Who is R.M. Yerkes from The Mismeasure of Man and what is their importance?

Yerkes is the scientist who caused the army to test 1.75 million men during the First World War. He was a Harvard psychologist who wished to prove that psychology was a rigorous science. He succeeded in having the Army test its recruits and helped to devise a series of three tests of intelligence. The Army Alpha was for those who were literate. The Army Beta was for those who were illiterate or who failed the Army Alpha. An individual test was administered for those who failed the Army Beta.