Comprehension of traffic signs with symbolic versus text displays

Objective: To evaluate the benefits of text and symbolic displays in highway signs relative to their familiarity on their comprehension speed and accuracy. Background: A recent study that evaluated the influence of ergonomic principles-familiarity, standardization, and symbol-concept compatibility-on traffic sign comprehension showed that comprehension is highly correlated with the compliance with these ergonomic design principles (Ben-Bassat & Shinar, 2006). As an alternative to existing unfamiliar symbolic signs we tested the effect of adding text. Method: Drivers were presented with 30 traffic signs varying in their level of familiarity in three display conditions: standard symbol-only, text-only, and symbol + text. Speed and accuracy of comprehension were recorded. Results: Display condition and familiarity significantly affected both correctness of the answers and reaction time. Correctness improved when the symbol was shown with text, especially when the sign was less familiar. Conclusions: Adding text improves the comprehension and reduces the time it takes to comprehend the sign, especially of unfamiliar signs. Application: Adding text could be a simple solution to making (unfamiliar) signs more understandable to a greater segment of the driving population without compromising comprehension time, thereby increasing traffic safety.