The Effects of Participatory Mode and Task Workload on the Detection of Dynamic System Failures

The ability of operators to detect step changes in the order of control dynamics is investigated as a joint function of a) participatory mode, whether subjects are actively controlling those dynamics or are monitoring an autopilot controlling them, and b) concurrent task workload. Five subjects either tracked or monitored the system dynamics on a two-dimensional pursuit display under single task conditions and concurrently with a "subcritical" tracking task at two difficulty levels Detection performance was faster and only slightly less accurate in the manual as opposed to the autopilot mode. Performance in each mode was derogated by the concurrent tracking requirement, but not by increases in loading task difficulty. Further analysis indicated that manual superiority was attributable to the additional proprioceptive information resulting from operator-control adaptation to the system change.