The present study investigated whether word learning and retention in a second language are contingent upon a task's involvement load, i.e., the amount of need, search, and evaluation the task imposes. Laufer and Hulstijn (2001) contend that tasks with higher degrees of these three components induce higher involvement load, and are, therefore, more effective for word learning. To test this claim, 64 Iranian intermediate EFL learners were selected based on their performance on the Preliminary English Test (PET). The participants were randomly assigned to two equal groups. Each group completed different vocabulary learning tasks that varied in the amount of involvement they induced. The tasks were jigsaw task (Group A) and information gap task (Group B). During the ten treatment sessions, recall and retention of the 100 unfamiliar target words were tested through immediate and delayed posttest. Data were analyzed using repeated measure ANOVA. The results indicated that learners benefited more from jigsaw task with higher involvement load. This study supported the Involvement Load Hypothesis, suggesting that higher involvement induced by the task resulted in more effective recall; however, no significant difference was observed between the two tasks in the retention of the unknown words.
