Workload

The term workload can refer to several different yet related entities. An old definition refers to workload as the amount of work an individual has to do. There is a distinction between the actual amount of work and the individual's perception of the workload. To distinguish the two types, the term 'mental workload' (MWL) is often preferred, clearly indicating the latter type, which refers to the workload experienced by a human, regardless of the task's difficulty. This is because the same underlying task might generate two distinct mental responses and experiences, thus, different cognitive load amounts, even if executed by the same person. Many definitions of mental workload have been proposed in the years. A more recent and operational definition is that "Mental workload (MWL) represents the degree of activation of a finite pool of resources, limited in capacity, while cognitively processing a primary task over time, mediated by external stochastic environmental and situational factors, as well as affected by definite internal characteristics of a human operator, for coping with static task demands, by devoted effort and attention". This definition has emerged from a systematic review of the construct of mental workload by analysing many published research works and all the ad-hoc definitions that have emerged in the last 60 years. It has also been influenced by the Multiple Resource Theory, described below, and the notion of human, multiple resources. The assessment of operator workload has a strong impact on new human-machine systems design. By evaluating operator workload during the design of a new system, or iteration of an existing system, problems such as workload bottlenecks and overload can be identified. As the human operator is a central part of a human-machine system, correcting these problems is necessary to operate safe and efficient systems. An operating budget may include estimates of the expected workload for a specific activity. 'Workload' or 'cognitive load' is often confused with 'cognitive load theory'.