Do bilinguals perform better than monolinguals in foreign language vocabulary learning? A systematic review and meta-analysis

Aims and objectives: Bilingualism has often been related to advantages in learning foreign languages (FLs) as compared to monolingualism. Previous studies on FL vocabulary learning showed inconclusive results such as a disadvantage, no advantage, or an advantage of bilingualism. The objectives of the present paper are to investigate the extent to which bilingualism affects vocabulary learning in English as an FL (EFL) and the extent to which the learner's age and the nature of vocabulary tests moderate the potential bilingual advantage in learning EFL vocabulary.Methodology: We carried out a systematic review and a meta-analysis focusing on the difference in EFL vocabulary knowledge between monolingual and bilingual learners.Data and analysis: Thirty-seven effect sizes were extracted from 14 studies with 1,984 participants and were analysed by means of a random-effects meta-analysis. Q-statistics were used to analyse the moderator variables.Findings/conclusions: The results indicate a small bilingual advantage (g = .20) in EFL vocabulary knowledge. Neither the nature of vocabulary knowledge nor the learners' age was found to moderate this bilingual advantage. We conclude that bilingualism is associated with enhanced EFL vocabulary knowledge as compared to monolingualism and that this bilingual advantage is consistent in receptive vs. productive vocabulary knowledge and child vs. adolescent bilinguals.Originality: This study provides new insights into the bilingual advantage in FL vocabulary learning and contributes to our understanding of bilingual advantages in FL learning.Implications: Bilingualism fosters EFL vocabulary knowledge, regardless of the nature of vocabulary knowledge and the learner's age. Future meta-analyses should include more language background variables to account for the large diversity of bilingual populations.