Dimensionality of executive functions and processing speed in preschoolers

Processing speed is a foundational cognitive ability strongly associated with executive functions in children. To precisely interpret children's results in measures of executive functions, it is important to identify variation that is due to differences in executive functions versus processing speed. In this study, we examined the dimensionality of executive functions and processing speed in 3-6 years old preschoolers over six months with two time points. Executive functions and processing speed (i.e., choice reaction time) were assessed using computer-based tests.Confirmatory factor analyses showed that executive functions and processing speed were divided into two dimensions (processing speed+inhibition+switching and updating) at both time points. Regarding executive functions, the findings indicate that in preschoolers, inhibition+switching is inseparable, but updating is separable from processing speed. Findings emphasize the need to critically evaluate the underlying characteristics of different executive function tasks to better understand the development of executive function and its associations with other cognitive and academic skills.Educational relevance statement: In this study, we examined dimensionality of executive functions and processing speed in preschoolers. Executive functions have been identified as important predictors for school readiness and later academic performance. To better understand individual differences in executive functions and their associations with other cognitive and academic skills in early childhood, accurate measures of executive functions are needed. However, there has been concern that other cognitive processes involved in performing various EF tasks might mask variation in executive functions proficiency. Processing speed is one potential source of measurement impurity in measures of executive functions. However, the evidence about the dimensionality of executive functions and processing speed among young children is limited. To precisely interpret the children's results in measures of executive functions, it is important to identify variation that is due to differences in executive functions versus processing speed.