ABSTRACT
Quantitative models of the human operator may provide insights into basic properties of human performance. The ability to derive transfer functions for human operators would greatly facilitate the ability to predict the performance of human—machine systems. Applying the analytical power of linear analysis to those behavioral contexts where they are appropriate may lead to important theoretical and practical insights about human performance. Although the human tracker is clearly nonlinear, linear analysis can provide important insights into human performance and linear models may be able to give reasonable predictions for some situations. The human transfer function appears to consist of a gain, a lag, or an integrator at higher frequencies, and a time delay. The frequency response of the human element changes with changes in the plant dynamics. The crossover model suggests that there is a greater likelihood of finding invariance at the unit of human-environment systems.
