The role of Thurstone's multidimensional model.
The model of the modern Binet represents an attempt to place an evaluation of g in the context of a multidimensional model of intelligence from which one can evaluate specific abilities. The impetus for a multidimensional model stemmed from the work of Thurstone (1938). He argued that, contrary to Spearman's notion of intelligence as a single process, intelligence could best be conceptualized as comprising independent factors, or "primary mental abilities." Years of painstaking work ultimately revealed evidence for group abilities factors that were relatively, but not totally, independent. The group factors were correlated, and from them a g factor could be extracted, as in the hierarchical model of the modern Binet.