Differentiation hypotheses of intelligence: A systematic review of the empirical evidence and an agenda for future research.

The stability of cognitive abilities: A meta-analytic review of longitudinal studies.

“…This finding is somewhat inconsistent with predictions based on the ability differentiation hypothesis. As the ability differentiation hypothesis states that general intelligence accounts for less systematic variance of cognitive performances in high-ability individuals, it would predict that the stability of composite measures of general intelligence decreases with increasing ability level (e.g., Breit, Brunner, et al, 2022). The absence of this effect may be due to the ability differentiation effect being not very consistent in children (Breit, Brunner, et al, 2021), and given the large number of studies based on samples of children in the present meta-analysis, this may significantly reduce the overall impact of the ability differentiation effect.…”

“…The ability differentiation hypothesis states that the structure of cognitive ability changes across the continuum of the general cognitive ability g. Whereas the overall factor structure appears to be constant, the relative importance of g for individual test performances decreases with increasing g-level (Breit, Brunner, et al, 2022;Tucker-Drob, 2009). This ability differentiation effect implies a decrease in systematic variance in measures of general intelligence with increasing g-level, leading to a gradual reduction of test-score reliability (Breit, Brunner, et al, 2022). Because testretest correlations cannot exceed the reliability of the utilized test, This document is copyrighted by the American Psychological Association or one of its allied publishers.…”

“…Second, ipsative continuity represents the stability of an individual’s configuration of different scores—their ability profile—over time. Research on age differentiation effects has shown that the strength of cognitive profiles remains relatively uniform across childhood and adolescence and decreases toward the end of life (Breit, Brunner, et al, 2022). There is some tentative evidence that cognitive ability profiles have little temporal stability in low-ability samples (McDermott et al, 1992; Watkins & Smith, 2013) but moderate stability in high-ability samples (Breit, Scherrer, et al, 2021).…”

Academic profile development: An investigation of differentiation processes based on students’ level of achievement and grade level.

“…Nonlinear factor analysis therefore allows to investigate which and to what extent specific ability scores differentiate from g-and therefore from the common variance of all specific ability scores-with increasing ability level, age, and their product. The method has been used in many investigations of intelligence structure differentiation (see Breit et al, 2022, for a review).…”

“…Spearman therefore concluded that as the level of g increases, the impact of g on observed test scores decreases. Since cognitive subtests are less correlated with increasing level of g , this effect leads to more pronounced profiles of cognitive strengths and weaknesses in high ability individuals (e.g., Breit et al, 2022). In other words, the profile scatter increases with increasing profile altitude.…”