British psychologist who theorized that a general factor of intelligence, g, is present in varying degrees in different human abilities.

While serving as an officer in the British army (1883–97), Spearman came to believe that any significant advance in philosophy would come about mainly through psychology. Over the next 10 years he worked intermittently with Wilhelm Wundt (Wundt, Wilhelm), the founder of experimental psychology, at the University of Leipzig, and he took his Ph.D. there. He joined the faculty of University College, London (1907), and was professor there from 1911 to 1931.

Spearman's attempt to establish general, fundamental laws of psychology was based on his statistical work in determining correlations among mental abilities, reflected in his classic paper, “ ‘General Intelligence,' Objectively Determined and Measured” (1904). He sought to interpret correlations among several variables on the basis of a specific factor for each variable and a factor common to all. Because measures of seemingly different mental abilities consistently indicate correlations, he concluded that the prevalence of positive correlations must result from the general factor, g. By 1912 he and a coworker had developed an order of correlation coefficients separating various performances into the general factor, g, and varying specific factors, s₁, s₂, and so on. The fullest account of his work is to be found in The Abilities of Man (1927). His historical survey, Psychology Down the Ages, 2 vol. (1937), was followed by Human Ability (1950, with L.W. Jones).