Warning signal words: connoted strength and understandability by children, elders, and non-native English speakers

Signal words, such as DANGER, WARNING and CAUTION, are commonly used in sign and product label warnings for the purpose of conveying different levels of hazard. Previous research has focused on whether people's perceptions of connoted hazard are consistent with the levels suggested by design standards and guidelines. Most investigations have used college students to evaluate the terms; other populations who may be at greater risk have not been adequately studied. One purpose of the present research was to determine whether young children, the elderly, and non-native English speakers perceive similar connoted hazard levels from the terms as undergraduates and published guidelines. A second purpose was to assess the terms' comprehensibility using various metrics such as missing values (i.e. ratings left blank) and understandability ratings. A third purpose was to develop a list of potential signal words that probably would be understandable to members of special populations. In the first experiment, 298 fourth- to eighth-grade students and 70 undergraduates rated 43 potential signal words on how careful they would be after seeing each term. The undergraduates also rated the terms on strength and understandability. In the second experiment, 98 elders and 135 non-native English speakers rated the same set of terms. The rank ordering of the words was found to be consistent across the participant groups. In general, the younger students gave higher carefulness ratings than the undergraduates. The words that the younger children and the non-native English speakers frequently left blank were given lower understandability ratings. Finally, a short list of terms was derived that 95% or 99% of the youngest students (fourth- and fifth-graders) and 80% of the non-native English speakers understood. Implications of hazard communication are discussed.