The Relationship between Mental Workload and Situation Awareness

Mental workload and situation awareness are both outgrowths of the practical need to assess operators' performing and managing dynamic complex tasks. Mental workload refers to the cost placed on the human operator's cognitive processing abilities by performing the required task-related mental processing. Situation awareness is the operator's apprehension of the current situation. Common goals of designing a new system or modifying an existing one are often to reduce the operator's mental workload while increasing the operator's situation awareness. However, the empirical database obtained from concurrent evaluation of mental workload and situation awareness demonstrates that the two measures generally do not co-vary in such a simple fashion. The lack of a single straightforward correlation could be interpreted as an indication that mental workload and situation awareness must be considered independent of each other. However, parsing the available studies into sub-categories based on the type of manipulation that was investigated allows some possible relationships between mental workload and situation awareness to emerge. This suggests that researchers should continue to examine the relationship between these concepts and system evaluators should not consider mental workload or situation awareness in isolation from the other.