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.
Edward C. Tolman
Edward Chace Tolman (April 14, 1886 – November 19, 1959) was an American psychologist. Through Tolman's theories and works, he founded what is now a branch of psychology known as purposive behaviorism. Tolman also promoted the concept known as latent learning first coined by Blodgett (1929). A "Review of General Psychology" survey, published in 2002, ranked Tolman as the 45th most cited psychologist of the 20th century.