## 4 Discussion
The differences in participants' workloads were small between the SAT level 1 and SAT level 1 + 3 conditions, and the participants showed the highest workload under the SAT level 1 + 2 + 3 condition, although the difference was not statistically significant. As [PERSON] et al. discovered, the users did not enjoy the increase in task workload, despite the utility of the added information [27]. One participant in the SAT level 1 + 2 + 3 group also noted that the interface looked a little messy, so he preferred to look at the driving scenarios to determine whether the road was dangerous and if the vehicle needed to be taken over. From this evidence, we deduced that additional transparency information does enhance the interpretability or increase the user's understanding of the system, but in a risky, time-critical task, such as driving, too much information may be detrimental to task performance and user experience. This interpretation is supported by the findings of [PERSON] and [PERSON], who found a decrease in perceived usability with increased transparency information and workload, despite no difference in performance [46]. Therefore, if the road condition and workload are the sources of driver reliance and trust, one solution may be to utilize in-vehicle interfaces to enhance trust and human-vehicle collaboration, based on road conditions and physiological indicators of workload. To fully examine the effects of SAT on driver reliance on the ADS, this study also investigated participants' visual attention and NDRT performance before and after viewing the SAT interface. The results indicated that the users did have a tendency to shift their attention from the driving scenario to the center control display after viewing the SAT interface, but this shift was not statistically significant in terms of eye movement metrics and NDRT performance. These results do not support H1, but still warrant further investigation in the future in regards to more realistic hazardous events, as well as to higher fidelity simulated driving. In addition to the impact of the SAT on driver trust and reliance, this study also focused on differences in the SAT across various levels of driving scenario urgency. At the time of design, the two driving scenarios used in this study were manipulated according to the distance between the participant's vehicle and the hazard at the beginning of the event, and the urgency of the two scenarios was progressive. However, the results indicated that the effects of scenario urgency on all dependent variables were not statistically significant, which did not support H3. One possible reason for this is that, as discussed above, the driving event was too simple, so participants were able to quickly understand the hazard in both the high- and low-urgency scenarios. Another possibility is that the experimental design did not sufficiently differentiate the level of urgency in the scenarios, or that the high-urgency scenarios were not designed to be adequately time-sensitive. As previously suggested, an acceptable TORIt was about 6 s when engaged in a NDRT [35]; presenting the SAT interface 6 s earlier in the experiment did prompt the participants to feel adequate urgency. In their interviews, some of the participants also mentioned that there was little difference between the two driving trials. If the second statement is true, then it makes sense that the advantages of receiving SAT level 1 + 3 information under time-sensitive contexts were not fully realized under this study design. Nonetheless, we were able to observe some differences among SAT conditions in scenarios with different levels of urgency. For example, the participants showed the highest correctness of NDRT and paid the most attention to the central control display in the combination of SAT level 1 + 3* condition, or low urgency*, stage 2.