Charles Spearman

Charles Spearman (1863-1945) was an English Psychologist, studied with Wundt, teaches Cattell and Wechsler and influenced many of the modern exponents of Psychology. Invented statistical technique known as factor analysis, his research preceded many of our actual testing ideas.

Student of: Wundt
Influenced by: Galton
Students: R. B. Cattell, Wechsler
Influenced: Anastasi, Guilford, Vernon, Burt, Detterman
Time Period: The Great Schools' Influence

Education:
Studied engineering in college
University of Leipzig , Ph.D. in experimental psychology (under Wilhelm Wundt) (1906)

Career:
Published “General Intelligence’ Objectively Determined and Measured” (1904)
University College, London, Reader in Experimental Psychology (1907-1911); Grote Professor of Mind and Logic (successor to William McDougal) (1911-1928); Professor of Psychology (1928-1932) (Succeeded by Cyril Burt)
Numerous honors and awards, including: Fellow of the Royal Society ( Great Britain) and member of the National Academy of Sciences ( U.S.A.)

Major Contributions:
“First systematic psychometrician” and father of classical test theory (Jensen, 1994)
Pioneer of the statistical technique called factor analysis
Discovered a general factor (g) in correlations among mental tests
Definition of Intelligence

“As regards the delicate matter of estimating ‘Intelligence,’ the guiding principle has been not to make any a priori assumptions as to what kind of mental activity may be thus termed with greatest propriety. Provisionally, at any rate, the aim was empirically to examine all the various abilities having any prima facie claims to such title, ascertaining their relations to one another and to other functions (Spearman, 1904, p. 249-250).”

Ideas and Interests
Charles Spearman started his psychology career relatively late in life, beginning his Ph.D. studies at age 34 and accepting his first university position at age 42. Yet, his technical and theoretical contributions to the development of intelligence research as a scientific enterprise cannot be overstated. He was the first to offer a tenable psychometric definition of intelligence, and is therefore considered to be the father of classical test theory (Jensen, 1994). In a famous article, “General Intelligence’ Objectively Determined and Measured” (1904), Spearman proposed the idea that intelligent behavior is generated by a single, unitary quality within the human mind or brain. Spearman derived this theoretical entity, called the general factor, or simply g, through a new statistical technique that analyzed the correlations among a set of variables. This technique, called factor analysis, demonstrated that scores on all mental tests are positively correlated; this offered compelling evidence that all intelligent behavior is derived from one metaphorical pool of mental energy. Although proponents of multiple intelligence theory reject this interpretation, factor analysis remains one of the most important tools in 21 st century intelligence research. Like his predecessors James McKeen Cattell and Francis Galton, Spearman had been a student in William Wundt’s experimental psychology laboratory, and like Cattell and Galton, he found the idea of a single, biologically-based source of human intelligence appealing. However, earlier researchers had failed to discover any statistically meaningful relationships between mental tests; since the tests did not correlate with one another, it appeared that they could not be measuring the same thing; that is, they could not all be measuring “intelligence.” (See the Wissler Controversy Hot Topic). Spearman was able to demonstrate that uncorrected correlation coefficients will always underestimate the true degree of the relationships among any set of variables, and that this underestimation is particularly severe when the scores on the tests have a restricted range of values, as was the case with Cattell’s anthropometric tests. Spearman derived a statistical formula to correct for this underestimation. When he applied his corrective procedure to Cattell’s data, he found substantial positive correlations among all the variables measured by the mental tests, and also between the mental tests and other variables that could be considered measures of mental ability. Through an extended formula, he was able to demonstrate that a common source of variance accounted for the correlations among all the mental tests, and he called this the general factor, or g. This finding reinvigorated the idea that intelligent behavior arises from a single metaphorical entity, and it forms the foundation for many present-day theories of human intelligence (Jensen, 1994).

Selected Publications:

Spearman, C. (1904). "General intelligence," objectively determined and measured. American Journal of Psychology, 15, 201-293.

Spearman, C. (1923). The nature of ‘intelligence’ and the principles of cognition (2 nd ed.). London: Macmillan.

Spearman, C. (1927). The abilities of man. London: Macmillan.

