## 4 Discussion
Traffic signs which received the lowest ratings in cognitive design features were mostly in a symbol format. For instance, \(\mathbf{\triangle}\) \"Give Way at Intersection Ahead\" and \(\mathbf{\check{Q}}\) \"Speed derestriction\" both received the lowest ratings in concreteness, complexity, and familiarity. Consequently, these signs were also poorly comprehended; \(\mathbf{\triangle}\) \"Give Way at Intersection Ahead\" obtained a 17% matching accuracy, while none of the participants matched the \(\mathbf{\check{Q}}\) \"Speed derestriction\" correctly. In terms of semantic distance, \(\mathbf{\check{Q}}\) \"Speed derestriction\" also received the lowest rating at 2.72, the only traffic sign that obtained a semantic distance rating of below 3.0. The low rating can be attributed to its design which was very far from its intended meaning. For instance, \(\mathbf{\check{Q}}\) \"Speed derestriction\" can be confused with the symbolic \"No-entry\" sign, which was very far from its referent name of end of speed restriction. It should be noted that one important criterion for good sign design is its ability to induce comprehension of its meaning when being encountered for the first time (e.g., seeing the sign by nondrivers for the first time). However, even those with driving experience found difficulty in comprehending the meaning of this sign. On the contrary, the \(\mathbf{\check{\mathsf{R}}}\) \"No Right Turn\" sign was comprehended well, obtaining a 98% matching accuracy. This is because the comprehension of drivers focuses on how consistent the sign symbols are to their cognitive expectations [18]. [PERSON] [44] compared several alternative symbols used to signify work zones and found that symbols with a good physical resemblance to what they are meant to signify were all well understood, even when the details of these symbols were different. In contrast, when the intended message was different to how it was conveyed symbolically, all proposed alternative symbols were not clearly understood [44]. Therefore, the closer the semantic meaning of the sign, the higher the comprehension level. Furthermore, the cognitive design feature ratings were also seen to be highest in semantic distance and concreteness. This was further validated by multiple regression analyses wherein semantic distance was associated with matching accuracy, while concreteness and familiarity were significant for predicting matching time (Table 12). Interestingly, semantic distance alone contributed 59.53% in predicting matching accuracy, but semantic distance was not significant in predicting matching time. On the other hand, concreteness can explain 38.28% of the variance, while familiarity contributed 4.68% in predicting matching time. Thus, to improve comprehension performance, semantic distance, concreteness, and familiarity are the key cognitive design features that must be considered by designers. Specifically, this study found that semantic distance is the most significant predictor for matching accuracy, which was also the result obtained by other traffic comprehension studies [3; 45]. For matching time, concreteness and familiarity are the best predictors, especially for warning signs, but also for signs displayed in symbols. When changing the symbol was deemed impractical (e.g., when it was already consistent with international code), it is recommended to add text above or below the symbol to give drivers more opportunities to understand the meaning and to retain the information in memory [11]. Interestingly, signs displayed in text using the local language resulted in better comprehension compared to other display conditions [11]. In this study, signs in textual format were comprehended well by the Filipino participants since they can easily understand the texts which all were written in English.