Cough once for danger: Icons versus abstract warnings as informative alerts in civil aviation

Objective: An experiment investigated the efficacy of auditory icons as warning signals in an aviation context. Background: Iconic signals, such as a cough to signal dangerous levels of carbon monoxide, convey information about the nature of an incident and alert the operator that there is a problem, whereas signals that are arbitrarily associated with a critical incident provide relatively less information. Warning recognition speed and accuracy are likely to be influenced by modality of presentation (visual, auditory, auditory + visual) and task demand (low, high). Methods: The 172 participants completed a computer-based training session and test task that involved responding to abstract or iconic auditory (1 s), visual, or auditory + visual warnings associated with seven critical incidents while performing low- and high-demand concurrent tasks. Results: Significantly fewer training trials were required to learn iconic warnings than abstract warnings. An advantage for iconic warnings persisted into the test phase, evident most consistently as greater warning recognition accuracy. The effect was observed in both high- and low-demand conditions. Auditory abstract warnings, in particular, elicited slow reaction times and poor accuracy. Conclusion: Associations between a small number of meaningful environmental sounds and critical incidents can be learned with ease relative to more abstract associations, although training is required and response times are relatively slow. Application: Sets of distinctive auditory iconic warnings can be designed to alert and inform pilots about non-time-pressured events. Potential applications of language-neutral icons as informative warnings include civil, commercial, and defense aircraft.