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.