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.
Morris Viteles
Morris Simon Viteles (March 21, 1898 - December 7, 1996) was an influential researcher and writer in the field of industrial and organizational psychology. His book "Industrial Psychology", published in 1932, was the first comprehensive modern textbook in the field. His writings were so influential that he was often regarded as the founder of the field, although he disavowed that claim.