g, mutualism, and development: Cross-sectional evidence from Iranian schoolchildren

Different models might explain one the most replicated findings in Psychology, namely, the positive correlation among diverse tests of cognitive ability (positive manifold). The g factor and the mutualism models are examples. Mutualism suggests that the manifold emerges progressively during development, as a consequence of interactions among originally uncorrelated cognitive process. The g factor model departs from this perspective and assumes that there is an underlying latent factor remaining fairly constant across development. The present study investigates these two approaches considering 661 children (age range = 6 to 12 years) recruited from primary school in Tehran. A wide set of cognitive tests, selected under the CHC framework, was completed by these individuals. First, the measurement model was tested across age for demonstrating that the factor of interest is properly tapped by the administered measures. Afterwards, the scores were submitted to statistical analyses for testing the models' prediction: the mutualism approach predicts stronger correlations among scores as individuals grow up, whereas the g model does not. Results revealed metric invariance regarding the obtained g factor across the age range. Furthermore, the amount of variance explained by this factor remained fairly constant. In conclusion, the findings were consistent with the g model.