Joy Paul Guilford (March 7, 1897 – November 26, 1987) was an American psychologist best known for his psychometric study of human intelligence, including the distinction between convergent and divergent production.
[3] 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.
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.
Guilford's post-war research led to the development of classification testing that, modified in different ways, entered into the various personnel assessments administered by all branches of the U.S. Armed Services.
Each ability stands for a particular operation in a particular content area and results in a specific product, such as Comprehension of Figural Units or Evaluation of Semantic Implications.
According to Jensen (1998), Guilford's contention that a g-factor was untenable was influenced by his observation that cognitive tests of U.S. Air Force personnel did not show correlations significantly different from zero.