Second and foreign language vocabulary learning through digital reading: a meta-analysis

Digital reading facilitates L2 development by allowing anytime-anywhere learning with various digital resources. Although there has been increasing research exploring the role of digital reading on L2 vocabulary learning, synthesized evidence regarding the overall facilitating power of digital reading is still lacking. This meta-analysis aggregates 21 important empirical studies published within the last 20 years and indexed in scholarly recognized databases, so as to provide a comprehensive panoramic assessment of how effectively digital reading has enhanced second and foreign language vocabulary acquisition with diversified learner backgrounds and learning environments. A total of 77 effect sizes were yielded across different studies, and random-effect modeling was employed for analyzing the study-level heterogeneity and sub-group variability. Results demonstrate that digital reading had an overall significant effect (dimmediate = 1.45, p < .01; ddeleayed = 2.98, p < .01) on L2 vocabulary learning of between-subject studies. For within-subject studies, digital reading was found to have an upper-medium (d = 1.39, p < .01) and medium (d = .86, p < .01) effect on immediate and delayed L2 vocabulary post-tests. Moderating factor analysis results show that L2 proficiency, vocabulary test formats, and digital resources could robustly explain the variance of effect sizes. The findings have strong pedagogical implications on the effective design for digital reading tasks, including the development of adaptive learning algorithms and personalized lexical glosses. Recommendations for future research in the field are provided by pinpointing where to improve in terms of experimental design and the focus of the learner group.