Spearman, C. (1930). Autobiography. In C. Murchison (Ed.), A history of psychology in autobiography (Vol. 1, pp. 199-333). Worcester, MA: Clark University Press.

Spearman, C., & Jones, L. W. (1950). Human ability. London: Macmillan.

References:

Jensen, A. R. (1994). Spearman, Charles Edward. In R. J. Sternberg (Ed.), Encyclopedia of intelligence (Vol. 1, pp. 1007-1014). New York: Macmillan.

Spearman, C. (1904). "General intelligence," objectively determined and measured. American Journal of Psychology, 15, 201-293.

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The Wissler Controversy

And don't we all like a bit of scandal? What was this about?

Clark Wissler (1870-1947) is best known today as an influential American anthropologist, but his early training was in psychology. His 1901 doctoral dissertation created an academic uproar by purportedly debunking some of the most influential intelligence theories of the time. The controversy was made scandalous by the fact that Wissler's findings discredited the research of his mentor, James McKeen Cattell. (Fancher, 1985, p. 48-49)  To appreciate the iconoclastic nature of the Wissler controversy, it is necessary to understand the importance of the research of two notable men who proceeded him: Francis Galton and James McKeen Cattell. Francis Galton (1822-1911) was a believer in the hereditary basis of intelligence, and is credited with popularizing the phrase "nature and nurture." He originated and named the eugenics movement, in service of which he created the basic idea of the intelligence test. (It is important to note however, that the term "intelligence test" did not come into being until later.) (Fancher, 1985) Galton believed that intelligence was a matter of neurological efficiency. Therefore, he theorized that it could be tested by measuring reaction time and sensory acuity. In the mid 1880s he established an anthropometric laboratory at London's South Kensington Museum, cleverly enticing visitors to spend three pence apiece to enjoy the novelty of undergoing a variety of psychophysical tests. Besides providing amusement for the museum's patrons, this unusual laboratory provided a vast amount of research data. (Fancher, 1985, pp. 36-37; Sternberg, 1990, p. 70-71) At about the same time, an American doctoral student, James McKeen Cattell (1860-1944) was conducting a series of reaction time experiments in Germany. When he became aware of Galton's anthropometric laboratory, he began to correspond with him, and designed a series of 50 psychophysical tests based on Galton's earlier work. He established his own anthropometric laboratory at Cambridge University, and became a successful international advocate of the psychophysical approach to mental testing. (Fancher, 1985, pp. 45-47) The work of these two men was of pivotal importance to the field of experimental psychology. Psychophysical testing had great popular appeal, and was being enthusiastically embraced by researchers from many different countries. (Fancher, 1985, pp. 47-48)

Wissler's Dissertation
 It is rare for a graduate student to single-handedly crush the morale of the professional establishment, but that is exactly what Clark Wissler did. At the time of his doctoral dissertation, Wissler was one of Cattell's graduate students at Columbia University. He obtained the psychophysical test scores from several hundred Columbia University and Barnard College students who had been Cattell's research subjects. He then used the newly perfected Pearson correlation coefficient to examine the relationship between each student's score on each of the tests and their undergraduate academic grades. The surprising result was that there was virtually no correlation between scores on Cattell's tests and academic achievement. Perhaps equally surprising was the fact that scores on Cattell's tests did not even appear to correlate with each other. Since the tests didn't agree among themselves, and they didn't correlate with independent measures of mental ability (undergraduate academic grades), it did not seem possible that they could be valid measures of intelligence. (Fancher, 1985, pp. 48-49; Sternberg, 1990, pp. 72-73)


Impact of Wissler's Dissertation
At the time of Wissler's dissertation, psychophysical measurement was the primary research paradigm for intelligence testing. The eugenics movement was gaining momentum, and the majority of the psychological community was thoroughly invested in the findings of Galton and Cattell. After Wissler's results became known, psychology gradually lost interest in psychophysical testing. Although Cattell remained a psychologist, he also became disenchanted with psychophysical testing, and spent the remainder of his career in relative obscurity. (Fancher, 1985, p. 49) Galton continued to be interested in eugenics and hereditary theory until he died in 1911. (Fancher, 1985, p. 82) Many critics have pointed out that Wissler's research was flawed. When Charles Spearman first heard of the dissertation, he was disheartened. However, he soon realized that there was a degree of unreliability in Cattell's sensory discrimination scores. Therefore, Wissler's correlation coefficients would have underestimated the degree of the relationships between variables. Spearman believed that applying a correction formula to the original data would allow the true degree of relationships to be assessed. (Fancher, 1985, pp. 88-89)  Other critics have argued that even if Wissler's correlations were correct, the inferences based on his results were not. Wissler's research subjects were members of a very homogeneous group, i.e., undergraduate students from prestigious universities. Since these students were relatively similar to one another, correlations would be expected to be lower than those obtained from a more heterogeneous group. (Sternberg, 1990, pp. 73-74)

