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.
Psychology
When experimental psychology came to Britain, Francis Galton was a leading practitioner, and, with his procedures for measuring reaction time and sensation, is considered an inventor of modern mental testing (also known as "psychometrics"). James McKeen Cattell, a student of Wundt and Galton, brought the concept to the United States, and in fact coined the term "mental test". In 1901, Cattell's student Clark Wissler published discouraging results, suggesting that mental testing of Columbia and Barnard students failed to predict their academic performance. In response to 1904 orders from the Minister of Public Instruction, French psychologists Alfred Binet and Théodore Simon elaborated a new test of intelligence in 1905–1911, using a range of questions diverse in their nature and difficulty. Binet and Simon introduced the concept of mental age and referred to the lowest scorers on their test as "idiots". Henry H. Goddard put the Binet-Simon scale to work and introduced classifications of mental level such as "imbecile" and "feebleminded". In 1916 (after Binet's death), Stanford professor Lewis M. Terman modified the Binet-Simon scale (renamed the Stanford–Binet scale) and introduced the intelligence quotient as a score report. From this test, Terman concluded that mental retardation "represents the level of intelligence which is very, very common among Spanish-Indians and Mexican families of the Southwest and also among negroes. Their dullness seems to be racial."