Intelligence Controversy: One Main Factor Or Many?

[W]idely cited contemporary psychometric models can best be understood to terms of a discrepancy between two earlier models, which began the controversy over whether intelligence comprises one main component or many. More specifically, Charles Spearman (1927) found one general factor (g) prevaded performance on all mental ability tests and Louis Thurstone (1938) did not. Spearman also found what he considered to be less important test-specific factors (e.g., arithmetic computations, vocabulary). In contrast, THurstone's results revealed seven broad broad factors, or primary mental abilities, which could be psychologically interpreted as comprising intelligence. Example primary abilities are Verbal Comprehension and Number Facility. (However, it should be noted that Thurstone and Thurstone (1941) did find evidence for g, in addition to the primary mental abilities, when they later tested a more representative sample of children.)


Spearman, C. (1927). The abilities of man. New York, NY: Macmillian.


Thurstone, L. L. (1938). Primary mental abilities. Chicago, IL: University of Chicago Press.


Thurstone, L. L., & Thurstone, T. G. (1941). Factorial studies of intelligence. Chricago, IL: University of Chricago Press.

-- Janet E. Davidson , Iris A. Kemp

from "The Cambridge Handbook of Intelligence"

Quoted on Fri Nov 2nd, 2012