Cattell was the first professor of psychology in the world (University of Pennsylvania, 1887)!

He started as a 'literature major' and drifted to philosophy in Europe, studying under Wundt. This led to a subsequent appointment as a fellow at John Hopkins where he worked with Dewey, Jastrow, Pierce, and Hall -- all founders of modern psychology. Cattell was acquainted with Galton who inspired him to formally investigate individual differences.

His major contribution to psychology was the realization of the importance, and subsequent implementation, of quantitative methodologies and techniques. This application ultimately changed the course of the discipline. One may thank Cattell for the term "mental test" which he introduced to the world in 1890. How strange that only 100 years ago this construct did not (formally) exist!