Standards of Acceptable Load in ATC Tasks

Abstract Mental load in ATC tasks is described as the brain controlling the controller's controlling performance. A moment of conscious brain control is put forward as a unit to quantify this kind of mental load. New action programs are supposed to require conscious brain control at every step of their execution; with routine this would be less and less the case. The duration of a moment of conscious control varies according to the complexity of the control to be exercised and the number of considerations which have to be taken into account. Propositions are made on how to think about selective attention, identification and cognitive processes in terms of executing programs. A job description method is put forward in terms of such executing programs. Why moments of conscious brain control as units are more suited to the problem of mental load than are units like bits, choices and decisions is discussed. Experiments are described with physiological and psychological variables as a function of the number of moments of conscious brain control per minute.