Joy Paul Guilford (March 7, 1897 – November 26, 1987) was an American psychologist best remembered for his psychometric study of human intelligence, including the distinction between convergent and divergent production. Developing the views of L. L. Thurstone, Guilford rejected Charles Spearman's view that intelligence could be characterized in a single numerical parameter. He proposed that three dimensions were necessary for accurate description: operations, content, and products. A Review of General Psychology survey, published in 2002, ranked Guilford as the 27th most cited psychologist of the 20th century. Career Guilford graduated from the University of Nebraska before studying under Edward Titchener at Cornell. Guilford was elected a member of the Society of Experimental Psychologists in 1937, and in 1938 he became the third president of the Psychometric Society, following in the footsteps of its founder Louis Leon Thurstone and of Edward Thorndike, who held the position in 1937. Guilford held a number of posts at Nebraska and briefly at the University of Southern California. In 1941 he entered the U.S. Army as a Lieutenant Colonel and served as Director of Psychological Research Unit No. 3 at Santa Ana Army Air Base. There he worked on the selection and ranking of aircrew trainees as the Army Air Force investigated why a sizable proportion of trainees were not graduating. Promoted to Chief of the Psychological Research Unit at the U.S. Army Air Forces Training Command Headquarters in Fort Worth, Guilford oversaw the Stanine (Standard Nine) Project in 1943, which identified nine specific intellectual abilities crucial to flying a plane. (Stanines, now a common term in educational psychology, was coined during Guilford's project). Over the course of World War II, Guilford's use of these factors in the development of the two-day Classification Test Battery was significant in increasing graduation rates for aircrew trainees. Discharged as a full colonel after the war, Guilford joined the Education faculty at the University of Southern California and continued to research the factors of intelligence. He published widely on what he ultimately named the Structure of Intellect theory, and his post-War research identified a total of 90 discrete intellectual abilities and 30 behavioral abilities. Guilford's 20 years of research at Southern California were funded by the National Science Foundation, the Office of Education of the former Health, Education and Welfare Department, and the Office of Naval Research. Although Guilford's subjects were recruits at the Air Force Training Command