## 3 Results  
### The Most Frequently Performed Tasks Across All Cars  
Based on all sixty trips (i.e., the trips with the familiar and unfamiliar car grouped together), direction indicators are the most frequently used controls, followed by adjusting the front windshield wipers' speed and adjusting the radio volume. On average, the direction indicators were used 66.4 times per hour. A repeated-measures ANOVA revealed that this is statistically significantly higher than the average use frequency for any of the other tasks (\(p<0.001\)). Figure 1 shows the average frequency of the ten most frequently performed tasks over all trips, and an overview of the statistical results of the repeated-measures ANOVA, which compares the average task frequencies per hour, is provided in Table 3. The front windshield wipers' speed was adjusted with an average frequency of 4.2 times per hour, whilst the radio volume was averagely adjusted 2.2 times per hour. The average frequency with which the radio volume was adjusted is significantly higher than the average frequency with which participants switched radio stations (\(p<0.01\)) or adjusted the rear-view mirror (\(p<0.05\)). Particularly noteworthy is the usage of the front windshield wiper, as its maximum use frequency is relatively high compared to many of the other tasks. This finding can be explained by the fact that some of the participants were unable to figure out how to set the windshield wipers to a proper interval in the unfamiliar car. Therefore, some participants had to constantly trigger the windshield wipers manually, resulting in a maximum of 29 occurrences on a single trip for this task. This can also be seen in Figure 3.  
To get a better overview of the type of tasks that are used relatively frequently, the tasks have been grouped together into several function categories (the overview of all tasks per function is displayed in Table 1). Figure 2 shows the aggregated frequencies for all tasks per function category. Presented are only the function categories for which there were more than ten interactions with any of its tasks. Table 4 comprises the results of the repeated-measures ANOVA to compare the average task frequencies for these function categories. Figure 1: The ten most performed tasks overall, collocating trips made in the familiar and the unfamiliar car. \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & \begin{tabular}{c} **Mean Use** \\ **Frequency** \\ **per Hour** \\ \end{tabular} & \multirow{2}{*}{SD} & \multicolumn{2}{c}{ANOVA} & \multicolumn{2}{c}{**Post Hoc Comparisons**} \\ \cline{3-5}  & **Frequency** & & \(F\) & \(p\) & **with Bonferroni Correction** \\ \hline \hline \begin{tabular}{c} Lights category \\ \end{tabular} & 66.6 & 14.3 & & & \\ \hline \begin{tabular}{c} Windshield category \\ \end{tabular} & 7.2 & 11.0 & & & \\ \hline \begin{tabular}{c} Radio and media category \\ \end{tabular} & 3.3 & 3.9 & & & \\ \hline \begin{tabular}{c} Climate-control category \\ \end{tabular} & 1.9 & 2.3 & & & \\ \hline \
\begin{tabular}{c} Other category \\ \end{tabular} & 0.7 & 1.5 & & & \\ \hline
\begin{tabular}{c} Setup category \\ \end{tabular} & 0.6 & 1.2 & & & \\ \hline \end{tabular}
\end{table} 
Table 4: Repeated-measures ANOVA for the aggregated task frequencies per function category, collocating trips made in the familiar and the unfamiliar car. * \(p<0.10\), ** \(p<0.05\), *** \(p<0.001\). Figure 2: Aggregated task frequencies per function category. Since the direction indicator is part of the lights category, it is not surprising that this function category has the highest average use frequency, which is 66.6 interactions per hour. This is significantly higher than all other categories (\(p<0.001\)). The function categories with the second and third highest use frequencies are the windshield and radio and media categories, with an average of 7.2 and 3.3 interactions per hour, respectively.