His research not only led him to develop the concept of the g factor of general intelligence , but also the s factor of specific intellectual abilities .
Charles Spearman developed his two - factor theory of intelligence using factor analysis .
Charles Spearman 's research not only led him to develop the concept of the g factor of general intelligence , but also the s factor of specific intellectual abilities .
Charles Spearman developed his two - factor theory of intelligence using factor analysis .