Beyond Length: Investigating Dependency Distance Across L2 Modalities and Proficiency Levels

As an important index of working memory burden and syntactic difficulty, Dependency Distance (DD) has been fruitfully applied in the context of Second Language Acquisition (SLA) to both native and non-native language production. Recent research has focused on DD as a predictor of writing performance across different proficiencies, while the other modality of second language (L2) performance - speaking - has been largely neglected. Moreover, while previous results reported significant positive correlations between DD and writing proficiency, a lack of control for important variables such as sentence/text length may have potentially inflated the outcomes of the analyses. In this study, we examine the effects of DD across the different modalities and proficiency levels, controlling for the effects of text and sentence lengths. Results from statistical analysis show that the mean DD of L2 writing is significantly shorter than L2 speech production, indicating that L2 writing may be a cognitively more demanding task than L2 speaking. Additionally, while significant statistical differences in DD were found across proficiency levels in both L2 writing and speech, the significance disappeared after controlling for sentence and text length. The implications of the present study for future research on DD in SLA are discussed.