Pupillary diameter monitoring has been proven successful at the objectively measuring cognitive load that might otherwise be unobservable. This paper compares three different algorithms for measuring cognitive load using commodity cameras. We compare the performance of modified starburst algorithm (from previous work) and propose two new algorithms: 2 Level Snakuscules and a convolutional neural network which we call PupilNet. In a user study with eleven participants, our comparisons show PupilNet outperforms other algorithms in measuring pupil dilation, is robust to various lighting conditions and robust to different eye colors. We show that the difference between PupilNet and a gold standard head-mounted gaze tracker varies only from -2.6% to 2.8%. Finally, we also show that PupilNet gives similar conclusions about cognitive load during a longer duration typing task.
Wangwiwattana, C., Ding, X., & Larson, E. (2015). Proceedings of the ACM on Interactive, Mobile, Wearable and Ubiquitous Technologies (IMWUT Dec, 2017)