Limitations and future directions
Participants of this study were English as second language learners in Hong Kong and thus the results may not be applicable to native English speakers or students in another region of the world. Future work may examine whether the current findings can be found among native English speakers and whether the effect of BGM is language-specific. This study is limited to the reading task in which students have autonomy to self-regulate their learning processes (i.e., they had unlimited time to read) with their self-selected music. It does not include music composed for specific learning tasks or strategically chosen by teachers. Our findings may not be generalized to other types of tasks or assessment episodes (e.g., viewing instructional videos, writing essays, solving math puzzles). Moreover, the reading materials were limited to passages in standard tests. While standard tests can be more accurate in measuring passage comprehension accuracy, reading materials in the reality are diverse including novels, poems etc, which can be considered in future studies. Besides, during the experiment, the researchers were aware of the conditions to which the participants were assigned to. Future work will improve the experiment design to maintain strict blinding. Last but not least, we may not have sufficient power to test for group difference on some variables (e.g., observed power for passage comprehension accuracy is 0.327). Future studies can examine the research questions with a larger sample size to better reveal the effect of music on reading (e.g., a sample size of 340 would be needed to find a statistically significant difference for two evenly divided groups in an independent sample t-test, with the observed effect size d = .305, 0.05 given alpha, 0.8 given power, and 2 tails).