## 4 Discussion  
In our study, even though the participants were told that they were riding in a highly automated vehicle and that automation could handle various risky events on the road, there were still a few (\(n\) = 8) who took over the vehicle during the driving event due to fear that the automation would not handle the hazard well. The behavior of unanticipated takeover can be viewed as a form of non-reliance, by definition. And reliance was often correlated with trust [17; 37; 38] or was even a result of trust in the automation [43]. In this study, driver takeover was clearly an undesirable result of mistrust, albeit infrequent, and this behavior should be avoided. In comparison, the other dependent variables, even if they were skewed to the side of distrust, do not have much of a negative impact on human-vehicle collaboration. Moreover, in line with our expectations, the participants' NDRT performance while driving was generally high, their attention was more focused on the center control display, and the trust scores after driving were relatively high. While participants' attitudes and behaviors to the ADSs of this experiment generally tended to be on the side of trust and reliance, the effects of SAT, scenario urgency, and driving stage varied and were somewhat subtle. In this study, the effects of the SAT on trust and reliance were generally consistent with our expectations, and these results partially supported H2, which was the focus of the study. For example, under the SAT level 1 + 3 and SAT level 1 + 2 + 3 conditions, participants paid more attention to the NDRT, exhibited a higher NDRT performance, and showed an increased trust in the ADS compared to the results for the SAT level 1 condition. This finding is consistent with the view of many previous studies that the transparency in terms of uncertain information (i.e., reasoning information for SAT level 2 and projection information for level 3) improved both trust and task performance [20; 44; 45]. The effects also indicated the two high-level SAT conditions were not significantly different in regards to the dependent variables of takeover performance, NDRT performance, eye-tracking metrics, and subjective trust. These results are inconsistent with those obtained in some previous studies involving SAT, which found that the participants' trust or performance increased as the level of transparency increased [20; 24; 27; 28]. There may be several explanations for this difference. The most straightforward explanation is that the interface designs in the SAT level 1 + 3 and SAT level 1 + 2 + 3 conditions were quite similar because of the simplicity of the driving event employed in the experiment. As mentioned by several participants, for the two high-level SAT groups, to make a decision, they did not pay attention to what particular information the interface provided, but only to the driving scenarios. To speculate further on differences regarding scenario simplicity, follow-up efforts should conduct more targeted testing. Another possible explanation for the results obtained in the current study is that previous experimental studies involving SAT model have focused only on the sequential stacking of transparency levels and not on the combination of SAT level 1 and level 3 conditions [24; 28; 32]. Instead, this study investigated the role of SAT level 1 + 3 in supporting driver trust and reliance and proposed the hypothesis that SAT level 1 + 3 maybe superior to other levels of transparency, especially in high-urgency scenarios, based on [PERSON]'s statement that humans may only need to know the system's actions and the projection to make a sufficiently informed decision in time-sensitive situations [25]. In the experiment, the results regarding workload did not support H4, but the following insights may explain this result.