## 5 Limitations  
Our cognitive-load manipulation was relatively weak. This was not only reflected in similar performance (accuracy) levels in both cognitive-load conditions--high- and low-load conditions but also in participants' subjective self-assessments of cognitive load, which were the same in high- and low-load conditions. In contrast, to our surprise, participants subjectively felt and reported more cognitive and physical demands in negative than neutral conditions; a subjective rating that was not reflected in our pupil-size measures. Another important limitation concerns doubts about the success of our manipulation of emotional content. Although participants subjectively felt more frustrated and generally reported more negative feelings under negative than under neutral conditions, some participants did not believe in the veridicality of the answers of the confederate/interviewee. This implies that the manipulation of the participants' emotions was probably relatively weak. This problem was potentially exacerbated by the semi-controlled nature of our task as we will discuss next. The current study used semi-controlled conditions: On the one hand, control itself was, thus, partly limited. For example, emotional content manipulations were confounded with the different exact words or phrases used by the interviewee. Another example is that the exact behavior of the confederate/interviewee varied slightly from participant to participant (e.g., in the form of the exact length of the verbal answer or the exact strength of a facial expression), even within groups, thereby creating additional and unwanted noise in the data. On the other hand, conducting interviews in front of a computer screen allowed some degree of control (e.g., easier calibration of the eye tracker) but might have compromised the perception of nonverbal facial expressions and could have mitigated emotional responses to the stimulus. In this way, control means that our conditions were not entirely the same as those encountered in the field, and our study is, thus, only a step in the direction of closing the gap between laboratory and field conditions. Another potential limitation concerns insufficient power. It is well known that insufficient power can lead to oversights of existing effects that simply do not turn out to be significant. However, it is probably still less well known that a lack of sufficient power can also compromise the replicability of significant findings [53]. In this respect, our study could also stand improvement in terms of a larger sample besides the aforementioned improvements in terms of the manipulations. We used a measure of cognitive load that disregards the impact of saccades on pupil dilations. Our research is, thus, silent on how to incorporate saccade-elicited influences on pupil size into pupillary load measures. We think rightly so, as long as it is unclear if and how saccades are related to cognitive load. On the one hand, temporal attention and, thus, a particular cognitive-load factor might temporarily decrease saccade frequencies and related pupillary changes (cf. [54]). On the other hand, spatial attention and, thus, a different factor affecting cognitive load might be accompanied by (micro-)saccades and their associated pupillary changes (e.g., [55; 56]). However, we agree that future research would benefit from discriminating between saccade-related pupillary changes and other load-elicited pupil responses in different tasks to understand when saccade-related pupil changes are true reflections of cognitive load and when they are better filtered out as not related to load or other difficulty related measures (cf. [57]). Since our interview was conducted in front of a computer screen, generalizability to a face-to-face scenario is not granted. Not only might more eye movements under 3D conditions lead to less accurate pupil-size data.