Ergonomic guidelines for traffic sign design increase sign comprehension

Objective: This research directly tests the relationship between comprehension probability of highway signs and the extent to which they comply with three ergonomic principles of design: sign-content compatibility, familiarity, and standardization. Background: A recent study that evaluated comprehension of traffic signs in four different countries showed that comprehension level varies widely and is apparently related to the extent that the sign's design incorporates ergonomic guidelines for good design (D. Shinar, R. E. Dewar, H. Summala, & L. Zakowska 2003). Method: Participants were presented with 30 signs and asked to describe each sign's meaning. They then evaluated each sign in terms of each of three ergonomic principles. In addition, a group of human factors/ergonomics experts evaluated each sign on its standardization and compatibility. Results: There were high correlations between the ratings of the students and the ratings of the experts on compatibility (rho = .94) and on standardiza-tion (rho = .84), validating the use of the students' evaluations of the signs on these variables. There was a great variability in signs' comprehension and high and statistically significant correlations between the comprehension level of each sign and the extent to which it complied with compatibility (R = .76), familiarity (R = .89), and standardization (R = .88) principles. Conclusions: The more signs conform to universal ergonomic principles of good design, the more likely they are to be comprehended by drivers of different cultural backgrounds. Application: Sign design should be guided by established ergonomics principles to enhance comprehension, especially for drivers who have not had any prior encounters with specific signs.