Fostering incidental vocabulary uptake from audio-visual materials: The role of text comprehension

This research project explores various factors that may influence the rate of incidental foreign/second language (L2) vocabulary acquisition from audio-visual materials, with a special focus on procedures that enhance learners’ comprehension of these input materials. Informed by relevant theories and research findings in the fields of L2 listening comprehension and incidental vocabulary acquisition, I investigate the effects of having learners (a) view a TED Talks video twice rather than once, (b) sum up the content of the video before watching it a second time, (c) watch TED Talks videos on the same subject in order to increase familiarity with that subject, and (d) exchange summaries of TED Talks videos with peers so as to assist each other’s subsequent processing of those videos. As these interventions are all deemed to facilitate L2 listening comprehension, they are also expected to create favourable conditions for incidental vocabulary uptake to occur. The effects on incidental vocabulary acquisition of the above interventions were gauged in a series of classroom experiments with Vietnamese EFL learners. Although vocabulary uptake was generally far from spectacular, all of the tested procedures were found to result in statistically significant vocabulary gains. The insertion of the output tasks (i.e., the summary activities) was particularly useful. First, they helped to enhance the learners’ text comprehension. Second, they created opportunities for the learners to use newly met words and thus consolidate their knowledge of these lexical items. A thread through the experimental data is the strong association between the learners’ vocabulary uptake and their comprehension of the input content. The findings from this research project are consistent with several established notions, models and theories in the fields, including Ausubel’s Advance Organizer (1978), Hulstijn and Laufer’s Involvement Load Hypothesis (2001), Krashen’s Input Hypothesis (1985), Nation’s Vocabulary Generation (2013), Swain’s Output Hypothesis (2005), and Wittrock’s Model of Generative Teaching of Comprehension (1991). However, there are also findings that go beyond the core tenets of these, and that can further our understanding of how learners process new lexical items in meaning-focused input and output tasks. Regarding pedagogical implications, this research project confirms that fostering L2 listening comprehension creates favourable conditions for incidental vocabulary acquisition to happen, and that the aforementioned classroom procedures are facilitative in this regard, albeit to different degrees.