Louis Leon Thurstone (29 May 1887 – 29 September 1955) was an American pioneer in the fields of

psychometrics Psychometrics is a field of study within psychology concerned with the theory and technique of measurement. Psychometrics generally refers to specialized fields within psychology and education devoted to testing, measurement, assessment, and ...

and

psychophysics Psychophysics quantitatively investigates the relationship between physical stimuli and the sensations and perceptions they produce. Psychophysics has been described as "the scientific study of the relation between stimulus and sensation" or, ...

. He conceived the approach to measurement known as the

law of comparative judgment The law of comparative judgment was conceived by L. L. Thurstone. In modern-day terminology, it is more aptly described as a model that is used to obtain measurements from any process of pairwise comparison. Examples of such processes are the compa ...

, and is well known for his contributions to

factor analysis Factor analysis is a statistical method used to describe variability among observed, correlated variables in terms of a potentially lower number of unobserved variables called factors. For example, it is possible that variations in six observed ...

. A ''

Review of General Psychology ''Review of General Psychology'' is the quarterly scientific journal of the American Psychological Association Division 1: The Society for General Psychology. The journal publishes cross-disciplinary psychological articles that are conceptual, the ...

'' survey, published in 2002, ranked Thurstone as the 88th most cited psychologist of the 20th century, tied with John Garcia, James J. Gibson,

David Rumelhart David Everett Rumelhart (June 12, 1942 – March 13, 2011) was an American psychologist who made many contributions to the formal analysis of human cognition, working primarily within the frameworks of mathematical psychology, symbolic artif ...

, Margaret Floy Washburn, and

Robert S. Woodworth Robert Sessions Woodworth (October 17, 1869 – July 4, 1962) was an American academic psychologist and the creator of the personality test which bears his name. A graduate of Harvard and Columbia, he studied under William James along with othe ...

Background and history

Louis Leon Thurstone was born in

Chicago, Illinois (''City in a Garden''); I Will , image_map = , map_caption = Interactive Map of Chicago , coordinates = , coordinates_footnotes = , subdivision_type = Country , subdivision_name ...

, to Swedish immigrant parents. Thurstone originally received a master's degree in

mechanical engineering Mechanical engineering is the study of physical machines that may involve force and movement. It is an engineering branch that combines engineering physics and mathematics principles with materials science, to design, analyze, manufacture, ...

from

Cornell University Cornell University is a private statutory land-grant research university based in Ithaca, New York. It is a member of the Ivy League. Founded in 1865 by Ezra Cornell and Andrew Dickson White, Cornell was founded with the intention to tea ...

in 1912. Thurstone was offered a brief assistantship in the laboratory of

Thomas Edison Thomas Alva Edison (February 11, 1847October 18, 1931) was an American inventor and businessman. He developed many devices in fields such as electric power generation, mass communication, sound recording, and motion pictures. These inventi ...

. In 1914, after two years as an instructor of geometry and drafting at the

University of Minnesota The University of Minnesota, formally the University of Minnesota, Twin Cities, (UMN Twin Cities, the U of M, or Minnesota) is a public land-grant research university in the Twin Cities of Minneapolis and Saint Paul, Minnesota, United States. ...

, he enrolled as a graduate student in psychology at the

University of Chicago The University of Chicago (UChicago, Chicago, U of C, or UChi) is a private research university in Chicago, Illinois. Its main campus is located in Chicago's Hyde Park neighborhood. The University of Chicago is consistently ranked among the b ...

(PhD, 1917). He later returned to the University of Chicago (1924–1952) where he taught and conducted research; among his students was

James Watson James Dewey Watson (born April 6, 1928) is an American molecular biologist, geneticist, and zoologist. In 1953, he co-authored with Francis Crick the academic paper proposing the double helix structure of the DNA molecule. Watson, Crick a ...

, who co-discovered the structure of DNA. 1952, he established the L. L. Thurstone Psychometric Laboratory at the

University of North Carolina The University of North Carolina is the multi-campus public university system for the state of North Carolina. Overseeing the state's 16 public universities and the NC School of Science and Mathematics, it is commonly referred to as the UNC S ...

Chapel Hill Chapel Hill or Chapelhill may refer to: Places Antarctica * Chapel Hill (Antarctica) Australia *Chapel Hill, Queensland, a suburb of Brisbane *Chapel Hill, South Australia, in the Mount Barker council area Canada *Chapel Hill, Ottawa, a neighbou ...

Factor analysis and work on intelligence

Thurstone was responsible for the standardized mean and

standard deviation In statistics, the standard deviation is a measure of the amount of variation or dispersion of a set of values. A low standard deviation indicates that the values tend to be close to the mean (also called the expected value) of the set, whil ...

of IQ scores used today, as opposed to the

Intelligence Test An intelligence quotient (IQ) is a total score derived from a set of standardized tests or subtests designed to assess human intelligence. The abbreviation "IQ" was coined by the psychologist William Stern for the German term ''Intelligenzqu ...

system originally used by

Alfred Binet Alfred Binet (; 8 July 1857 – 18 October 1911), born Alfredo Binetti, was a French psychologist who invented the first practical IQ test, the Binet–Simon test. In 1904, the French Ministry of Education asked psychologist Alfred Binet to ...

. He is also known for the development of the Thurstone scale. Thurstone's work in factor analysis led him to formulate a model of intelligence centered on "Primary Mental Abilities" (PMAs), which were independent group factors of intelligence that different individuals possessed in varying degrees. He opposed the notion of a singular

general intelligence The ''g'' factor (also known as general intelligence, general mental ability or general intelligence factor) is a construct developed in psychometric investigations of cognitive abilities and human intelligence. It is a variable that summarizes ...

that factored into the scores of all psychometric tests and was expressed as a

mental age Mental age is a concept related to intelligence. It looks at how a specific individual, at a specific age, performs intellectually, compared to average intellectual performance for that individual's actual chronological age (i.e. time elapsed sin ...

