The complexity effect phenomenon is an epiphenomenon of age-related fluid intelligence decline

Abstract

This paper employs the methods of covariance structure analysis to explore the relationship between complexity, age, and fluid intelligence. Fluid intelligence is defined by seven psychometric tests. Complexity is systematically varied by making two well-known measures of fluid intelligence progressively more simple. The model assumes the existence of three psychometric factors—fluid intelligence with loadings from all psychological tests including those whose complexity was manipulated, and two narrow factors (the Swaps and Triplets factors) representing only complexity levels of a given test. The results show that age is related to the general fluid intelligence factor—it does not seem to have direct links with different levels of complexity manipulations. It is argued that the often observed tendency for the magnitude of age differences in performance to increase as the task becomes more complex—known in the literature as the Complexity Effect Phenomenon—is a consequence of the fact that fluid intelligence correlates with age.