Investigating lexical knowledge and lexical processing in order to explore their role in second language utterance fluency

Research has found that lexical knowledge substantially influences second language (L2) fluency. However, researchers investigating the role of L2 lexical knowledge on speakers' fluency have often measured lexical knowledge with written recognition tasks, which creates a mismatch between the assessment modality and the oral, productive skill. Furthermore, although some studies have considered the role of lexical processing (e.g., lexical retrieval and articulation) when researching utterance fluency, results have been mixed. The current study adds to this scholarship by using mainly productive tasks to investigate possible relationships among measures of L2 lexical knowledge and processing and to explore their role in L2 utterance fluency. High-intermediate language learners (n = 30) in an intensive English program were assessed on their lexical knowledge (i.e., form recall, meaning recognition and sentence production), oral processing (i.e., lexical retrieval speed), and articulation (i.e., preparation time and duration). Utterance fluency was measured with pause length, number of pauses, and syllable duration during a monologic topic-based speech. Correlational analysis revealed a negative correlation between form recall and lexical retrieval time, meaning that L2 learners who could recall more words retrieved them faster. Regression analyses revealed that lexical meaning scores predicted pause length, articulation preparation time predicted mean number of pauses, and lexical retrieval predicted syllable duration. The results suggest that the lexical knowledge, lexical retrieval speed, and the phonological/phonetic system (i.e., articulation preparation) are clearly and differentially involved in utterance fluency in high-intermediate speakers.