2.4.2. Pupillometry
Pupil diameter was measured during the MIST task and Ocular tasks. When using video-based eye trackers, pupil diameter distorts as a consequence of the position of the eyes. Therefore, this study excluded the data that fell outside of a two-degree visual angle square that was centered on the fixation point as well as the samples that fell during blink and saccade events. In the MIST task, for each trial and each participant, the baseline pupil diameter was determined as the mean pupil diameter measured 300 ms before the mental arithmetic test onset. To account for individual variability in pupil size, the baseline pupil size was deducted from the mean pupil diameter during each experiment (Langer et al., 2022). The area under the curve concerning increase (AUCi, see Kuchinke et al., 2011) following the arithmetic test onset was determined as a measure of the total pupillary increase in response to the presentation of the mental arithmetic (Langer et al., 2020). Pupil dilations were averaged across each trial. In Ocular tasks, the individual pupil diameter was calculated by averaging during the 3 min measurement period.