Optimizing the Effectiveness of Captioned Viewing for Incidental Second Language Vocabulary Learning: The Effects of Repeated Viewing and Reading Fluency

Abstract This study examined the effects of repeated viewing and reading fluency on incidental second language vocabulary acquisition through captioned video exposure. A total of 149 Japanese EFL learners watched a short animation with or without captions, varying in the number of repetitions (once, twice, or three times). A pre‐post‐delayed test design was employed to measure learning gains for 20 target words using written meaning recognition and meaning recall tests. A self‐paced, sentence‐by‐sentence reading test was also administered to assess reading fluency. Results from the immediate meaning recognition and meaning recall test revealed a positive effect of captioning. On the other hand, although repeated viewing did not have a clear influence on vocabulary acquisition, the results of immediate meaning recognition suggested that two or more captioned viewings as well as three viewings without captions may be more beneficial. The delayed posttests showed different patterns, suggesting that knowledge retention is strongly influenced by learner‐related variables (e.g., prior vocabulary knowledge) and the frequency of target word occurrences. Contrary to our prediction, reading fluency did not emerge as a significant variable in any of the test results. These findings are discussed in relation to potential strategies for optimizing captioned video use in language learning and teaching.