Designing appropriate materials and activities to enhance vocabulary learning is one of the primary goals of language courses. Among the claims about efficient pedagogical tasks is the Involvement Load Hypothesis (Laufer & Hulstijn, 2001) according to which vocabulary development is contingent on the amount of cognitive process a task involves. Building on the previous research on this hypothesis, this study seeks to explore the extent to which three post-listening tasks of different involvement loads along with single-versus dual-mode glosses affect receptive and productive vocabulary learning of advanced English as a foreign language (EFL) learners. The participants (n = 204) listened to an expository text while twenty lexical items were presented through text-only or text-plus-picture glosses. Subsequently, they were assigned to one of the task type groups (sentence writing, gap-fill, and paragraph writing). Paribakht and Wesche’s (1997) Vocabulary Knowledge Scale was employed as the pre and post-tests. The results pointed to the efficacy of dual-mode over single-mode glosses concerning both receptive and productive vocabulary learning. The sentence writing task produced the highest scores in the vocabulary tests, whereas the gap-fill and paragraph writing tasks did not significantly differ. Hence, the results only partially confirmed the Involvement Load Hypothesis. The current study corroborates other studies verifying the modality effect on vocabulary learning and suggests that task type is a significant factor in EFL vocabulary learning.
