Impact of Formulaic Language on Vocabulary Acquisition in Bilingual Students in Lagos State, Nigeria

Formulaic language plays an important role in reducing cognitive load, improving fluency, and enhancing vocabulary retention. This study investigates the impact of formulaic language on vocabulary acquisition, retention, and usage among Yoruba-English bilingual students in Lagos State, Nigeria. Despite its significance, limited research exists on its impact in bilingual contexts, particularly in socioeconomically diverse settings like Lagos. Using a quantitative research design, 100 participants from low-cost private schools and government-funded public schools were exposed to 30 formulaic expressions over three weeks. Vocabulary retention and usage were assessed through pre-tests, post-tests, and delayed tests. Findings reveal that exposure to formulaic expressions significantly improved vocabulary retention in both groups, with low-cost private school students outperforming their public-school counterparts. Retention remained high (over 85%) in both groups during the delayed test phase, underscoring the effectiveness of formulaic language in long-term memory. However, the ability to use formulaic expressions in speaking and writing tasks lagged behind retention scores, particularly among public-school students. This highlights the need for more interactional practice during instruction. The study also examined the influence of cultural and contextual peculiarities on the comprehension and application of formulaic expressions. Results indicate that students with access to higher-quality instruction and culturally contextualised materials demonstrated better pragmatic competence and contextual appropriateness. These findings emphasize the role of formulaic language in bridging linguistic and cultural gaps. Therefore, this research highlights the need for bilingual learners to receive explicit instruction in formulaic language.