## 3 Results  
### Conventional Pupil-Size Measures  
Looking at the average pupil-size responses, two trends could be observed. First, a very small pupil size at the start of each answer relative to the participant's average pupil size. This was likely caused by the pupillary light reflex in response to the difference in screen luminance from a screen on which participants had read a question to an image of the interviewee while she answered the question. Second, we can see a rise in average pupil size between answers to baseline questions (Questions 8 to 18) and answers to questions differing in emotional content (between groups; Figure 1). This increase in pupil diameter from the baseline to the manipulation--that is, the interviewee's emotionally more or less negative responses, can be found in every single participant. When comparing the pupillary changes between groups, the largest average change between the baseline and the manipulations occurred in the high-mental-workload conditions (NEUH: with a delta of 3.134 pixels; NEGH: with a delta of 2.786 pixels), followed by participants in the low-workload/negative-content group (NEGL: delta of 1.260 pixels), and lastly the participants in the NEUL group (delta of 0.607 pixels). Although Figure 1 shows that participants in the NEGH Group have had the smallest pupil diameter of all groups, this only means that the average pupil diameter in this group was smaller in the baseline condition to begin with. Figure 2 underlines the difference in pupil diameter change between the baseline and the manipulation in all groups. While participants in the  
Figure 1: Average pupil diameter in pixels as a function of the answer, separately for different groups (NEUL: neutral content/low load; NEUH: neutral content/high load; NEGL: negative content/low load; NEGH: negative content/high load). The two dotted lines in the colors of each group show the corresponding condition’s difference in average pupil size between baseline questions (bottom line) and manipulation questions (top line). NEUL group showed the smallest increase in pupil diameter, when the baseline average is subtracted from the average during manipulation, participants in the NEUH group show the biggest increase. Participants in the NEGL group as well as those in the NEGH group showed a similar difference, suggesting that the increase in pupil size due to the emotional content quantitatively limited the influence of mental workload on pupil size. An ANOVA yielded a significant main effect of workload, \(F(1,\,35)=6.95,\,p=0.013\), \(\eta^{2}=0.17\), but the influence of Emotion, \(F(1,\,35)=0.03\), \(p=0.858\), \(\eta^{2}=0.002\), and the interaction, \(F(1,\,35)=0.32\), \(p=0.576\), \(\eta^{2}=0.01\), were not significant. A post hoc \(t\)-test between low- (\(M=0.49\), \(SD=3.14\)) and high-workload conditions (\(M=3.53\), \(SD=3.68\)) showed significantly smaller pupillary changes in low-workload conditions compared to high-workload conditions, \(t(35)=-2.667\), \(p=0.012\), \(\eta^{2}=0.89\). Further calculations showed that the main effect of workload was due to a faster average shrinking of pupil sizes of participants in the low-workload conditions over the course of the interview compared to participants in the high-workload group. A point of divergence, from which the pupil size of the low-workload groups significantly differed from those of the high-workload groups, is the 27 th question in the interview: An ANOVA using only questions after the 27 th question yielded a very similar pattern of results as the initial ANOVA, Workload: \(F(1,\,35)=7.73\), \(p=0.009\), Emotion: \(F(1,\,35)=0.05\), \(p=0.818\), and Workload \(\times\) Emotion: \(F(1,\,35)=0.39\), \(p=0.537\).