The influence of L2 proficiency on letter position encoding and sentence processing of bilinguals: Evidence from a reading-like task

Aims and objectives: Prior research on orthographic encoding has predominantly focused on the first language (L1) domain. In contrast, studies exploring the second language (L2) domain remain relatively scarce. This study aims to investigate L2 orthographic encoding at the sentential level. Furthermore, it examines the dynamic changes in orthographic encoding patterns as L2 proficiency improves. Methodology: Thirty high and low L2 proficiency participants are asked to do a reading-like task in which target words are embedded into the experimental sentences, and whose eye movement measures are recorded. Transposed-letter (TL) cost was employed to gauge the strictness of letter position encoding. A larger TL cost indicates a relatively strict pattern of letter position encoding. Conversely, a smaller TL cost implies flexibility in this encoding process. Data and analysis: Data were analyzed using linear mixed-effects regression (LMER) in the R environment. Bonferroni correction was applied to address the issue of multiple comparisons. Findings: Bilinguals with different L2 proficiency exhibited distinct letter position encoding pattern. Specifically, bilinguals with high L2 proficiency showed a larger TL cost, indicating a strict pattern of letter position encoding; in contrast, those with low L2 proficiency showed a smaller TL cost, reflecting a flexible pattern. These results suggest that L2 proficiency influences bilinguals’ L2 letter position encoding, which manifests as a dynamic pattern: as L2 proficiency increases from low to high, bilinguals’ L2 letter position encoding shifts from flexibility toward strictness. Originality: The dynamic pattern of letter position encoding in bilinguals identified in this study—encoding pattern shifts from flexibility toward strictness as L2 proficiency increases from low to high—provides empirical evidence for the lexical tuning hypothesis. Implications: This study enriches the theoretical framework of L2 lexical access, with specific contributions to the lexical tuning hypothesis at the orthographic level.