Louis Leon Thurstone (May 29, 1887 – September 29, 1955) was a U.S. pioneer in psychometrics and an influential theorist of intelligence. He contributed greatly to the measurement of attitudes, and is well known for his contributions to factor analysis.
The study of intelligence has been fraught with controversy, particularly in relation to the evaluation of groups as of "higher" or "lower" intelligence than others. Thurstone's work emphasized different types of intelligence, rather than focusing on a single factor of general intelligence, and thus better recognizes the diversity of human abilities. Thustone's attitudinal scale was very influential in encouraging others, such as Guttman and Coombs, to develop practical scaling procedures in the social sciences. Thus, his work, while not providing a complete understanding of human nature, offered a number of significant advances.
Louis Leon Thurstone was born in Chicago, Illinois on May 29, 1887, to two Swedish immigrants, Conrad and Sophia Thunstrom. The family eventually changed the last name to Thurstone to avoid confusion of pronunciation and spelling. The first 14 years of Louis’s life was transient as his father changed careers several times. The career changes took the family first from Chicago to a small town in Illinois (Berwyn), then to Mississippi. From Mississippi, the family moved to Sweden where they stayed for almost six years. When he was fourteen, the family settled in Jamestown, New York State.
He later reported that moving around had a positive effect on him as he received a multicultural education. By going to different schools in different countries, he could compare the goals of education that each country offered. Through this comparison, he noticed that the heroes of the stories taught in school were always of the same nationality as the teacher. From this experience, he reflected on whether the social sciences could be and should be studied from a more objective point of view.
Young Thurstone was very adept at academics. He published for the first time at the age of sixteen in the journal Scientific America. This journal article explained how the hydroelectric plants at the Niagara Falls could be constructed so that they did not interfere with the natural beauty of the falls. His second article was published at age eighteen, again in the Scientific America. It was based on work he had done as a high school student.
Thurstone studied engineering at Cornell University beginning in 1908. Studying machine design lead Thurstone to a fascination with the human factor implied in all design. This was the beginning of his interest in psychology. Another experience encouraging his interest in psychology was working with Thomas A. Edison. Edison had heard about Thurstone inventing an innovative motion picture projector and offered him an internship.
Two of Thurstone’s biographers agreed that working with Edison was the beginning of Thurston’s interest in psychology. According to A.R. Jensen, it was at Edison laboratory that Thurstone became interested in audio perception. According to Dorothy Adkins Wood, Thurstone was very much interested in Edison’s unique problem solving ability. Did Edison’s problem solving stem from his genius or did his genius stem from his problem solving? Thurston’s interest in Psychology lead him to graduate school where he earned his Master’s degree in Psychology at age 24.
For 18 years, Thurstone worked at the Carnegie Institute of Technology in the Division of Applied Psychology. He was there at the onset of World War I. Athough he tried to enlist in the Army, he was not accepted due to a physical problem. However, he did help the Army by adapting intelligence tests to help in recruiting and training.
In 1923, Thurston went to Washington DC to work on government contracts. The year and a half was not very fruitful, but while he was there he met and married Thelma Gwinn. After accepting the Associate Professor of Psychology position at the University of Chicago, he moved with his wife to Chicago where they lived for the next 28 years. The last three years of his life were spent at the University of North Carolina Intelligence Laboratory named after him. He died in September of 1955 from heart failure.
Although Charles Spearman is credited with inventing factor analysis, Thurstone is the one who first coined the term. In addition, Thurstone is recognized as the inventor of exploratory factor analysis, a more practical variation than the confirmatory factor analysis of Spearman. The goal of Thurstone’s model is to determine the number of meaningful common factors in a correlation matrix. This produces simple structures that accounts for many of the correlations observed among the factors. Exploratory factor analysis determines the number and the nature of latent constructs within a set of observed variables. Analyzing the correlated factors can rank the factors in order of importance to the correlation. Thus, exploratory factor analysis is important tool in determining hierarchy of factors such as the contributors to intelligence.
Thurstone’s theory of intelligence centered on the existence of Primary Mental Abilities (PMA). His approach was in direct contrast with Spearman’s theory of general intelligence. Thurstone felt that differences in the results of intellectual tasks could be attributed to one or more of seven independent abilities. These seven abilities were named Space, Verbal Comprehension, Word Fluency, Number Facility, Induction, Perceptual Speed, Deduction, Rote Memory, and Arithmetic Reasoning.
The Space PMA represents the ability to recognize that two shapes are the same when one has been rotated. Perceptual Speed is the ability to recognize similarities and differences between pairs of stimuli. Verbal Comprehension involves recognizing synonyms and antonyms. Induction requires establishing a rule or pattern within a given set. Deduction involves drawing a logical inference from a set of facts or premises.
Thurstone’s theory was well supported by his early research when the subjects were University of Chicago undergraduates. It did not hold up when he tested school aged children. Apparently, the more intellectually elite subjects at the University of Chicago did not differ very much on their general intelligence. Their observable differences were noted among the PMAs. The grade school children were more diverse in their general intelligence. Therefore, the differences among their PMAs were not as notable as the differences among their general intelligence.
In psychology, the 'Thurstone scale' was the first formal technique for measuring an attitude. It was developed by Thurstone in 1928, as a means of measuring attitudes towards religion. It is made up of statements about a particular issue, and each statement has a numerical value indicating how favorable or unfavorable it is judged to be. People check each of the statements to which they agree, and a mean score is computed, indicating their attitude.
This methodological contribution of Thurstone has been noted as one of the first attempts at developing a comparative judgment scaling technique. This method of measuring attitudes on an interval scale allowed statements related to an attitude to be ranked in reference to each other. The extreme opposites of the attitude and the opinions representing the equally-distanced steps in between the opposites could be established.
This rank scale can be used to rank all possible feelings related to an issue and to categorize people expressing an opinion based on the rank of that opinion. It is used today mainly in basic research. Most researchers acknowledge that, while it is very accurate, it is too complex for applied settings.
Thurstone’s theory of intelligence was a major influence on later theories of multiple intelligences, such as those of Guilford, Gardner, and Sternberg. Guilford developed a three-dimensional model of intelligence composed of contents, operations, and processes. This model relied on the interactions of various factors similar to the interactions of the correlation of factors in Thurstone’s theory. Although Gardner’s multiple intelligences did not perfectly intersect with Thurstone’s PMAs, both theories support a practical definition of intelligence. Sternberg emphasized speed of perception and the practical application of inductive reasoning as an important part of his triarchic theory of intelligence.
Thurstone's attitudinal scale was very influential in encouraging others, such as Guttman and Coombs, to develop practical scaling procedures in the social sciences.
The early controversies raised by Thurstone lead to the effectiveness of factor analysis and, particularly multiple factor analysis, used today. His influence is seen in the development of the Minres method and Kaiser's verimax method, both founded upon multiple factor analysis.
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