, and Robert S. Woodworth, were also considered functionalists and shared some of the opinions of Chicago's professors. Egon Brunswik represents a more recent, but Continental, version. The functionalists retained an emphasis on conscious experience.