Mapping the Multimodal Ecology of Video-Based Incidental Vocabulary Acquisition: A Systematic Review with Pedagogical Insights

Abstract

This study presents a PRISMA-guided systematic review synthesizing empirical research on video-based incidental English vocabulary learning in second and foreign language contexts. Using the Web of Science Core Collection as the sole database, 743 records were initially retrieved, with 103 studies retained following title–abstract screening, full-text eligibility assessment, and application of predefined inclusion criteria. The review aimed to move beyond modality comparisons by mapping the multimodal ecology through which vocabulary learning unfolds in audiovisual environments. Specifically, it examined how video-based multimodality has been theorized, which cognitive, affective, and behavioral processes mediate lexical uptake and retention, how incidental vocabulary learning has been operationalized and measured, and what pedagogical principles emerge from the accumulated evidence. The synthesis indicates that vocabulary gains from video viewing are not attributable to modality per se but to the interaction of three mechanism families: dual-channel representational enrichment, cognitive load calibration, and attention- and engagement-driven processes such as noticing, self-regulation, repetition, and task-induced elaboration. The review further demonstrates that conclusions in this domain are strongly shaped by methodological choices, particularly outcome constructs and testing timing, with recognition-based measures privileging noticing effects and delayed or productive measures foregrounding consolidation processes. Pedagogical implications highlight the need for purpose-driven captioning and glossing configurations, calibrated multimodal density, and designs that support learner control and repeated exposure. Overall, the study advances a process-oriented framework for understanding and designing video-based vocabulary learning environments.