Examining executive function in the second year of life: coherence, stability, and relations to joint attention and language.

Several theories of executive function (EF) propose that EF development corresponds to children's ability to form representations and reflect on represented stimuli in the environment. However, research on early EF is primarily conducted with preschoolers, despite the fact that important developments in representation (e.g., language, gesture, shared joint attention) occur within the 1st years of life. In the present study, EF performance and the relationship between EF and early representation (i.e., joint attention, language) were longitudinally examined in 47 children at 14 and 18 months of age. Results suggest that the 2nd year of life is a distinct period of EF development in which children exhibit very little coherence or stability across a battery of EF tasks. However, by 18 months, a subset of child participants consistently passed the majority of EF tasks, and superior EF performance was predicted by 14-month representational abilities (i.e., language comprehension and some episodes of initiating joint attention). This research suggests that the transition from foundational behavioral control in infancy to the more complex EF observed in preschool is supported by representational abilities in the 2nd year of life.