Knowledge of English Affixes in Thai EFL Learners of Science and Language Programs

This study investigated the knowledge of affixes on vocabulary development among English as a Foreign Language (EFL) learners, focusing on the differentiation between students studying science and those studying the language. Affix knowledge, encompassing both prefixes and suffixes, is essential for expanding word family knowledge, serving as a cognitive bridge to proliferate word family members. To explore this, 111 secondary school students from a semi-urban Thai school, split into 53 science and 58 language program students, were assessed through receptive and productive affix knowledge tests. The findings reveal that science program students outperformed their language counterparts in receptive affix knowledge tests. Additionally, results indicated a learning continuum in affix acquisition, with students showing better average performance on receptive tests compared to more complex productive tasks. Notably, affix knowledge concerning prefixes was superior to that of suffixes across both test types. Moreover, the correlational analysis revealed a medium to strong relationship between English affix knowledge and vocabulary knowledge. The findings also suggest that suffix knowledge has a greater impact on productive vocabulary than on receptive vocabulary. Regression analysis supports the correlation results, highlighting that a deeper understanding of affixes is linked to stronger vocabulary knowledge in both comprehension and usage. These results suggest a structured progression in affix learning, from recognition to production, and underline the significance of affix knowledge in vocabulary expansion for EFL learners. The study emphasizes the need for further research into the mechanisms of affix acquisition and its role in language learning curricula.