The effect of task-induced involvement load on incidental vocabulary acquisition among ELT students

Vocabulary knowledge is at the heart of language learning as both comprehending and producing messages depend on knowing words. Second/foreign language learners need to acquire a great deal of vocabulary in a limited time to be successful in nearly all aspects of the target language Therefore, a large body of research has been devoted to investigating the best ways to help learners in their endeavour. In recent years, incidental acquisition of vocabulary has been found to be beneficial in expanding vocabulary knowledge. In this regard, how incidental vocabulary can be promoted is an intensely investigated subject. Incidental vocabulary acquisition through reading texts has been found to be facilitated by additional vocabulary tasks drawing the learners' attention to specific words. Therefore, designing the best vocabulary tasks has been an important issue for teachers. In order to address this concern, Laufer and Hulstijn (2001) proposed the Task-induced Involvement Load Hypothesis positing that the absence or presence of three components (evaluation, search and need) in a task determines the overall involvement load level induced by the task. Evaluation is related to learners' judgement on whether a specific word fits into a context. Search explains whether the meanings of words are searched by consulting dictionaries or other sources. Need is the motivational dimension of the construct and explains whether the drive to learn the word is extrinsically or intrinsically exposed. Using the framework of Laufer and Hulstijn (2001), this study aims to investigate the effect of four vocabulary tasks with varying distributions of evaluation, search and need components on incidental vocabulary gain and retention. The subjects were 139 first year ELT students from eight intact classes taking Academic Reading Course in the fall semester of 2015-2016. The subjects were assigned to four groups randomly: fill-in with glossary, fill-in by searching, retelling with glossary and retelling by searching. Two different texts were designed for four tasks. Each text contained 10 target words accompanied by reading comprehension questions. Prior to the implementation of the tasks, the participants' familiarity with the target words was tested through a pre-test which required providing the L1 equivalent or English explanations of the target words. The groups were to complete the reading comprehension tasks and the vocabulary tasks they were assigned to. The fill-in groups completed the gaps in the text with the target words, with or without glossary. The retelling groups wrote their own versions of the text by incorporating the target words, with or without glossary. Once the tasks were completed, the worksheets were collected and an unannounced post-test similar to the pre-test was administered. Similarly, two weeks later, an unannounced delayed post-test was conducted. For marking, each correct answer was counted as 1 and the incorrect ones as 0. Partially correct answers were awarded 0.5 point. The comparison of the groups on immediate and delayed post-tests using one-way ANOVAs showed that the tasks with higher level of involvement load yielded higher vocabulary gain and retention. However, the only significant differences were between retelling by searching and fill-in groups on the delayed post-test, which provided partial support for the Task-induced involvement load hypothesis. Keywords: incidental vocabulary acquisition, involvement load level, task-induced involvement load, vocabulary gain and retention, vocabulary tasks