Consideration of several mental workload categories: perspectives for elaboration of new ergonomic recommendations concerning shiftwork

In this article, a reflection is presented concerning consideration of several mental workloads in ergonomics to describe work situation. For that, results of three experiments are recalled and put into perspective to understand relationships between mental workload and performance, and between different measures of mental workload. A integrative model IWA for individual – mental workload – activity is presented to explain interactions between task parameters, individual characteristics and contextual characteristics showing relevance to consider all the elements of a work situation to can estimate the more correctly possible mental workload supported by operator. Then, discussion on relevance of mental workload measures permits to highlight the lack of exhaustive measures of different components of mental workload. Finally, methodological propositions with a diagnostic or prognostic approach are presented in order to consider all elements described in model IWA.