When there are conflicting views within a client body on the merits of an information-design product, judicious testing may provide a way out of a difficult situation. The process of discussing and agreeing upon that testing may itself provide useful clarification of the brief. This article discusses the testing of how well some warning signs stand out and how well they can be discriminated from each other. A railway authority wanted to replace remote area signalmen with stationary warning boards, but the union objected to the original design.Laboratory-based testing was used to answer questions about conspicuity and discriminability and to evaluate a proposed solution.