Discrimination among sign and label warning signal words

Signal words are commonly used in warnings to quickly communicate potential hazards. Current standards and guidelines define the terms DANGER, WARNING, CAUTION, and NOTICE as denoting decreasing hazard levels, respectively. This study examined whether definitions assigned to these words coincide with people's understanding of them. Seventy-two participants attempted to match published definitions to the terms. Additionally, they rated the terms on various dimensions (e.g., hazardousness, understandability). The results showed that people differentiate DANGER and NOTICE but less clearly discriminate between WARNING and CAUTION. The term DEADLY, a proposed higher level signal word, was perceived as connoting the greatest hazard. Implications for warning design are discussed.