Investigating users’ mental representation of likelihood alarm systems with different thresholds

摘要

Graded warnings; trust; compliance and reliance; decision-making; signal detection theory%This study investigated effects of threshold setting in likelihood alarm systems (LASs) on safety, performance and participants’ mental representation of LASs. Three LASs were compared under two workload conditions. LASs had the same lower (first) threshold separating non-alerts from warnings but differed with regard to their higher (second) threshold dividing warnings from alarms. Behaviour, performance and trust were assessed. Participants of all three conditions responded to almost every alarm but only to parts of the warnings. Threshold setting affected safety, as the most liberal second threshold led to the highest joint humanu0001machine sensitivity. Increasing workload decreased concurrent task performance. A negative correlation of trust in warnings and response rates to warnings reflected reliance and implies a mental representation of graduation of non-alerts. Results suggest that LAS threshold setting allows a precise guidance of users’ behaviour and show the importance of knowledge regarding users’ mental representation for the design of LASs.