Later Career of Wissler
Almost immediately after his iconoclastic upheaval (and perhaps in part because of it) Wissler abruptly changed fields. (Fancher, 1985, pp. 48-49) Although he always maintained an avuncular interest in psychology, most of what is written about him today refers to his long and prolific career in anthropology. In 1902 he became an assistant in Ethnology at the American Museum of Natural History in New York--a position that eventually spawned his appointment as Curator. During this period he became enthusiastically involved in anthropological fieldwork, focusing his energies on the culture and customs of Native Americans. He lectured at Columbia and Yale, wrote dozens of books and articles, and contributed a sizable amount of ethnographic data to the field of anthropology. (Freed & Freed, 1993) Although Clark Wissler left the field of psychology behind a century ago, psychology has not left him behind. His doctoral dissertation permanently changed the dominant research paradigm for intelligence testing. (Fancher, 1985, p. 49) Although advances in neurophysiology may eventually impact intelligence testing, anthropometric testing (as it was conceived by Galton, Cattell, Wissler and others) is rarely used today.


References

Fancher, R.E. (1985). The intelligence men: Makers of the IQ controversy. New York: W.W. Norton & Company.

Freed, S.A., & Freed, R.S. (1992). Clark Wissler. In P.H. Raven (Ed.), National Academy of Sciences of the United States of America Biographical Memoirs, 61, 468-497. Washington D.C.: National Academy Press.

Sternberg, R.J. (1990). Metaphors of mind: Conceptions of the nature of intelligence. Cambridge: Cambridge University Press.

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Wilhelm Wundt

Wilhelm Wundt  (1832-1920) is an German Philosopher & Psychologist

Students: J. M. Cattell, Titchener, Spearman
Time Period: The Great Schools

Education:
Tubingen University (1851)
University of Heidelberg (M.D., 1856)

Career:
Privatdozent in the Physiological (1857-1864)
Professor of Inductive Philosophy at Zurich University (1874)
Professor of Inductive Philosophy at Leipzig University (1875-1917)
Established the world's first experimental laboratory in psychology, the Institut fur Experimentelle Psychologie (1879)

Major Contributions
Often referred to as the "Father of Experimental Psychology" and the "Founder of Modern Psychology"

Ideas and Interests
Wundt established the first laboratory in the world dedicated to experimental psychology. This laboratory became a focus for those with a serious interest in psychology, first for German philosophers and psychology students, then for American and British students as well. All subsequent psychological laboratories were closely modeled in their early years on the Wundt model. Wundt's revolutionary approach to psychological experimentation moved psychological study from the domain of philosophy and the natural sciences and began to utilize physiological experimental techniques in the laboratory. To Wundt, the essence of all total adjustments of the organism was a psychophysical process, an organic response mediated by both the physiological and the psychological. He pioneered the concept of stating mental events in relation to objectively knowable and measurable stimuli and reactions. Wundt perceived psychology as part of an elaborate philosophy where mind is seen as an activity, not a substance. The basic mental activity was designated by Wundt as 'apperception'. Physiological psychology was concerned with the process of excitations from stimulation of the sense organs, through sensory neurons to the lower and higher brain centers, and from these centers to the muscles. Parallel with this process ran the events of mental life, known through introspection. Introspection became, for Wundt, the primary tool of experimental psychology. In Wundt's 1893 edition of Physiological Psychology, he published the 'tridimensional theory of feeling': feelings were classified as pleasant or unpleasant, tense or relaxed, excited or depressed. A given feeling might be at the same time a combination of one of each of the categories. Wundt's method of introspection did not remain a fundamental tool of psychological experimentation past the early 1920's. His greatest contribution was to show that psychology could be a valid experimental science. His influence in promoting psychology as a science was enormous. Despite poor eyesight, Wundt, it has been estimated, published 53,000 pages, enough to stock a complete library. As noted above, a primary preoccupation of many early psychologists, such as Wundt and Fechner, was with the measurement of powers of sensory discrimination, resulting in the theory and methodology of psychophysics, the science of quantitative relations between physical magnitudes and sensations. This interest with measurements led Wundt to develop what would be the foundation for Binet's scale of intelligence. Binet had developed a scale where specific tasks were directly correlated to different levels of abilities or a mental age. However, Binet was not suggesting that each task would correspond exactly and reliably to a particular mental level. As the scale developed, Binet found it necessary to use a number of tasks at each level to determine mental age. At this point, the task of determining a person's mental age was reminiscent of one of the psychophysical methods developed by Wundt to determine the level of a person's sensitivity to faint stimuli or to small physical differences in stimuli.

