Dependency distance reflects L2 processing difficulty: Evidence from the relationship between dependency distance, L2 processing speed, and L2 proficiency

Aims and objectives: This study aims to investigate whether dependency distance (DD) can reflect L2 processing difficulty by exploring the relationship between DD, L2 processing speed, and L2 proficiency.Methodology: The sentences in a maze task were annotated based on dependency syntax to indicate L2 processing difficulty. The maze task then was used to capture the word-level and sentence-level processing speed. The task was successfully performed by 62 Chinese learners of English, who were assigned into an intermediate-level group and an advanced-level group according to their scores on an elicited imitation task (EIT) and a vocabulary and grammar test.Data and analysis: Reaction time (RT) data of processing word-level and sentence-level items were collected from the maze task. The DD-based estimates of word-level and sentence-level processing difficulty were calculated. Generalized linear regression models (GLMs) were employed to inspect the relationship between the DD-based estimate of processing difficulty, L2 processing speed, and L2 proficiency.Findings: Our results showed that DD significantly predicted L2 processing speed at both word and sentence levels, irrespective of participants' L2 proficiency. As DD increased, advanced learners' word-level processing time grew significantly slower than that of intermediate learners.Originality: Using psycholinguistic experiments, the study is one of the first attempts to empirically validate the effectiveness of DD in capturing L2 processing difficulty.Significance: Our findings suggest that DD is useful in predicting L2 processing difficulty, and the extent to which learners are able to efficiently process dependencies with increasing distance can differentiate their L2 proficiency levels.