Supporting change detection in complex dynamic situations: Does the CHEX serve its purpose?

Change detection is required in monitoring and managing complex situations such as air traffic control. Considering that change blindness - the incapacity to detect changes in a visual scene - is a considerable source of human errors and that most studies on change detection have involved static visual scenes, it is crucial to evaluate existing tools designed to help this cognitive function in complex dynamic situations. The goal of the present study was to determine the efficacy of the Change History Explicit (CHEX) - a tool already proven effective when explicit change detection is the only task to execute - when change detection is implicit and intrinsic to a more complex task. Results revealed that the CHEX failed to improve implicit change detection when this task was embedded in a threat-evaluation and weapon-assignment (TEWA) task. Moreover, TEWA performance was hindered and mental workload was perceived as higher when the CHEX was available. Even when the information load imposed by the CHEX was reduced, the tool remained ineffective. This suggests that the nature of the change detection task should be taken into account when designing a decision support system.