Abstract
The purpose of this study is to investigate the changes of noun phrase complexity and its factors in the process of learning essay writing in English through the analysis of a longitudinal leaner corpus. Since Biber et al. (2011) claimed the importance of the complexity of noun phrases in English writing, there have been many studies conducted to analyze the complexity of noun phrases. Kim (2021) used a longitudinal Korean learner corpus of English to report that the noun phrase complexity alone significantly decreased among five syntactic features. In order to verify Kim’s report, the current study using a 290-thousand-word longitudinal Japanese learner corpus of English calculated the syntactic features by means of Lu’s (2010) Syntactic Complexity Analyzer and conducted generalized linear mixed modeling, showing that contrary to Kim’s result the complexity of noun phrases increased significantly. Once the order of topics was taken into further analysis, the order of topics modulated the effect of the noun phrase complexity even though essay scores increased longitudinally regardless of the topic order differences. It could be concluded that the noun phrase complexity is affected by topic differences greater than the effect of essay score increase.
