## 3 Results
### Cognitive Design Features  
To determine the cognitive design features which have affected sign comprehension, the Pearson correlation between matching accuracy and matching time, based on traffic sign type and display condition, was obtained. Table 9 showed that cognitive design features were positively correlated to matching accuracy for both regulatory and warning signs, and negatively correlated to matching time for warning signs. Matching accuracy for \begin{table}
\begin{tabular}{l c c c c c c} \hline \hline  & \multicolumn{6}{c}{**Matching Time (In Seconds)**} \\ \cline{2-7}
**Traffic Sign Type** & \multicolumn{2}{c}{**Drivers**} & \multicolumn{2}{c}{**Non-Drivers**} & \multirow{2}{*}{**F-Test**} & \multirow{2}{*}{_p-Value_} \\ \cline{2-2} \cline{5-6}  & **Mean** & **SD** & **Mean** & **SD** & \\ \hline
1. Regulatory & 5.67 & 2.39 & 5.87 & 1.97 & 0.13 & 0.724 \\
2. Warning & 7.35 & 3.84 & 8.16 & 3.29 & 0.78 & 0.382 \\ F-test & 4.13 & & 10.75 & & & \\ \(p\)-value & 0.047 * & & 0.002 * & & & \\ \hline \hline \end{tabular}  
* values indicate statistical significance at \(p<0.05\).  
\end{table} 
Table 7: Matching time of drivers and nondrivers vs. traffic sign types. warning signs produced the highest Pearson correlation value (\(r=0.703\)) when correlated to concreteness. On the other hand, semantic distance obtained the highest correlation value (\(r=0.777\)) for regulatory signs in the matching accuracy. Familiarity also had a positive relationship with matching accuracy, which was also a good predictor for comprehension, especially when familiar symbols were used. For matching time, familiarity was the best predictor for warning signs (Table 9). To determine the relationship between cognitive design features and display condition, Pearson correlation was also obtained between matching accuracy and matching time. For signs displayed in symbols, the results showed that cognitive design features were positively correlated to matching accuracy, and negatively correlated to matching time. Matching accuracy of signs displayed in symbols obtained the highest Pearson correlation value (\(r=0.801\)) when correlated to semantic distance, while matching time had the highest Pearson correlation value (\(r=-0.440\)) when correlated to familiarity (Table 10). On the other hand, cognitive design features were not correlated to matching accuracy and matching time when text was included in the signs. The results suggested that cognitive design features were more relevant to signs displayed in symbols. To analyze the cognitive design features of each traffic sign, Table 11 shows the signs with the highest and lowest ratings based on cognitive design features. \(\bigtriangleup\) \"Give way at intersection ahead\" received the lowest concreteness and complexity rating with 2.53 and 2.50, respectively. The participants perceived the sign as somewhat abstract and moderately complex. \(\bigcirc\) \"Speed derestriction\" also received the lowest rating in the semantic distance with 2.72, since the design of the icon was far from its intended meaning. Among the signs that received the lowest design evaluation, \(\bigcirc\) \"Speed derestriction\" also received the lowest rating in familiarity at 2.40, since none of the participants matched it correctly, which might be because of the familiarity factor. For the highest ratings, \"Fasten Seatbelt\" was rated as definitely concrete, with a rating of 4.63, which also received a high matching accuracy of 98%. The sign that was rated as simple was \(\bigcirc\) \"Stop\", with a rating of 4.68 and a matching accuracy of 95%. \(\bigcirc\) \"No Stopping Anytime\" was rated as very strongly related