The interplay of semantic predictability and vocabulary knowledge in second-language stress processing

Efficient use of predictive context can offset prosodic uncertainty in second language (L2) speech. This study examined how semantic predictability and individual differences in L2 vocabulary knowledge modulate lexical-stress processing during L2 spoken word recognition. Eighty Korea learners of English completed an auditory lexical decision task in which multisyllabic targets—real words or pseudowords created by stress-shifting real words—appeared sentence-final in predictable or neutral contexts. Vocabulary knowledge was assessed with a vocabulary size test. Mixed-effects models assessed response times and accuracy as a function of context, vocabulary size, and their interaction. Results showed that predictable contexts accelerated lexical decisions, and this benefit expanded for learners with larger vocabularies, suggesting that richer lexicons sharpen the use of semantic expectations when stress cues are uncertain. Vocabulary size alone did little for response speed in neutral contexts, implying that vocabulary knowledge and context work in concert rather than additively. Accuracy was high; although influenced by context and vocabulary, it showed no interaction, confirming that timing measures captured the key variation. These findings support a dynamic-weighting view in which lexical knowledge fine-tunes how L2 listeners balance top-down predictions against bottom-up prosodic information, indicating that vocabulary growth can foster faster, context-driven processing during spoken word recognition.