ABSTRACT
The study of mental load focuses on the cost of mental operations, and the constraints that are imposed by these costs on the ability of a performer to cope with the demands of a task that he or she is given to perform. Experimental research has identified three types of cost functions, each accompanied with a set of measurement techniques: behavioural (the cost of load to performance), subjective (the conscious appraisal of load) and physiological (state variables and specific activities associated with the work of the mind). For some tasks, load measures obtained by different methods covary, while in others they dissociate. This chapter reviews the different measurement approaches and discusses the theoretical debates that surround this research. The major topics addressed are the definition of mental operations, capacity versus interference models, modes of processing, acute peaks versus sustained attention task, and voluntary control of attention. The chapter is concluded by an outline of an emerging conceptual framework, and delineates directions for future research.
