A quantitative description of the human information processor is necessary for predicting operator workload and performance from the simulated task time line data created by task network models and related methods. Although many models of workload exist, few appear to be well grounded in theory or to provide a satisfactory basis for a quantitative model of operator load. Adherents of both time- and intensity-based models of operator load individually claim success for their methods, which might suggest that both factors are operating in determining operator workload and performance. This paper describes a study that explicitly examines the relationship between a time-based factor and an intensity-based factor within a simulated air traffic control environment. A model is devised that posits that the load on the human information-processing system results directly from the ratio of the time necessary to process the required information to the time allowable for making a decision. This ratio, which can be identified with time pressure, determines subjective estimates of workload as well as operator performance. The model is tested against the data from the air traffic control simulation.
Abstract