# Take-Over Time: A Cross-Cultural Study of Take-Over Responses in Highly Automated Driving
## 4 Discussion  
An important finding of the presented study is the notable differences in driving performance between the two locations, particularly in the take-over time and type of response to TOR. Participants in Seattle were significantly slower to respond to TOR (\(M=+1285\)) than Slovenian participants. Engagement in a secondary task (IVIS) at TOR also had an effect on take-over time (similar to [10]), while gender and age had no effect (cf. [13]). Distracted US participants had significantly longer response times to TOR (\(M=+1596\)) than distracted Slovenian participants. Within each site, mean adoption time was also longer for participants who engaged with IVIS, particularly for US participants (US: \(M=+1092\); SI: \(M=+402\)). Although the difference in mean acquisition time between the two locations was not significant for the non-distracted participants, it was large and consistent with the results of [7; 9]), with the non-distracted US participants having a longer mean acquisition time (\(M=+906\)) than the non-distracted Slovenian participants. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & & \multicolumn{3}{c}{**Task Completion Rate**} & \multicolumn{3}{c}{**NASA TLX Index**} \\ \hline
**Group 1** & **Group 2** & **Mean Diff** & \(\mathbf{p_{\text{corr}}}\) & **95\% CI** & **Mean Diff** & \(\mathbf{p_{\text{corr}}}\) & **95\% CI** \\ \hline A/C & contact & 0.40 & **0.001** & [0.2436, 0.5621] & \(-\)0.25 & **0.001** & [\(-\)0.3876, \(-\)0.111] \\ A/C & dial & 0.17 & **0.030** & [0.0103, 0.3288] & \(-\)0.12 & 0.114 & [\(-\)0.2598, 0.0168] \\ A/C & playlist & 0.39 & **0.001** & [0.2317, 0.5502] & \(-\)0.27 & **0.001** & [\(-\)0.4025, \(-\)0.1279] \\ A/C & radio & \(-\)0.08 & 0.67 & [\(-\)0.2377, 0.0847] & \(-\)0.08 & 0.546 & [\(-\)0.2113, 0.0615] \\ contact & dial & \(-\)0.23 & **0.001** & [\(-\)0.3916, \(-\)0.075] & 0.13 & 0.073 & [\(-\)0.0071, 0.2626] \\ contact & playlist & \(-\)0.01 & 0.9 & [\(-\)0.1702, 0.1464] & \(-\)0.02 & 0.9 & [\(-\)0.1497, 0.1179] \\ contact & radio & \(-\)0.48 & **0.001** & [\(-\)0.6396, \(-\)0.3191] & 0.17 & **0.004** & [0.0415, 0.3072] \\ dial & playlist & 0.22 & **0.002** & [0.0631, 0.3797] & \(-\)0.14 & **0.029** & [\(-\)0.2775, \(-\)0.0098] \\ dial & radio & \(-\)0.25 & **0.001** & [\(-\)0.4063, \(-\)0.0858] & 0.05 & 0.855 & [\(-\)0.0863, 0.1795] \\ playlist & radio & \(-\)0.47 & **0.001** & [\(-\)0.6277, \(-\)0.3072] & 0.19 & **0.001** & [0.0584, 0.3221] \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Comparison of the mean workload scores for IVIS tasks (Tukey’s HSD) 2. Left: objective workload measured by the task completion rate. Right: subjective workload measured by NASA TLX. Figure 2: The global NASA TLX workload scores for the IVIS tasks type (**left**) and the multiple comparisons plot of the completion rate per IVIS task type (**right**). The multiple comparisons plot shows the mean and the 95% confidence interval for each IVIS type. The significant difference from the reference group (in blue) is marked in red, whereas non-significant difference is marked in gray. The differences in response times between the two locations could be due to age differences, as half of the US participants were older than the Slovenian participants (see Table 1). However, as reported in the results (Section 3.2), there were no significant age-related effects on TOR, either between or within the two locations. For example, on the secondary task TOR, where age-related decline should be most pronounced, the distracted older US participants performed comparably to the younger US participants (acquisition time: \(M=3775\), \(SD=595\)). These results are supported by several studies that investigated age-related differences in vehicle take-over during automated driving [4; 5; 10; 13]. For example, in their meta-analysis of mean take-over times from 129 studies, [PERSON] et al. found that mean take-over times were shorter for participants who had no secondary tasks but found no consistent effect of age [5].