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

. He conceived the approach to measurement known as the law of comparative judgment, and is well known for his contributions to factor analysis. A '' Review of General Psychology'' survey, published in 2002, ranked Thurstone as the 88th most cited psychologist of the 20th century, tied with

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James J. Gibson James Jerome Gibson (; January 27, 1904 – December 11, 1979) was an American psychologist and is considered to be one of the most important contributors to the field of visual perception. Gibson challenged the idea that the nervous system ...

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, to Swedish immigrant parents. Thurstone originally received a master's degree in mechanical engineering from Cornell University in 1912. Thurstone was offered a brief assistantship in the laboratory of Thomas Edison. In 1914, after two years as an instructor of geometry and drafting at the University of Minnesota, he enrolled as a graduate student in psychology at the University of Chicago (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 and ...

, who co-discovered the structure of DNA. 1952, he established the

L. L. Thurstone Psychometric Laboratory L. L. Thurstone Psychometric Laboratory is a psychometrics and quantitative psychology laboratory housed within the Department of Psychology and Neuroscience at University of North Carolina at Chapel Hill. It was founded by Louis Leon Thurstone i ...

at the University of North Carolina at

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 neighbo ...

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, while ...

of IQ scores used today, as opposed to the Intelligence Test system originally used by Alfred Binet. He is also known for the development of the

Thurstone scale Louis Leon Thurstone (29 May 1887 – 29 September 1955) was an American pioneer in the fields of psychometrics and psychophysics. He conceived the approach to measurement known as the law of comparative judgment, and is well known for his cont ...

. 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 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 c ...

and JP Guilford, founded the journal '' Psychometrika'' 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 law of comparative judgment. 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 Comparison or comparing is the act of evaluating two or more things by determining the relevant, comparable characteristics of each thing, and then determining which characteristics of each are similar to the other, which are different, and t ...

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 (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 (1949); Centennial Award, Northwestern University (1951); Honorary Doctorate, University of Göteborg (1954). Thurstone was President of American Psychological Association (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 ''The Vectors of Mind'' is a book published by American psychologist Louis Leon Thurstone in 1935 that summarized Thurstone's methodology for multiple factor analysis. Overview ''The Vectors of Mind'' presents Thurstone's methods for conductin ...

'' (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

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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