Investigating the Dynamics in 18-36 Months Toddlers’ Vocabulary Acquisition

Abstract

Objectives: The purpose of this study was to determine whether there were changes in language ability and vocabulary usage of children aged 18 to 36 months by specific time points. Methods: A total of 1,152 Korean children’s Wordbank data based on the MacArthur-Bates communication development assessment (K M-B CDI) were used for analysis. Korean Wordbank data is divided into two sections according to the time of data collection, one is collected before 2003, and the other is collected between 2016-2017. Data from the 2-time points were divided into time point 1 group (n = 988), and time point 2 group (n= 164). The total score and category score of K M-B CDI were compared between the time points. In addition, the significance of differences in each vocabulary item was compared by performing differential item functioning analysis based on classical test theory and item response theory. Results: This study found that the group difference in total score was not significant. However, the differences in category scores were found to be significant in 7 of the total 24 categories, and the scores of the time point 2 group were found to be significantly higher than the time point 1 group in the 6 categories. In addition, 117 items out of a total of 641 items were analyzed to have a differential function. Conclusion: Given that children in time point 2 showed higher performance in the categories of function words, it can be inferred that changes in children’s language skills may appear over time, and the results of this study also confirmed the dynamics of early children’s vocabulary use patterns.