The Role of Executive Function for Vocabulary Acquisition and Word Learning in Preschool-Age Children with and without Vocabulary Delay

Objectives: The development of executive function (EF) in childhood can be understood in terms of 'consciousness' development. As age increases, the potential of conscious control of thoughts and behaviors for child can be increased. This study examined the relationship of EF and word learning in children with and without vocabulary delay (VD). Methods: Thirty-five 5-to-6-year-old children with VD and 35 age-matched children with typically developing (TD) participated in this study. Participants' performance was assessed with Quick Incidental Learning (QUIL) for novel word learning, nonword repetition (NWR) for working memory, the Stop Signal Task (SST) for inhibitory control, and the Dimensional Change Card Sort (DCCS) for cognitive flexibility. Accuracy and reaction time in the SST and DCCS were obtained using E-Prime Software; only accuracy was measured in the QUIL and NWR task. MANOVA, correlation, and stepwise multiple regression were used for data analysis. Results: The results showed that the VD group had significantly lower accuracy on the QUIL and NWR, poorer performance on the DCCS, and longer reaction time on the SST than the TD group. The strongest predictor of novel word learning was accuracy in DCCS for the VD group. Conclusion: These results indicate that children with VD require conscious effort to activate their EF instead of learning novel words automatically like their typically developing peers, who acquire new words relatively easily without additional cognitive burdens.