Effects of dual- and single-language exposure on children’s word learning: Experimentally testing the role of competition

This study investigated the role of dual- and single-language input in bilingual children’s word learning. In Experiment 1, 26 Spanish–English bilingual children aged 4 and 5 years (9 girls; 73% Latino; 65% White) learned novel words in single- and dual-language conditions. In the single-language condition, children learned English-like labels for novel objects. In the dual-language condition, the same children learned Spanish- and English-like labels for a different set of objects; all labels were produced by the same bilingual speaker, creating competition between the two languages. A second group of bilingual children (N = 25; 14 girls; 72% Latino; 40% White) participated in Experiment 2, which tested whether tagging language by speaker in the dual-language condition (mimicking the one person–one language input strategy) would influence performance. In both experiments, participants learned novel English words above chance (ps < .05) in both conditions, with better performance in the single-language condition. These results indicate an advantage for single-language learning contexts, but the theoretical roots and the practical value of this advantage are unclear.