ABSTRACT
Operator state describes the general condition of a human operator interacting with a system. The concept includes behavioral activity, physiological patterns, and psychological states, and is strongly context dependent (Pleydell-Pearce et al., 1999). Well-designed IASs should monitor operator state and enable flexible task allocation between the operator and the machine to reduce operator workload and fatigue. Well-designed systems should automatically assign tasks to the machine during periods of high stress (i.e., overload), and should reengage operators during periods of underload. IASs can either return tasks to active operator control, keeping the operator in-the-loop, or provide stimuli to refocus supervisory operator attention, keeping the operator on-the-loop (Chen and Barnes, 2014). An ideal IAS design allocates tasks collaboratively while emphasizing operator needs.
