Charles Edward Spearman was born in London on September 10, 1863, into a respected family. As a student, he demonstrated a superb mastery of mathematics and
science but held a “secret devotion to philosophy” that would last his entire life (1930, p. 299). Following graduation from college, Spearman secured a commission as an officer in the Royal Engineers of the British Army. Spearman was assigned to a post in Burma, where he served honorably and rose to the rank of major. During this time, his continued interests in philosophy led to the belief that many of the debated issues of philosophy could be resolved successfully by applying the empiricism of psychology. So at the age of 34, Spearman abandoned a successful military career and began study in the Leipzig laboratory of Wilhelm Wundt. Despite his obvious military success, Spearman later portrayed his 14 years of service as “the greatest mistake of my life, [based on] the youthful delusion that life is long.” (1930, p. 300).
Although Wundt is considered a founding father of psychology, Spearman's greatest influence came from Sir Frances Galton (1822–1911). After reading Galton's Hereditary Genius (1869) and Inquiries into Human Faculty and Its Development (1883), Spearman seized on two principles that guided the remainder of his life's work. First, individual differences in sensory, motor, and cognitive abilities may be measured precisely using standardized techniques. Second, there exists a biologically based general mental ability that enters into every kind of mental activity.
At his own personal expense and without the support of Wundt, Spearman conducted a study to test the Galtonian notion that individual differences in sensory discrimination and modality were positively correlated with varied measures of cognitive ability. As the logic goes, positive correlations among the variables would demonstrate the existence of a common source of variation (i.e., the presence of a general ability). To accomplish his aim, Spearman invented the statistical technique of factor analysis to analyze the matrix of correlations among variables. Spearman published this study as a 1904 article titled “‘General Intelligence’, Objectively Determined and Measured.” The article garnered considerable scientific interest, both for its surprising support of Galton's theory of general ability, as well as its innovative statistical methodology. Following further military service in the Boer War, Spearman finally completed his doctoral study in experimental psychology in 1906. By that time he was 42 years of age but with “more distinguished scientific accomplishments to his credit than probably any other new Ph.D. in the history of psychology” (Jensen, 2000, p. 4).
Spearman joined the Department of Experimental Psychology at University College, London, where he was promoted to full professor in 1911. He continued his research into general ability and expanded investigations to include group differences, psychometrics, eugenics, and learning. Spearman retired in 1931, but continued to play an active role in field of educational psychology. After retirement, Spearman taught in North America at Columbia University, where his students included David Wechsler and Raymond B. Cattell.
During his esteemed career, Spearman received numerous honors, including Fellow of the Royal Society and membership in the United States National Academy of Science. In 1945, with failing health at age 82, Spearman reportedly committed suicide by jumping from a window of the London University Hospital, where he was a patient.
Spearman is credited with offering the first truly tenable psychometric definition of intelligence and is, therefore, considered to be the founding father of classical test theory. This approach, which considers an individual's observed score as consisting of a true score plus error score has been particularly influential in test development and conceptions of reliability. Spearman's best known contribution to statistics is the rank-order correlation coefficient, a nonparametric index of association between two ordinal variables. Additionally, Spearman's development of factor analysis is the first direct application of latent trait theory, which advances that individual differences in observed test scores serve as reflections of some smaller number of hypothetical, or latent, variables. This technique is routinely used to determine the construct validity of tests. Undoubtedly, Spearman's most important discovery was the identification of a general factor of mental ability (i.e., Spearman's g or g factor). A century of research finds that Spearman's g is the largest singular source of individual differences in mental ability and learning, regularly accounting for approximately half of the variance in test scores (Jensen, 1998).
Since its explication in Spearman's seminal 1904 article, the g factor has garnered considerable support and controversy. The continued interest and influence of Spearman's research can be traced to a number of developments, including the spread of universal public education, an increased range in the intelligence and scholastic achievement of the school population, and the rising cognitive demands of a complex modern society and workplace. In the early 2000s, one of the liveliest and most productive lines of research in cognitive neuroscience and biogenetics is the search for the physiological/genetic provenance of Spearman's g (Brand, 1996; Meisenberg, 2005). As testimony to his originality and continued influence, Spearman is one of the few psychologists showing an increasing rate of citations since his death.
See also:Intelligence: An Overview
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. London: Macmillan.
Spearman, C. (1927). The abilities of man: Their nature and measurement. 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.
Brand, C, R, (1996). The g factor: General intelligence and its implications. New York: Wiley & Sons.
Jensen, A. R. (1998). The g factor: The science of mental ability. Westport, CT: Praeger.
Jensen, A. R. (2000, March). Portraits of the pioneers: Charles Spearman. Newsletter of the Galton Institute, 36, 3–7.
Meisenberg, G. (2005). Genes for intelligence. A review of recent progress. Mankind Quarterly, 36, 139–164.