## 1 Introduction
[10] mentioned that when both symbols and verbal codes are provided, memory quality is improved because of the synthesis of the details of the symbols and texts. In the comprehension of traffic sign context, [PERSON] and [PERSON] [11] found that adding text to symbols can improve the driver's comprehension levels and reduce the time it takes to comprehend traffic signs. Designing traffic signs also requires the standardization of shapes so that various signs can easily be recognized and can provide immediate information to drivers and pedestrians. For example, the circle symbol is mainly used for regulatory signs that inform road users of traffic laws and regulations, which, if disregarded, will constitute an offense [12]. Examples of regulatory signs are those identified as priority (obligation to give way at intersections), speed (speed limit limitations), direction (indicating the direction to follow), prohibitive (prohibition of movements at intersections), parking (control of vehicle parking), and miscellaneous (not covered in other categories, such as no blowing of horns) [12]. The equilateral triangle symbol with one point vertically upward is used for warning signs. Warning signs communicate information regarding potential hazards and intend to help reduce or eliminate the associated risks [13]. For example, the horizontal alignment signs assist drivers in negotiating curves safely and to indicate the direction and approximate degree of the turn required [14]. These characteristics are an important consideration in designing regulatory and warning signs to convey the intended information. When a regulatory or warning sign does not clearly convey its intended information, the rate of comprehension is relatively low, ranging from 17 to 37 percent [15]. Thus, most of these signs are poorly understood [16], while some even having their meaning perceived as the opposite of the true meaning [17; 18; 19]. In a study by [PERSON] and [PERSON] [20], drivers' comprehension of warning signs, like crossroads, school crossings, and sharp curves, showed that only 9% of drivers could comprehend the correct sign. Also, drivers routinely have difficulties in understanding the meaning of warning signs, such as'slippery when wet', 'road narrows','steep descent', 'pavement ends', and 'truck crossing', with correct response rates ranging from 6 to 40% [21; 22; 23]. [PERSON] et al. [24] also found low comprehension scores for 20 regulatory signs. To improve comprehension, these 20 signs were redesigned using ergonomic design principles and obtained significantly higher comprehension level ratings, which is relevant in conveying safety information. To standardize safety signs and safety markings conveying safety information, the International Organization for Standardization (ISO) developed ISO 3864-1:2011 [25]. ISO 3864-1:2011 established the safety identification of colors and design principles to be used in workplaces and public areas for the purpose of accident prevention, fire protection, health hazard information, and emergency evacuation. This standard also describes how symbols should be displayed with supplemental text, multiple images for more than one potential hazard, and the safe viewing distances for compliant signs and labels. Aside from considering sign features that are self-evident (e.g., colors and shapes), or those that can be identified only in relation to other icons (e.g., distinctiveness), icon features such as familiarity, concreteness, complexity and semantic distance are of central concern in traffic sign research [26]. Familiarity is defined as the frequency of encounter or use in daily lives. According to [PERSON] [27], signs that are familiar would be better comprehended by users. Concreteness means that the sign depicts objects which have obvious connections with the real-world--better signs are more concrete, whereas ambiguous signs are difficult to understand [28].