Effects of Varying the Threshold of Alarm Systems and Task Complexity on Human Performance and Perceived Workload

Using a dual-task paradigm, we examined how alarm system detection threshold and task complexity affected human performance and perceived workload. We hypothesized that using an alarm system would improve task performance and lower perceived workload, particularly when task complexity was high and at the medium threshold level. Twenty-one students from Old Dominion University participated in this study. Results showed that alarm use improved performance during low task complexity. For high task complexity, improvement was accomplished only when alarm system threshold was low or intermediate. Results also indicated that changing the alarm system threshold affected performance only under high task load conditions. Optimal performance was achieved by setting the threshold of the alarm system at its lowest level. The use of alarms reduced workload under both low and high task complexity levels, but only when the threshold was high.