Exploring the differences in syntactic complexity between lay summaries and abstracts: A case study of The New England Journal of Medicine

This study explores the difference in syntactic complexity between lay summaries (LSs) and scientific abstracts holistically and across their common rhetorical moves. Twenty-three syntactic complexity indices were employed to analyze a corpus of LSs and their counterpart abstracts from The New England Journal of Medicine. The analyses revealed that the LSs employed significantly shorter production units, more subordinate structures, more verb phrases, but fewer coordinate phrases and fewer complex nominals. Notably, the number of specific noun modifiers within complex nominals did not differ significantly between the two groups, indicating a comparable level of nominal sophistication. Moreover, we observed significant differences in the syntactic complexity of sentences realizing the common rhetorical moves across the two genres. Specifically, sentences introducing background and presenting results were syntactically simpler in the LSs, whereas the syntactic complexity of sentences summarizing methods and drawing conclusions remains largely consistent across both groups. The study contributes to a deeper understanding of the linguistic features of LSs and offers useful implications for LS writing practice.