Optimizing the usage of pupillary based indicators for cognitive workload

  • Benedict Fehringer University of Mannheim
Keywords: Eye tracking, Pupillometry, Index of Cognitive Activity (ICA), Index of Pupillary Activity (IPA), Cognitive Workload, R-Cube-Vis Test


The Index of Cognitive Activity (ICA) and its open-source alternative, the Index of Pupillary Activity (IPA), are pupillary-based indicators for cognitive workload and are independent of light changes. Both indicators were investigated regarding influences of cognitive demand, fatigue and inter-individual differences. In addition, the variability of pupil changes between both eyes (difference values) were compared with the usually calculated pupillary changes averaged over both eyes (mean values). Fifty-five participants performed a spatial thinking test, the R-Cube-Vis Test, with six distinct difficulty levels and a simple fixation task before and after the R-Cube-Vis Test. The distributions of the ICA and IPA were comparable. The ICA/IPA values were lower during the simple fixation tasks than during the cognitively demanding R-Cube-Vis Test. A fatigue effect was found only for the mean ICA values. The effects of both indicators were larger between difficulty levels of the test when inter-individual differences were controlled using z-standardization. The difference values seemed to control for fatigue and appeared to differentiate better between more demanding cognitive tasks than the mean values. The derived recommendations for the ICA/IPA values are beneficial to gain more insights in individual performance and behavior during, e.g., training and testing scenarios.

How to Cite
Fehringer, B. (2021). Optimizing the usage of pupillary based indicators for cognitive workload. Journal of Eye Movement Research, 14(2). https://doi.org/10.16910/jemr.14.2.4