title: The influence of fluid and crystallized intelligence on the development of knowledge and skills.
abstract: BACKGROUND
  Cattell's Gf-Gc distinction is quite generally recognized. However, the developmental part of the Gf-Gc theory of intelligence has not gained the same recognition. Results are inconsistent, but recent discussions emphasize the importance of homogeneity of samples with regard to education and language when investigating the developmental Investment theory.
  
  
  OBJECTIVE
  The aim of this study was to investigate the influence of Gf and Gc on the development of knowledge and skills in a sample of children in compulsory school who are homogenous with regard to level of education, age, and cultural background.
  
  
  METHODS
  Totally, 9,002 individuals from the evaluation through follow-up database born in 1972 and who left compulsory school in 1988 were included. These individuals were followed up in Grades 3, 6, and 9.
  
  
  METHODS
  Structural equation modelling was used, and autoregressive path models were fitted. All modelling was performed using Mplus version 6.1.
  
  
  RESULTS
  In the first step, a path model with a simplex structure was defined. However, a second model with direct relations of Gf on Gc in Grades 6 and 9 had better model fit, suggesting a continuous influence of Gf on Gc. However, no direct influence of Gf was found for the subject grades.
  
  
  CONCLUSIONS
  Due to the continuous influence of Gf on the measures of Gc throughout compulsory school, support for Cattell's (1987) Investment theory was found.
authors.affiliation: University of Gothenburg, Sweden; University West, Trollhättan, Sweden.
authors.forename: Cecilia
authors.initials: C
authors.lastname: Thorsen
authors.forename: Jan-Eric
authors.initials: JE
authors.lastname: Gustafsson
authors.forename: Christina
authors.initials: C
authors.lastname: Cliffordson
mesh_terms: D000124:Achievement; D000293:Adolescent; D001076:Aptitude; D002648:Child; D003210:Concept Formation; D005260:Female; D006801:Humans; D007361:Intelligence Tests / Q000706:statistics & numerical data*; D007858:Learning; D008137:Longitudinal Studies; D008297:Male; D017145:Models, Educational; D011340:Problem Solving; D011582:Psychological Theory; D011594:Psychometrics / Q000706:statistics & numerical data; D011597:Psychomotor Performance; D015203:Reproducibility of Results; D013850:Thinking
keywords: crystallized intelligence; fluid intelligence; grades; knowledge and skills