The impact of topic interest, L2 proficiency, and gender on L2 incidental vocabulary acquisition through reading

Second language (L2) research has explored various factors promoting vocabulary learning through reading due to its critical role in L2 language and literacy development. One neglected factor is topic interest—interest learners have in the texts they read—a motivational factor purported to contribute to higher involvement with reading tasks and, in turn, incidental vocabulary learning. The present study explored this gap and expanded on the motivational factors considered in the involvement load hypothesis (Laufer & Hulstijn, 2001). Using a repeated-measures design with 135 Korean EFL students, the study investigated the effects of topic interest, alongside L2 proficiency and gender, on vocabulary learning through reading. Materials included two brief expository passages (one of low, and one of high interest). Control variables included topic familiarity (both highly-familiar topics) and target-word difficulty (a balanced ratio across passages between nouns, verbs, and adjectives of matching word length and concreteness). The study was conducted over several sessions. Students first took a pretest on 30 target words. Two weeks later, students read both passages and took immediate vocabulary posttests (word-form recognition, translation recognition, and translation production). Four weeks later, similar delayed posttests were administered. The data were analyzed using a repeated-measures MANCOVA and GEE. Results revealed significant positive effects of topic interest and L2 proficiency, whereby learners gained significantly more new words from the high-interest topic text and more gains were associated with higher proficiency. A nonsignificant interaction between topic interest and L2 proficiency suggested that the effect of topic interest was consistent for higher and lower proficiency learners. A significant interaction between gender and topic interest revealed that boys acquired fewer words than girls on the low-interest topic text. These results were maintained over time. By highlighting the neglected variable of topic interest, the results expand upon the involvement load hypothesis in considering both motivational and cognitive factors in incidental vocabulary learning. They also advance language educators’ understanding of the facilitative role of topic interest in students’ vocabulary growth. This study’s pedagogical insights on how gender is connected to topic selection will aid teachers in enhancing individual learners’ successful L2 reading and vocabulary development.