Integration of syntactic and prosodic boundary cues in second language processing

Recent research has explored factors influencing second language (L2) prosody–syntax integration, such as proficiency, language transfer, and processing strategies. However, it remains unclear whether L2 processing resembles native mechanisms. This study aimed to examine L2 prosody–syntax integration by comparing English sentence processing between native English speakers and Chinese L2 learners, and first language (L1) Chinese and L2 English processing within L2 learners. Eighty-nine participants (30 native speakers, 30 higher-proficiency, and 29 lower-proficiency learners) completed Rapid Prosody Transcription experiments. The strengths of acoustic cues were manipulated across nine steps at syntactically licensed and unlicensed positions. Results showed syntactic constraints and salient acoustic cues independently influenced prosodic boundary judgments in L1 and L2. Compared with native speakers, Chinese L2 learners exhibited a stronger reliance on syntactic information in English. Moreover, L2 learners depended more on L2 syntax than L1 syntactic knowledge, indicating limited transfer from their native language. These findings highlight an interaction between syntax and prosody in L2 processing, consistent with parallel-processing models. The reliance on syntactic knowledge in sentences with unambiguous structures refines the scope of the Shallow Structure Hypothesis, which originally proposes that L2 learners are less sensitive to syntactic constraints and rely more on non-structural information.