Executive function refers to the higher-order cognitive control process for the attainment of a specific goal. There are several subcomponents of executive function, such as inhibition, cognitive shifting, and working memory. Extensive neuroimaging research in adults has revealed that the lateral prefrontal cortex plays an important role in executive function. Developmental studies have reported behavioral evidence showing that executive function changes significantly during preschool years. However, the neural mechanism of executive function in young children is still unclear. This article reviews recent near-infrared spectroscopy (NIRS) research that examined the relationship between the development of executive function and the lateral prefrontal cortex. Specifically, this review focuses on cognitive shifting, inhibitory control, and working memory in young children. Research has consistently shown significant prefrontal activation during tasks in typically developed children, but this activation may be abnormal in children with developmental disorders. Finally, methodological issues and future directions are discussed.

Executive function (EF) refers to the ability to execute appropriate actions and to inhibit inappropriate actions for the attainment of a specific goal. Research has shown that this ability develops rapidly during the preschool years. Recently, it has been proposed that research on executive function should consider the importance of social interaction. In this article, recent evidence regarding the early development of executive function and its relation to social interaction has been reviewed. Research consistently showed that social interaction can influence executive function skills in young children. However, the development of executive function may facilitate the cognitive skills that are important for social interaction. Taken together, there might be functional dependency between the development of executive function and social interaction.

Prior research has documented that Japanese children's performance on the Dimensional Change Card Sorting (DCCS) task can be influenced by their observation of another person completing the task, which is referred to as social transmission of disinhibition. The current study explored whether Canadian children would also show a social transmission of disinhibition and whether their performance would be comparable to that of Japanese children. In this study, 3- and 4-year-olds in Canada and Japan were given both the standard version and social version of the DCCS. Results indicated that Canadian children displayed the social transmission of disinhibition, but their effects were significantly weaker than those with Japanese children. On the other hand, performance on the standard DCCS was comparable between children in the two countries. We discuss the results in terms of cultural differences in the relationship between self and other.

Socioeconomic status (SES) has a powerful influence on cognitive, social and brain development. Children from low-SES backgrounds show poor executive function (EF). However, it is unclear if there is a SES-dependent disparity in functional brain development. The present study examined whether the SES of preschool children (N = 93) is associated with prefrontal activation during cognitive shifting tasks as measured by near-infrared spectroscopy. Low-SES children did not show activation in lateral prefrontal regions during the tasks, whereas middle- and high-SES children showed prefrontal activations, although no differences were found in terms of behavioural performance. These results suggest that SES can affect the functional development of the prefrontal regions. In this study, we discuss the practical implications of the results.