The Effects of Interleaved Spaced Repetition Learning on Vocabulary Knowledge

Abstract

Spaced repetition in Second Language Acquisition (SLA) research is a popular area of study, but few studies explore the learning of various aspects of word knowledge (Nation, 2001). Interleaved Spaced Repetition Software (ISRS) combines the principles of task interleaving (i.e., the reoccurring practice or study of multiple skills/concepts) and spaced repetition (i.e., interval-based study). This study enrolled 74 Japanese university EFL learners over two academic semesters to assess their acquisition of the New Academic Word List’s (NAWL; Browne et al., 2013) word items supplemented with contextualized sentences, word/sentence audio and L1 translations (eNAWL; Kanazawa & Lafleur, 2023) while utilizing Interleaved Spaced Repetition Software (ISRS; i.e., digital flashcard study software) developed by the author. Some important findings were the uneven word knowledge pretest scores: “Meaning” (24.34%), “Form” (20.53%) and “Use” (13.16%), and the relatively even posttest score gains as encouraged by ISRS’s task interleaving algorithm: “Meaning” (+16.71%), “Form” (+15.39%), and “Use” (+13.16%). Finally, the treatment group significantly outperformed the control group in total score gains (p = .002, r = .360). These results present a reasonable argument regarding of task interleaving inclusion viability within spaced repetition systems to promote a balanced and deeper learning of vocabulary alongside longer-term retention.