Pupil Dilation as an Index of Examinee's Cognitive Load in Answering a Mathematics Question: A Comparison Study of Different Approaches

Studies have demonstrated that task-evoked pupillary responses (TEPRs) can be adopted to measure the examinee's cognitive load. This study compared three approaches for the measurement of TEPRs, mean pupil diameter, mean pupil dilation, and mean percentage of pupil dilation, to determine the best-fit measuring method. The valid participants of this study were eight sixth-grade elementary students. The experimental materials used were two mathematics questions with differing difficulty. The generalized estimating equation (GEE) was employed to compare the goodness of fit of each approach. The results revealed that the measurement of TEPRs based on the mean percentage of pupil dilation measured every 4 s provided the best fit. The cognitive load that learners experienced affected their learning outcomes. The measurement of task-evoked pupillary responses is a useful way to understand examinees' cognitive load. We tried to identify the approaches (mean pupil diameter, mean pupil dilation, and mean percentage of pupil dilation) that provided a satisfactory good-of-fitness. Results showed that the approach of mean percentage of pupil dilation provided the best fit. The findings could help researchers to adopt a proper approach to understand examinees' cognitive load.