Although many tasks have been developed recently to study executive control in the preschool years, the constructs that underlie performance on these tasks are poorly understood. In particular, it is unclear whether executive control is comprised of multiple, separable cognitive abilities (e.g., inhibition and working memory) or whether it is unitary in nature. A sample of 243 normally developing children between 2.25 and 6 years of age completed a battery of ageappropriate executive control tasks. Confirmatory factor analysis (CFA) was used to compare multiple models of executive control empirically. A single-factor, general model was sufficient to account for the data. Furthermore, the fit of the unitary model was invariant across subgroups of children divided by socioeconomic status or sex. Girls displayed a higher level of latent executive control than boys, and children of higher and lower SES did not differ in level. In typically-developing preschool children, tasks conceptualized as indices of working memory and inhibitory control in fact measured a single cognitive ability, despite surface differences between task characteristics.Keywords: executive control, inhibition, working memory, preschool, confirmatory factor analysis Preschool Executive Control 3Using confirmatory factor analysis to understand executive control in preschool children:I. Latent structure Executive control is a term used to refer broadly to those cognitive abilities that are associated with, or subserved by, prefrontal cortex and interconnected subcortical system (Diamond, 2001;Stuss, 1992). Although research on executive control has been underway for several decades, remarkably there remains no well-agreed-upon definition as yet. One school of thought has conceptualized executive control as a group of relatively independent, or fractionated, cognitive abilities, typically including working memory, the ability to keep information in mind to guide ongoing or later behavior (Baddeley & Hitch, 1974); inhibitory control, the ability to keep irrelevant or misleading information from interfering with performance (Diamond, 1990;Harnishfeger & Bjorklund, 1993); and set-shifting, or adapting strategies to changing situational demands (Zelazo, Frye, & Rapus, 1996). In contrast, others have argued that executive control is a unitary, domain general construct that manifests in different ways depending on contextual demands (e.g., Duncan & Miller, 2002;Duncan & Owen, 2000).Prefrontal systems undergo a protracted course of development (Benes, 2001). In comparison with posterior cortical areas, the phases of prefrontal cortical development, including neuronal generation, differentiation, and synaptic pruning, occur later and over a longer period of time (Giedd et al., 1999;Huttenlocher, 1990). Myelination of fibers within prefrontal cortex is not complete until early adulthood (Paus et al., 2001). Executive control undergoes a similarly delayed developmental trajectory where, for example, performance on "classic" executive tasks like the T...
