Cognitive Design Features on Traffic Signs

Abstract

The success of effective communication of traffic sign messages to road users may not only relate to the user characteristics but also the signs themselves. The purpose of this experiment was to examine the cognitive design features of 120 Mainland China traffic signs. The features included familiarity, concreteness, simplicity, meaningfulness, and semantic closeness. Forty-one Hong Kong Chinese engineering undergraduates, who have never taken any driving tests, nor possessed any driving licenses in any places, voluntarily participated in this experiment. For each sign, subjects were asked to give subjective ratings between 0 to 100 points for familiarity (0 = very unfamiliar, 100 = very familiar), concreteness (0 = definitely abstract, 100 = definitely concrete), simplicity (0 = very complex, 100 = very simple), meaningfulness (0 = completely meaningless, 100 = completely meaningful), and semantic closeness (0 = very weakly related, 100 = very strongly related). With the exception of familiarity, the mean ratings on the other four sign features for all signs were above the midpoint (50) of the 0-100 rating scale. The below the mid-point rating (43.87) on familiarity showed that the subjects were not quite familiar with the chosen Mainland China traffic signs. The mean ratings for concreteness, simplicity, meaningfulness, and semantic closeness for all signs were 62.60, 75.81, 69.37, and 68.44, respectively, illustrating that the selected traffic signs were perceived to be moderately concrete, simple and meaningful, and related to their intended meanings. Significant and positive relationships were found amongst the cognitive sign features of familiarity, concreteness, meaningfulness, and semantic closeness. Other than with familiarity, simplicity did not correlate with the other four features. The box plot may be used as a tool for identifying unusual signs for in-depth analysis and for guiding designers to develop new traffic signs at the design stage. The results suggested that cognitive design features are useful for designing more user-friendly traffic signs, which should transmit clear messages about road conditions ahead at the right time to road users. Further research efforts will be given in investigating the effect of sign features on sign comprehension. are usually conveyed with the use of symbols, words, or a combination of both. There are some studies addressed to traffic signs on, for instance, sign visibility (2), sign luminance (3), sign conspicuity (4), and sign comprehensibility (5). The success of effective communication of sign messages to road users may not only relate to the user characteristics but also the signs themselves. Instead of considering icon features that are self-evident (e.g. color and shape) or those that can be identified only in relation to other icons (e.g. distinctiveness), the icon features like familiarity, concreteness, complexity, meaningfulness, and semantic distance are of central concern in icon research (6). Familiarity is defined in terms of the frequency with which icons had been encountered by subjects. Icons are regarded as concrete if they depict real objects, materials, or people; those that do not depict real objects are considered as abstract. Icons are regarded as complex if they contain a lot of detail or are intricate, and they are simple if they only contain few elements or little detail. Meaningfulness refers to how meaningful the judges perceive icons to be. Semantic distance is a measure of the closeness of the relationship between what is depicted in an icon and the function it is intended to represent. The interrelationships between icon familiarity, concreteness, complexity, meaningfulness, and semantic distance had been examined with two hundred and thirty-nine icons which included computer icons, traffic and public information icons, industrial icons, symbols for household goods (6). Without consideration of the subject experience of the icons, the results revealed that icon familiarity, concreteness, meaningfulness, and semantic distance were strongly interrelated, whereas icon complexity did not correlate closely with other features. As the frequency of use of an icon would continually reinforce the perceived semantic closeness of the icon (7), the results of interrelationships amongst icon features would be different for naive and experienced subjects. This experiment aimed to study the cognitive design features of traffic signs with prospective drivers. Mainland China traffic signs were selected and tested in this experiment to reduce any influence of possible daily encounters or prior experience for the subjects. To build more consistent order of response scales amongst the five sign features, the terms 'complexity' and 'semantic distance' used in (6) were revised as 'simplicity' and 'semantic closeness', respectively in this study. The collected data were processed and analyzed with appropriate statistical techniques. The results of this experiment should provide useful information and the basis for recommendations for designing more user-friendly traffic signs.