Mental testing was invented in the 19th century partially as a reaction to the development of universal and compulsory primary education, which required the assessment of children’s cognitive abilities. Sir Francis Galton was an English scientist who was highly interested in measuring human intelligence. Galton invented the correlation coefficient and found a strong correlation in the children’s examination grades, which led him to theorize about intelligence as a single mental ability (Leahey, 2018). Although Galton’s tests were a failure by today’s measure, he was the first to introduce the fee-for-service model and was the father of mental testing, which his followers later improved. In contrast to Galton, French psychologist Alfred Binet focused his efforts on studying high-level cognitive skills. Binet’s practical tests, which were developed initially to differentiate between normal and subnormal children, proved to be more effective and useful than Galton’s. Mental testing “was the founding cornerstone of applied psychology” (Leahey, 2018, p. 208), which has built bridges between psychology and other disciplines. Nowadays, intelligence tests are widely used in education and hiring.
Leahey, T.H. (2018). A history of psychology: From antiquity to modernity (8th ed.). Routledge.