Effects of speaker types and L1 backgrounds on the linguistic complexity of learners’ writing

This study investigated the differences in linguistic complexity between different types of English users, including native speakers (NS), English as a foreign language (EFL) learners, and English as a second language (ESL) learners in terms of Kolmogorov complexity. Furthermore, we explored how first language backgrounds affect linguistic complexity. Our dataset contains 2272 argumentative essays produced by English NSs and upper-intermediate learners from four ESL and six EFL countries/regions. Results showed that significant differences existed between the writings of NS, EFL, and ESL regarding overall and syntactic complexity. Specifically, the rank of overall complexity (NS > ESL > EFL) indicates that learners from countries/regions with higher exposure to English tend to produce overall more complex writings. Concerning syntactic complexity, EFL learners produce the most complex writings, while NS produces the least complex, indicating that essays written by EFL learners contain the most fixed word order patterns. In contrast, no significant difference was detected in morphological complexity among the NS, ESL, and EFL groups, suggesting that native and upper-intermediate non-NSs exhibit a similar range of morphological forms in their writings. Additionally, our results showed a larger effect of first language backgrounds over English speaker types on linguistic complexity, thus informing teachers to implement targeted writing instructions for learners from different countries.