Joy Paul Guilford (March 7, 1897, Marquette, Nebraska – November 26, 1987, Los Angeles ) 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 LL Thurstone , Guilford rejected Charles Spearman ‘s view of intelligence in a single numerical parameter. He proposed that three dimensions were necessary for an accurate description: operations, content, and products. A Review of General Psychology , published in 2002, ranked Guilford as the 27th most cited psychologist of the 20th century. 
Guilford graduated from the University of Nebraska before studying under Edward Titchener at Cornell . In 1938 Guilford became the third president of the Psychometric Society, following in the footsteps of the founder Louis Leon Thurstone and 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 US 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 aircrew and 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 US Army Air Force Training Command Headquarters in Fort Worth, Guilford oversaw the Stanine (Standard Nine) Project in 1943, which identified specific capabilities of flying. ( 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 of battery was significant in increasing graduation rates for aircrew trainees.
Disciplined 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 the subject of the structure of intellectual 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, the Health Training, Education and Welfare Department, and the Office of Naval Research. Although Guilford’s subjects were recruited at the Air Force Training Command at Randolph Air Force Base in San Antonio, the Naval Research Office managed this research.
Guilford’s post-war research, which has been modified in various ways, has entered into the various personal accounts administered by all branches of the US Armed Services. The United States Military Qualifying Examinations of the 1950s, 1960s, and 1970s descended from Guilford’s research.
Structure of Intellect theory
According to Guilford’s Structure of Intellect (SI) theory (1955), an individual’s performance can be traced back to the underlying mental abilities or factors of intelligence. SI theory understood up to 180 different intellectual abilities organized along three dimensions: operations, content, and products.
The Structure of Intellect Advanced Theory by Guilford was applied by Mary N. Meeker for educational purposes.
SI includes six operations or general intellectual processes:
- Cognition – The ability to understand, understand, discover, and become aware of information
- Memory recording – The ability to encode information
- Memory retention – The ability to recall information
- Divergent production – The ability to generate multiple solutions to a problem; creativity
- Convergent production – The ability to deduce a single solution to a problem; rule-following or problem-solving
- Evaluation – The ability to judge or not is accurate, consistent, or valid
SI includes four broad areas of information to which the human intellect applies the six operations:
- Figural – Concrete, real world information, tangible objects, things in the environment – It includes A. visual: information perceived through sight, B. auditory: information perceived through hearing, and C. kinesthetic : information perceived through one’s own physical actions
- Symbolic – Information perceived as symbols or signs that stand for something else, eg, Arabic numerals, the letters of an alphabet, or musical and scientific notation
- Semantic – Concerned with verbal meaning and ideas – Generally considered to be abstract in nature.
- Behavioral – Information perceived as acts of people (This dimension is not fully researched in Guilford’s project.
As the name suggests, this dimension contains results of applying specific operations to specific contents. The SI model includes six products in increasing complexity:
- Units – Single items of knowledge
- Classes – Sets of units sharing common attributes
- Relationships – Units linked as opposites or in associations, sequences, or analogies
- Systems – Multiple relationships interrelated to understood structures or networks
- Transformations – Changes, perspectives, conversions, or mutations to knowledge
- Implications – Predictions , inferences , consequences, or anticipations of knowledge
Therefore, according to Guilford there are 5 x 6 x 6 = 180 intellectual abilities or factors (so it is not included in the model). Such ability for a particular operation in a specific area and results in a specific product, such as Comprehension of Figural Units or Evaluation of Semantic Implications.
Guilford ‘s original model was made up of 120 components (not included in the results of this study). When he has been published, his model has been increased to 5 x 5 x 6 = 150 categories. When Guilford separated the memory functions, his model finally increased to 180 factors. 
Various researchers have criticized the statistical techniques used by Guilford. Selon Jensen (1998), Guilford’s contention That has g -factor Was untenable Was Influenced By His observation tests of cognitive That USAF staff Did not show correlations Significantly different from zero. According to one reanalysis, this result from artifacts and methodological errors. Applying more robust methodologies, the correlations in Guilford’s data sets are positive.  In another reanalysis, randomly generated models were found to be supported by Guilford’s own theory. 
Guilford’s Structure of Intellect. Carroll (1993) summarized the view of later researchers: 
- “Guilford’s SOI model must, therefore, be marked down to a somewhat eccentric aberration in the history of intelligence models. that the model is valid and widely accepted, when clearly it is not. “
- Guilford, JP (1939) General psychology. New York, NY: Van Nostrand Company, Inc.
- Guilford, JP (1950) Creativity, American Psychologist , Volume 5, Issue 9, 444-454.
- Guilford, JP (1967). The Nature of Human Intelligence .
- Guilford, JP & Hoepfner, R. (1971). The Analysis of Intelligence .
- Guilford, JP (1982). Cognitive psychology’s ambiguities: Some suggested remedies. Psychological Review, 89, 48-59.
- Jump up^ Haggbloom, Steven J .; Warnick, Jason E .; Jones, Vinessa K .; Yarbrough, Gary L .; Russell, Tenea M .; Borecky, Chris M .; McGahhey, Reagan; et al. (2002). “The most eminent psychologists of the 20th century” . Review of General Psychology . 6 (2): 139-152. doi : 10.1037 / 1089-26126.96.36.199 .
- Jump up^ Guilford, JP (1988). Some changes in the structure of intellect model. Educational and Psychological Measurement, 48,1-4.
- Jump up^ Jensen 1998, 115-117.
- Jump up^ Mackintosh 1998, 214-215.
- Jump up^ Carroll 1993, 60. For a more detailed review of the Structure-of-Intellect model, see 57-60.
- Barberpole illusion
- Carroll, JB (1993). Human Cognitive Abilities . Cambridge, UK: Cambridge University Press.
- Jensen, AR (1998). The g Factor: The Science of Mental Ability . Westport, CT: Praeger.
- Mackintosh, NJ (1998). IQ and Human Intelligence. Oxford, UK: Oxford University Press.