What are close calls? A proposed taxonomy to inform risk communication research

•Close calls are important for risk communication; yet, few theoretical frameworks tie them to related research. Candidates are presented here.•Taxonomies can distinguish close calls from related concepts like false alarms, true alarms, and missed alarms. An initial taxonomy is presented.•Close call databases for certain tasks are presented; however, they lack standardization and tools to assist decision makers.•Categorizing specific close call events by their impacts and severity may facilitate risk communication. Real-world examples are offered.•Additional research should stress close call modeling, utility, management, response training, signaling, leveraging, and categorization.

Technology designers and researchers view close calls as an actionable source of information that can be leveraged to increase safety. Organizational representatives responsible for safety examine close call trends to understand their impact on human cognition and to improve risk communication. The relatively few published theoretical investigations of close calls have lacked focus. Attempts to relate close calls to Signal Detection Theory have often neglected the human judgment of event feedback. Furthermore, close call effects can be considered from a variety of perspectives, illustrating the enormity of the problem space. An important first step is to develop a taxonomy and framework that reflects close call impacts, severity, and potential for risk communication. The current article distinguishes close calls from false alarms, specifies a proposed framework for their definition, and demonstrates differences in severity within task domains. The article concludes with a proposed research agenda.