The 'IQ' factor: implications for intelligence theory and measurement
Journal/Book: Pers Indiv Differ. 1999; 27: the Boulevard Langford Lane, Kidlington, Oxford Ox5 1GB, England. Pergamon-Elsevier Science Ltd. 715-735.
Abstract: The history of intelligence test development is considered with special reference to the drift away; from verbal tests and to the contemporary assumption that every factor produced by statistical analysis of cognitive performance variables is an 'intelligence' factor. To test this assumption of universal test validity the Wechsler Adult Intelligence Scale (WAIS) and Raven's Advanced Progressive Matrices (RAPM) test were administered to 76 subjects, with equal numbers of males and females and ages representing the whole adult life-span. Principal components analyses (PCA) and multiple linear regression analyses (MLR) demonstrated that age and sex account for 3% of the variance of IQ scores' as compared to 1, 28 and 64% for Cattell's 'Gc','Gsar', and 'Gf factors, respectively. In addition, with IQ as a marker variable, and including age and sex, PCA was used to ascertain factor loadings for IQ on the three G factors, The highest loading of 0.77 was found for Gc whereas the loadings for Gsar and Gf were only 0.31 and 0.19, respectively. These results support the conclusion that while there are multiple cognitive performance factors there is only one IQ factor and therefore only one valid intelligence factor. Theoretical, social and research implications are discussed.
Note: Article Robinson DL, Kuwait Univ, Fac Med, Dept Community Med & Behav Sci, POB 24923, Safat 13110, KUWAIT
Keyword(s): age; ageism; brain function; intelligence; IQ; sex