Perspectives on fluid and crystallized intelligence: facets for verbal, numerical, and figural intelligence

Fluid intelligence is often measured with figural tests, whereas crystallized intelligence is often assessed with verbal tests. It is argued that construct-irrelevant figural variance is included in fluid intelligence and construct-irrelevant verbal variance is included in crystallized intelligence. The specification of a content facet comprising verbal, numerical, and figural abilities for fluid and crystallized intelligence would reduce the construct irrelevant variance. This faceted view of fluid and crystallized abilities is regarded as more convincing than a purely hierarchical structure. Although the present approach is partly similar to Guttman’s Radex model, no radial partitioning of the tasks is expected. Seven hundred and six German participants aged between 14 and 50 years were tested with the I-S-T 2000, a test comprising verbal, numerical, and figural reasoning tasks, as well as verbal, numerical, and figural knowledge tests. In smallest space analysis, a simplex for fluid and crystallized intelligence emerged as well as a radial or a polar facet for verbal, numerical, and figural content. The faceted structure for fluid and crystallized intelligence was also shown in confirmatory factor analysis and fitted the data more completely than the hierarchical model. The implications for the conceptualization and the assessment of fluid and crystallized intelligence are discussed.