Although research clearly supports the validity of general intelligence as a predictor,some researchers believe that conceptualizing intelligence merely as g encourages oversimplification of the inherent complexity of intelligence. Murphy (1996) asserted that intelligence is not a unitary phenomenon, and other dimensions of intelligence are also worthy of our consideration. Ackerman (1992), for example, reported superior predictive power of multiple abilities over general intelligence in complex information-processing tasks, as in the job of air traffic controller. Ackerman and Kanfer (1993) developed a useful selection test for air traffic controllers based in large part on the assessment of spatial ability. From an I/O psychology perspective, therefore, the controversy regarding the assessment of intelligence rests primarily on the adequacy of measuring general intelligence (g) only or assessing multiple cognitive abilities in forecasting job behavior. The current body of research seems to indicate that‘in most cases measuring the g factor of intelligence offers superior predictive accuracy in forecasting success in training and job performance over measuring specific (math, spatial, and verbal) cognitive abilities (Carretta 8C Rec, 2000; Roznowski et al., 2000). Salgado et al. (2003) likewise demonstrated general mental ability forecasts success in training and on the job in a major study of ten European countries.