Publications
Vorlesungen uber die Menschen und Tier-Seele (1863, English translation, Lectures on Human and Animal Psychology, 1896)
Grundzuge der physiologeschen Psychologie (1874, English translation, Principles of Physiological Psychology, 1904).
Philosophische Studien, the first journal of psychology (1871)
Volkerpsychologie (social psychology), (10 vols, 1911-1920)

James McKeen Cattell

James McKeen Cattell (1860-1944) was an Psychologist, Publisher, and Editor

Student of: Galton, Wundt, Hall
Influenced: E. L. Thorndike, H. L. Hollingworth, P. Cattell, Wissler
Time Period: The Great Schools

Education:
Lafayette, BA in 1880 & MA in 1883.
Studied in Europe with Wundt in Leipzig and Lotze at Gottingen 1880.
Johns Hopkins University, 1882-1883
Leipzig as Wundt's assistant, Ph.D. in 1886

Career:
Researcher and Lecturer in Experimental Psychology, St. John's College, Cambridge
Lecturer in Psychology, Bryn Mawr, 1887
Professor of Psychology, University of Pennsylvania, 1888
Department Head of Psychology, Anthropology, and Philosophy, Columbia University, 1891-1905
President of the American Psychological Association, 1895
Presider, Ninth International Congress of Psychology, New Haven, Connecticut, 1929

