Fluid/spatial and crystallized intelligence in relation to domain-specific working memory: A latent-variable approach

Fluid/spatial intelligence, crystallized intelligence and their relationships to verbal and visuospatial working memory (WM) were studied. A total of 120 Finnish Air Force recruits participated in this study. Fluid/spatial intelligence was assessed using four different tasks, while crystallized intelligence was defined with the help of test scores of Finnish upper secondary school National Matriculation Tests in three different academic subjects and one additional Verbal Relations task. Complex WM span tasks were used to measure visuospatial and verbal WM capacities. Structural equation modeling indicated that verbal WM was related to crystallized intelligence when both WM tasks were included in the model, whereas performance on the visuospatial WM task was related to fluid/spatial intelligence, but not to crystallized intelligence. Verbal WM was not related to fluid intelligence when used as a single WM predictor. The results indicate that verbal WM might be related to verbal ability and learning at school, while visuospatial WM is relatively strongly related to nonverbal reasoning and spatial visualization. The current results further suggest that WM capacity is not a unitary system. D 2004 Elsevier Inc. All rights reserved.