# Physiological Evaluation of User Experience in Unstable Automated Driving: A Comparative Study
## 3 Results
### Evaluation of User Response Under Extended Delay Conditions
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Categories**} & \multicolumn{4}{c}{**A.D(S)**} & \multicolumn{4}{c}{**A.D(C)**} \\ \cline{2-10}  & \multirow{2}{*}{**Mean**} & \multirow{2}{*}{**S.D.**} & \multicolumn{2}{c}{**Mean**} & \multirow{2}{*}{**Cohen’s d**} & \multirow{2}{*}{**Mean**} & \multirow{2}{*}{**S.D.**} & \multicolumn{2}{c}{**Mean**} \\  & & & & **(\(\rho\)-Value)*** & & & & **(\(\rho\)-Value)*** & \\ \hline \multicolumn{10}{c}{Self-rating of frustration (5 scale)} \\ \hline \multirow{5}{*}{\
\begin{tabular}{c} EMG (arm) \\ (0-1 n.u.) \\ \end{tabular} } & Seg. & \multirow{2}{*}{0.351} & \multirow{2}{*}{0.212} & \multirow{2}{*}{-} & \multirow{2}{*}{-} & \multirow{2}{*}{0.333} & \multirow{2}{*}{0.142} & \multirow{2}{*}{-} & \multirow{2}{*}{-} \\  & R-1 & & & & & & & \\ \cline{2-10}  & Seg. & R-2 & 0.360 & 0.204 & 0.009 (0.800) & 0.048 & 0.341 & 0.174 & 0.007 (0.857) & 0.034 \\ \cline{2-10}  & Seg. & R-3 & 0.339 & 0.213 & \(-\)0.012 (0.796) & 0.048 & 0.355 & 0.150 & 0.022 (0.516) & 0.122 \\ \cline{2-10}  & Seg. & R-4 & 0.336 & 0.202 & \(-\)0.016 (0.632) & 0.090 & 0.338 & 0.151 & 0.004 (0.897) & 0.024 \\ \cline{2-10}  & Seg. & R-5 & 0.345 & 0.206 & \(-\)0.006 (0.887) & 0.027 & - & - & - & - \\ \cline{2-10}  & Seg. & R-6 & 0.345 & 0.187 & \(-\)0.006 (0.901) & 0.023 & - & - & - & - \\ \hline \multirow{5}{*}{
\begin{tabular}{c} EMG (leg) \\ (0-1 n.u.) \\ \end{tabular} } & Seg. & \multirow{2}{*}{0.350} & \multirow{2}{*}{0.180} & \multirow{2}{*}{-} & \multirow{2}{*}{-} & \multirow{2}{*}{0.345} & \multirow{2}{*}{0.185} & \multirow{2}{*}{-} & \multirow{2}{*}{-} & \multirow{2}{*}{-} \\  & R-1 & & & & & & & \\ \cline{2-10}  & Seg. & R-2 & 0.366 & 0.203 & 0.016 (0.668) & 0.080 & 0.373 & 0.173 & 0.027 (0.441) & 0.145 \\ \cline{2-10}  & Seg. & R-3 & 0.387 & 0.223 & 0.037 (0.421) & 0.152 & 0.381 & 0.147 & 0.036 (0.257) & 0.215 \\ \cline{2-10}  & Seg. & R-4 & 0.424 & 0.228 & 0.074 (0.042)** & 0.396 & 0.370 & 0.182 & 0.025 (0.485) & 0.131 \\ \cline{2-10}  & Seg. & R-5 & 0.386 & 0.227 & 0.036 (0.373) & 0.168 & - & - & - & - \\ \cline{2-10}  & Seg. & R-6 & 0.377 & 0.208 & 0.027 (0.562) & 0.109 & - & - & - & - \\ \hline \hline \end{tabular}  
* Numerical difference between the current segmentation and the first segmentation. ** \(\rho<0.05\).  
\end{table} 
Table 6: Results of user frustration ratings and physiological change analysis at roundabout segmentations (\(n=30\)). value was also approximately 0.45, confirming that the effect size was moderate. In contrast, in A.D(C), EMG measurements at Seg. M-2 showed slight decreases in both arm and leg measurements compared to Seg. M-1. This suggests that the continuous driving behaviors of controlling speed by driving slowly to ensure adequate gaps in the acceleration lane helped to reduce participant frustration. Figure 8: Changes in EMG (arm) activation values of participants according to A.D styles at different segmentations of merging. Figure 6: Changes in EMG (leg) activation values of participants according to A.D styles at different segmentations of roundabout. Figure 7: EMG (leg) activation values per roundabout segmentation. As shown in Table 8, the evaluation results for the unsignalized intersection situations revealed that participants reported frustration levels of 3.06 points for A.D(S) and 1.56 points for A.D(C), showing similar trends to the other segments. Significant physiological changes in this segmentation were observed primarily in the EMG (leg) measures. As shown in Figures 10 and 11, in the A.D(S) scenario, significant measurement differences began to occur from the moment of stopping at the stop line (Seg. U-2) compared to the moment before entering the unsignalized intersection (Seg. U-1). Specifically, the EMG (leg) measurements showed a maximum increase of 0.095 at Seg. U-3 compared to Seg. U-1, which is interpreted as the frustration of waiting affecting the EMG (leg) measurement changes. The Cohen's d value for the average difference is approximately 0.55, which