. In 1935 Thurstone, together with

EL Thorndike Edward Lee Thorndike (August 31, 1874 – August 9, 1949) was an American psychologist who spent nearly his entire career at Teachers College, Columbia University. His work on comparative psychology and the learning process led to the theory of ...

and JP Guilford, founded the journal ''

Psychometrika ''Psychometrika'' is the official journal of the Psychometric Society, a professional body devoted to psychometrics and quantitative psychology. The journal covers quantitative methods for measurement and evaluation of human behavior, including ...

'' and also the Psychometric Society, going on to become the society's first president in 1936. Thurstone's contributions to methods of factor analysis have proved valuable in establishing and verifying later psychometric factor structures, and have influenced the hierarchical models of intelligence in use in intelligence tests such as WAIS and the modern Stanford-Binet IQ test. The seven primary mental abilities in Thurstone's model were ''verbal comprehension'', ''word fluency'', ''number facility'', ''spatial visualization'', ''associative memory'', ''perceptual speed'', and ''reasoning''.

Contributions to measurement

Despite his contributions to factor analysis, Thurstone (1959, p. 267) cautioned: "When a problem is so involved that no rational formulation is available, then some quantification is still possible by the coefficients of correlation of contingency and the like. But such statistical procedures constitute an acknowledgement of failure to rationalize the problem and to establish functions that underlie the data. We want to measure the separation between the two opinions on the attitude continuum and we want to test the validity of the assumed continuum by means of its internal consistency". Thurstone's approach to measurement was termed the

. He applied the approach in

, and later to the

measurement Measurement is the quantification of attributes of an object or event, which can be used to compare with other objects or events. In other words, measurement is a process of determining how large or small a physical quantity is as compared ...

of psychological values. The so-called 'Law', which can be regarded as a measurement model, involves subjects making a comparison between each of a number of pairs of stimuli with respect to magnitude of a property, attribute, or attitude. Methods based on the approach to measurement can be used to estimate such scale values. Thurstone's Law of comparative judgment has important links to modern approaches to social and psychological measurement. In particular, the approach bears a close conceptual relation to the

Rasch model The Rasch model, named after Georg Rasch, is a psychometric model for analyzing categorical data, such as answers to questions on a reading assessment or questionnaire responses, as a function of the trade-off between the respondent's abilities, ...

(Andrich, 1978), although Thurstone typically employed the

normal distribution In statistics, a normal distribution or Gaussian distribution is a type of continuous probability distribution for a real-valued random variable. The general form of its probability density function is : f(x) = \frac e^ The parameter \mu ...

in applications of the Law of comparative judgment whereas the Rasch model is a simple

logistic function A logistic function or logistic curve is a common S-shaped curve (sigmoid curve) with equation f(x) = \frac, where For values of x in the domain of real numbers from -\infty to +\infty, the S-curve shown on the right is obtained, with the ...

. Thurstone anticipated a key

epistemological Epistemology (; ), or the theory of knowledge, is the branch of philosophy concerned with knowledge. Epistemology is considered a major subfield of philosophy, along with other major subfields such as ethics, logic, and metaphysics. Episte ...

requirement of measurement later articulated by Rasch, which is that relative scale locations must 'transcend' the group measured; i.e. scale locations must be invariant to (or independent of) the particular group of persons instrumental to comparisons between the stimuli. Thurstone (1929) also articulated what he referred to as the ''additivity criterion'' for scale differences, a criterion which must be satisfied in order to obtain interval-level measurements.

Awards and honors

Thurstone received numerous awards, including: Best Article,

American Psychological Association The American Psychological Association (APA) is the largest scientific and professional organization of psychologists in the United States, with over 133,000 members, including scientists, educators, clinicians, consultants, and students. It ha ...

(1949); Centennial Award,

Northwestern University Northwestern University is a private research university in Evanston, Illinois. Founded in 1851, Northwestern is the oldest chartered university in Illinois and is ranked among the most prestigious academic institutions in the world. Charte ...

(1951); Honorary Doctorate,

University of Göteborg The University of Gothenburg ( sv, Göteborgs universitet) is a university in Sweden's second largest city, Gothenburg. Founded in 1891, the university is the third-oldest of the current Swedish universities and with 37,000 students and 6000 st ...

(1954). Thurstone was President of

(1933) and first President of the American Psychometric Society (1936). ''L.L. Thurstone'' (Human Intelligence)
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Selected works

* ''The Nature of Intelligence'' (London: Routledge. 1924) * ''The Effect of Motion Pictures on the Social Attitudes of High School Children'' Ruth C. Peterson & L.L. Thurstone, MacMillan, 1932 * ''Motion Pictures and the Social Attitudes of Children'' Ruth C. Peterson & L.L. Thurstone, MacMillan, 1933 *''The Vectors of Mind. Address of the president before the American Psychological Association, Chicago meeting, September, 1933'' ( Psychological Review, 41, 1–32. 1934) * '' The Vectors of Mind'' (Chicago, IL, US: University of Chicago Press 1935) *''Primary mental abilities'' (Chicago: University of Chicago Press. 1938) * ''Multiple-Factor Analysis'' (Chicago: University of Chicago Press. 1947) * ''The Fundamentals of Statistics'' (MacMillan: Norwood Press. 1925)

References

Sources

* * * * * * * * *

External links

The Vectors of Mind 1934

{{DEFAULTSORT:Thurstone, Louis Leon Cornell University College of Engineering alumni University of Chicago alumni Intelligence researchers Fellows of the American Statistical Association American people of Swedish descent 1887 births 1955 deaths Presidents of the American Psychological Association