Major Contributions
James McKeen Cattell is an important figure in psychology and the study of human intelligence for several reasons. While at Leipzig, working under Wundt, he was the first American to publish a dissertation, Psychometric Investigation. After his return from Europe, perhaps no other person contributed more to the strengthening of American psychology in the late 1890s and early 1900s. He was involved with the formation of many major publications, including co-founder and co-editor of The Psychological Review (1894-1903), editor and publisher of the Journal of Science (1894-1944 ), founder of the Psychological Corporation (1921), and founder of the Science Press (1923), among many others. He was similarly involved with major professional organizations, including the American Psychological Association, the American Association of University Professors, and the American Association for the Advancement of Science. One of Cattell's goals was to have psychology viewed as a science on par with the physical and life sciences. As he noted in his presidential address to the American Psychological Association, In the struggle for existence that obtains among the sciences psychology is continually gaining ground.... The academic growth of psychology in American during the past few years is almost without precedent.... Psychology is a required subject in the undergraduate curriculum ..., and among university courses psychology now rivals the other leading sciences in the number of students attracted and in the amount of original work accomplished. (1896, p. 1). In that address, Cattell provides additional evidence of the growth of psychology as a science, including a favorable comparison of the major academic journals (e.g., all three general science journals at the time published psychological studies, and the field boasted two specialty journals compared to three for mathematics, two for chemistry, geology, and botany, and one for physics), the historical basis of psychology ("we may take pride in the beginnings of psychology whose foundations were more securely laid by Aristotle than those of any other science" [pp. 2-3]), and the strength of psychology in other countries. Cattell believed that the continued growth of psychology was dependent on the field's acceptance of quantitative methods similar to those used in other sciences. This belief was somewhat controversial: Although psychological laboratories were flourishing in the United States, the philosophical underpinnings of psychology led some to question the validity and, indeed, the necessity of psychological measurements. But Cattell felt that experimental approaches to psychology, especially those involving "psycho-physical" measurement, were critical to the rise and continued success of academic psychology: I venture to maintain that the introduction of experimental measurement into psychology has added directly and indirectly new subject-matter and methods, has set a higher standard of accuracy and objectivity, has made some part of the subject an applied science with useful applications, and enlarged the field and improved the methods of teaching psychology. In conclusion, I wish to urge that experiment in psychology has made its relations with the other sciences more intimate and productive of common good. (pp. 13-14). Cattell's approach to psycho-physical measurement (often referred to as anthropometric testing) was influenced by his brief work with Francis Galton in England before Cattell returned to the United States from his European studies. Cattell describes his laboratory's measurement work in his 1890 article in Mind (which includes an appendix by Galton) and his 1896 article with Livingston Farrand (Sternberg [1990] includes a brief summary of the 1890 article). Although it is widely believed that Cattell's goal was to measure intelligence or a similar construct with these tests, his goals appear to have been related for the most part to his goal of strengthening psychology's scientific credentials: We do not at present wish to draw any definite conclusions from the results of the tests so far made. It is of some scientific interest to know that students entering college have heads on the average 19.3 cm long, ... that they have an average reaction-time of 0.174 sec., that they can remember seven numerals heard once, and so on with other records and measurements. These are mere facts, but they are quantitative facts and the basis of science. Our own future work and that of others must proceed in two directions.... [a] To what extent are the several traits of body, of the senses and of mind interdependent? ... What can we learn from the tests of elementary traits regarding the higher intellectual and emotional life? [b] On the other hand we must use our measurements to study the development of the individual and of the race, to disentangle the complex factos of heredity and environment. (Cattell & Farrand, 1896, p. 648). As Cattell's thinking about these psychophysical measures developed, he appears to have viewed the data as evidence of a unitary intellect. This view was somewhat controversial, especially in light of the dissertation research of Clark Wissler, one of Cattell's laboratory assistants. Wissler found little evidence of general intellectual ability, since the correlations of the various psychphysical tests with each other and with external criteria (e.g., grades) were low. Controversy exists about both the quality of Wissler's research and both Wissler's and Cattell's reactions to it, but Wissler's work is often considered, in the words of Sternberg (1990), the "coup de grace" for anthropometric testing (p. 72).
Cattell's use of statistical methods and quantification of data helped in the development of American psychology as an experimental science. He was one of the first psychologists in America to stress the importance of quantification, ranking, and ratings. An outgrowth of this work, his experimentation with psychophysical testing, was influential in the popularization of mental testing within the psychological laboratory. However, anthropometric testing in general became controversial with the publication of Wissler's work.

Publications:
Cattell, J. M. (1890). Mental tests and measurements. Mind, 15, 373-380.
Measurements of the accuracy of recollection.  Science (1895).
Statistics of American psychologists.  American Journal of Psychology (1903).
The conceptions and methods of psychology.  Popular Science Monthly (1904).
The school and the family.  Popular Science Monthly (1909).
Psychology in America.  Science (1929).
Baldwin, J. M., Cattell, J. M., & Jastrow, J. (1898). Physical and mental tests. Psychological Review, 5, 172-179.
Cattell, J. M. (1896). Address of the president before the American Psychological Association, 1895. Psychological Review, 3 (2), 1-15 (in PDF format; large file size: 3.4 MB. Will open in new window).
Cattell, J. M. (1896). Physical and mental measurements of the students of Columbia University. Psychological Review, 3 (6), 618-648 (in PDF format; large file size: 5.6 MB. Will open in new window).

References:

Biographical Dictionary of North American and European Educationists (1997) Woburn Press, London

Cattell, J. M. (1896). Address of the president before the American Psychological Association, 1895. The Psychological Review, 3(2), 1-15.

Cattell, J. M., & Farrand, L. (1896). Physical and mental measurements of the students of Columbia University. The Psychological Review, 3(6), 618-648.

Grolier Multimedia Encyclopedia (1995) Grolier Electronic Publishing, Inc.

Sternberg, R. J. (1990). Metaphors of mind: Conceptions of the nature of intelligence. New York: Cambridge University Press.

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