Abstract
Different types of alarms and events can affect an operator's trust in an alarm system. This paper presents an experiment in which we examined the effect of two types of alarm systems (two-state and three-state alarms) on trust, alarm compliance, and diagnosis for two types of faults differing in complexity. Undergraduate university students using a simplified process control microworld simulation served as participants. The findings from this research showed participants performed better and had more trust in three-state alarms compared to two-state alarms. This paper discusses these findings in terms of their theoretical implications and practical applications to improving the efficiency and effectiveness of alarm systems in nuclear power plant operations.