Effectiveness of L1 and pictures in multimedia conditions on learning second-language vocabulary: A meta-analysis

Multimedia inputs have been often used in second language (L2) vocabulary learning; however, the effective elements in multimedia inputs for L2 vocabulary learning have hardly been established. This study aims to identify the effective element(s) and further clarifies the meaning of different “domains” in multimedia L2 vocabulary learning. Considering that the learning target (L2 vocabulary) belongs to the verbal domain, the meaningful inputs are then constructed as within-domain (i.e. L1-based), cross-domain (i.e. Picture-based), and mixed-domain (i.e. L1+picture-based) learning conditions. The present study firstly conducted an omnibus analysis and then three meta-analyses: (a) within-domain vs. cross-domain (20 studies, 51 effect sizes), (b) within-domain vs. mixed-domain (21 studies, 55 effect sizes), and (c) cross-domain vs. mixed-domain (9 studies, 27 effect sizes), for a total of 2056 participants. Both immediate and available delayed tests were used as dependent variables. Four moderators were used to identify potential predictors. The results indicate that, at the immediate tests, the mixed-domain condition consistently outperforms the within-domain condition (g = 0.334, p < 0.001) and cross-domain condition (g = 0.350, p = 0.001) in facilitating L2 vocabulary learning. However, at the delayed tests, the advantageous effect of the mixed-domain condition only marginally outperformed the cross-domain condition (g = 0.271, p = 0.067). No significant difference was found between the within-domain and cross-domain conditions in L2 vocabulary learning. No significant moderator was detected at either the immediate tests or the delayed tests. These findings highlight the benefit of incorporating both L1 words and pictures into L2 vocabulary learning.