Human Frequency Response as a Function of Visual Feedback Delay

Abstract

This paper uses a light-matching tracking study to determine the human frequency band pass characteristics in the presence of significantly large external transmission delays which are introduced into the stimulus-response information loop. Such delays occur in real time operation of vehicles and other equipment which is at some distance from the operator (near earth or deep orbit, surface of the moon, etc.). When information in the visual sensory channel is delayed because of transmission times between man's controlling action and the displayed results, this interacts with the relatively short normal delay of the other sensory feedback loops such as tactual and kinesthetic information loops, causing substantial phase interference problems between otherwise in-phase parallel sensory information channels. A representative model was used for the human transfer function for the system studied, which matched the experimental data reasonably well. The maximum frequency at which a person could meaningfully accept and act on random inputs (where the cut-off point was defined as the 3 db down point) is f_co = 0.16/(T + 0.15)^0.85 for a T second transmission delay.