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.
Donald R. Peterson
Donald R. Peterson (September 10, 1923 – November 2, 2007) was professor emeritus of psychology at Rutgers University. Dr. Peterson was notable for advocating for a professional doctorate exclusive to professional psychologists, eventually leading to establishment of the Doctor of Psychology degree and programs. Establishing this degree as the standard doctorate for practicing psychologists was not embraced by most psychologists, who were concerned programs would abandon scientific principles in the name of greater clinical training. While Psy.D. programs are more likely to produce practitioners, this degree and research productivity are not mutually exclusive, and a number of psychologists holding the Doctor of Psychology degree have contributed significantly to scientific endeavors.