Understanding child executive functioning through use of the Bornstein specificity principle

A focus on intraindividual change and person-specific pathways is a necessary starting point for developmental science inquiries. However, research often relies on ergodicity-based assumptions about group averages and other variable-centered approaches. Using ideas associated with relational developmental systems metatheory, such as the Bornstein Specificity Principle, we re-examine the ergodicity assumption using Executive Functioning (EF) data from the Measures and Methods Across the Developmental Continuum Project. Participants from Grades 4 to 12 (M age = 14.60) completed three behavioral EF tasks (i.e., working memory, response inhibition, and cognitive flexibility). The final analytic sample included 64 participants who provided data on 30 measurement occasions. Intraindividual and interindividual EF latent constructs appeared to be different, and we identified a wide range of person-specific EF trajectories. These findings challenge the ergodicity assumption framing variable- and group-oriented approaches to individual development. This study demonstrates the feasibility of collecting intensive longitudinal data to understand youth development on an individual level as an alternative to immediate data aggregation and as means to illuminate the use of the specificity principle in understanding human development and in applications pertinent to enhancing the lives of diverse youth across specific times and places in their specific developmental pathways.