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.

研究发现，主题兴趣可以增加保留的信息量并促进对文本的情感参与。在英语作为外语（EFL）的环境中，该结构与阅读理解相关，但很少有人关注它对附带词汇学习的影响。本研究通过评估主题兴趣对学习者附带词汇增益及其有效词典查找行为的影响，满足了通过 EFL 课堂​​阅读任务评估主题兴趣的研究需求。因此，96 名成人英语学习者通过访问在线词典阅读了两篇主题兴趣高或低的说明性文本。然后，进行了未宣布的接受性词汇后测，评估 24 个目标单词的学习和保留情况。研究结果显示，参与者在阅读有趣的文本时显着学习并保留了更多词汇，并且在这种情况下，在字典中查找的已学习和保留单词的百分比显着更高。该研究强调了动机因素在解释更好的认知表现和通过文本学习方面的相关性，以及文本中的主题兴趣是一个有价值的组成部分，可以在语言课堂环境中进行操纵以促进学习。