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.
Harry Levi Hollingworth
Harry Levi Hollingworth (May 26, 1880 – September 17, 1956) was one of the first psychologists to bring psychology into the advertising world, as well as a pioneer in applied psychology.