Evaluating the Usability of Common Warnings across Industries Using the System Usability Scale

This study evaluated people’s perceived usability of warning signs and labels using the System Usability Scale (SUS), to understand how textual and visual factors of warnings contribute to SUS scores. 30 warning signs/labels across various industries were selected and 135 participants evaluated these warnings on their usability and familiarity. Each warning’s textual and visual complexity was also assessed. The resulting SUS scores for the warnings covered a broad range (min = 26.1, max = 92.4). Familiarity with the system and the number of words on the warning significantly correlated with SUS scores. Warnings with higher lexical density, a measure of how informative a written text is, related to higher SUS scores. There was no significant relationship between warnings’ visual complexity and SUS scores. The results suggest that the SUS might prove to be a simple and useful way to measure the usability of warnings.