Optimizing the usage of pupillary based indicators for cognitiveworkload

摘要

The Index of Cognitive Activity (ICA) and its open-source alternative, the Indexof Pupillary Activity (IPA), are pupillary-based indicators for cognitiveworkload and are independent of light changes. Both indicators were investigatedregarding influences of cognitive demand, fatigue and inter-individualdifferences. In addition, the variability of pupil changes between both eyes(difference values) were compared with the usually calculated pupillary changesaveraged over both eyes (mean values). Fifty-five participants performed aspatial thinking test, the R-Cube-Vis Test, with six distinct difficulty levelsand a simple fixation task before and after the R-Cube-Vis Test. Thedistributions of the ICA and IPA were comparable. The ICA/IPA values were lowerduring the simple fixation tasks than during the cognitively demandingR-Cube-Vis Test. A fatigue effect was found only for the mean ICA values. Theeffects of both indicators were larger between difficulty levels of the testwhen inter-individual differences were controlled using z-standardization. Thedifference values seemed to control for fatigue and appeared to differentiatebetter between more demanding cognitive tasks than the mean values. The derivedrecommendations for the ICA/IPA values are beneficial to gain more insights inindividual performance and behavior during, e.g., training and testingscenarios.