Key points are not available for this paper at this time.
The study of William Brown and William Stephenson, “A Test of the Theory of Two Factors,” is re-analyzed by means of the Thurstone multiple factor methods. No tests or correlations are left out of the original table of correlations as is done in the original analysis in an attempt to validate the two-factor theory. Space, verbal, and perceptual speed factors similar to those found by Thurstone, Wright, and Garrett are identified. A common factor of “Maturation” is postulated to account for the remaining communality of the tests. A fifth factor is considered to have no significance due to the small amount of variance which it contributes to the total.
Robert I. Blakey (Sat,) studied this question.