Screen-based reading has frequently been associated with lower comprehension than reading on paper, a phenomenon known as screen inferiority. Although cognitive capacity, linguistic knowledge, and digital usage vary across learners, it remains underexplored how individual-difference factors shape medium effects in second-language (L2) reading among adolescents. We investigated how reading on paper versus tablets affects L2 reading comprehension among 240 Korean eighth graders learning English and whether medium effects are moderated by working memory, L2 proficiency, and tablet experience. Participants completed comprehension tests under both conditions, along with a reading span task, a proficiency test, and a tablet-usage questionnaire. Results showed that participants performed worse on tablets than on paper; these gaps were larger among learners with higher spans and proficiency. In contrast, tablet experience did not interact with reading medium. These findings underscore the need for explicit instruction to support effective L2 reading on digital devices, even for high-performing learners.
