Topic interest increases L2 incidental vocabulary learning and effective dictionary look-up behaviour

Topic interest has been found to increase the amount of information retained and facilitate emotional engagement with a text. In English as a Foreign Language (EFL) settings, the construct has been related to reading comprehension, but little attention has been given to its effect on incidental vocabulary learning. The present study addresses the call for research assessing topic interest through EFL classroom reading tasks by evaluating the effect of topic interest on learners’ incidental vocabulary gains and their effective dictionary look-up behaviour. Thus, 96 adult EFL learners read two expository texts with either a high or a low level of topic interest with access to an online dictionary. Then, unannounced receptive vocabulary post-tests assessing learning and retention of 24 target words were administered. Findings revealed that participants significantly learned and retained more vocabulary when reading the interesting text, and that the percentage of learned and retained words that were looked up in the dictionary was significantly higher in that condition. The study highlights the relevance of motivational factors in explaining better cognitive performance and learning through texts, and the idea that topic interest from text is a valuable component that can be manipulated in language classroom settings to advance learning.