Rethinking Bilingual Enhancement Effects in Associative Learning of Foreign Language Vocabulary: The Role of Proficiency in the Mediating Language

The present study investigated claims that learning vocabulary in an unfamiliar language is more efficient in bilinguals than in monolinguals and the possible effects of language proficiency and dominance. In Experiment 1, monolingual ( = 48) and bilingual participants ( = 96) learned Japanese words paired with English translations and completed cued-recall and associative-recognition tests. Accuracy did not differ across monolingual and bilingual or language dominance groups. Nevertheless, in bilinguals, higher English proficiency was associated with higher accuracy. In Experiment 2, Japanese-English bilinguals ( = 40) learned Spanish-Japanese word pairs, and higher Japanese proficiency was associated with higher accuracy. Associative strategies were reported at a higher rate in bilingual than in monolingual participants but were not associated with more accurate performance. Careful comparisons of the present and previous results support the conclusion that higher proficiency in the language through which bilinguals learn foreign vocabulary enhances associative memory, but bilingualism itself does not.