Evaluating competing models of the relationship between inspection time and psychometric intelligence

Confirmatory factor analysis (CFA) was used to test models of the relationship between inspection time (IT) and psychometric measures of intelligence (the eleven subtests of the Wechsler Adult Intelligence Scale-Revised). The sample consisted of 134 healthy adults and was broadly representative of the adult United Kingdom population in terms of the distributions of age and social class. A Nested Factors parameterization consisting of g plus three orthogonal group factors with IT loading on all factors provided a reasonably good fit to the data. Variants on this model that incorporated theoretical and empirically derived constraints were tested; constraining IT to have zero loadings on all factors produced a significant deterioration in fit. Constraining IT to load only on General Intelligence (g) and Perceptual Organization did not produce a significant deterioration; nested variants on this latter model in which IT was constrained to load on either of these two factors alone produced a significant deterioration in fit.