This article reports on the findings of a study that investigated the impact of manipulating task performance conditions on listening task performance by learners of English as a foreign language (EFL). The study was designed to explore the effects of changing complexity dimensions on listening task performance and to achieve two aims: to see how listening comprehension task performance was affected and to investigate possible overlaps between EFL learners’ perceptions of task difficulty and hypothesized task complexity. A purposive sample of 54 first-year EFL learners randomly assigned to two parallel conversation classes in an English department of a major public university participated in the study and performed listening tasks in a language lab. The instruments used for data collection were seven tasks taken from a TOEFL Test Preparation Kit, each followed by listening comprehension questions and an item on the participants’ personal perception of the difficulty of the task. During counter-balanced administrations, the tasks were manipulated for one of the four dimensions of task difficulty (adequacy, immediacy, perspective, and prior knowledge). The resulting data included the participants’ perception of difficulty as well as their performance scores under less complex and more complex conditions. One-sample T-test and correlation analyses of the data revealed that for all of the four complexity dimensions, the hypothesized less complex task condition led to better learner performance. The correlation between learner-assigned difficulty score for the task at hand and theoretical task complexity level was significant only for the immediacy dimension (r=-0.67, p<.05). The results offer support for task complexity frameworks, raise doubts about learners’ perceptions of tasks, and imply possibilities for task manipulation in language learning contexts.
