Prohibitive pictorials

To indicate a prohibited activity, pictorials are frequently overlaid with a red circle and 45° left-to-right slash. Previous research suggests that the combination of the slash and symbol may affect the overall identifiability of the warning. The purpose of the present research was to determine whether people's judgments of four types of the circle-slash (a slash over the symbol, a slash under the symbol, a partial slash, and a translucent slash) would differ in perceived effectiveness. Sixteen pictorials with semantically different message content (e.g., NO TRUCKS, DO NOT CLIMB TOWER), in both left-facing and right-facing orientations were viewed by 60 participants. The results revealed that the over and under slashes were preferred to the translucent or partial slashes. Both orientation and slash type influenced preference for a subset of nonsymmetrical symbols. Some of the pictorials with the over slash were given lower evaluations when critical features were concealed. The general preference for the over and under slashes may be due to familiarity and its concordance with Gestalt principles of good figures. Implications for the development of prohibitive pictorials are discussed. Relevance to industry Pictorials are increasingly being used to communicate safety information in cases where the target audience may use different languages. The present research examines different versions of the circle-slash negation symbol for the purpose of determining when critical pictorial elements may be obscured. Implications for pictorial recognition are discussed.