Effect of Variable Feedback Delay on Visual Target-Acquisition Performance

Traditionally, private communication channels with stable characteristics have been used in teleoperation situations. However, recently there have been a few attempts at using public communication channels such as the Internet. In spite of their convenience, very little is known about the effect of the variable delays inherent in this type of channel on motor performance. In this thesis, we provide empirical data on the impact of variable feedback delays on a 3D visual target-acquisition task performed in a virtual environment. Target size, distance between targets, mean feedback delay, and feedback-delay variability were manipulated and the number of errors and movement time (MT) were measured. Results showed that feedback-delay variability affected the closed-loop part of visual target-acquisition movements, even though its effect was weaker than the effect of mean feedback delay. Our results advise against using techniques that reduce feedback-delay variability at the expense of increasing mean feedback delay. In addition, we found that target size was critical for visual target-acquisition performance in the presence of feedback delays and this should be considered when designing teleoperation situations. Issues associated with studying feedback-delay variability are identified and lines of future research are suggested