Effects of intermittency of feedback on a compensatory tracking task.

Target intermittence in tracking has been studied as frequency of target presentation at various time intervals. Task efficiency increased as a function of increased frequency of target display in open-loop tracking tasks, where the steady state of presentation resulted in the best performance. The present study examined effects of feedback intermittency in compensatory tracking as a major source of disruption of the motor-sensory feedback process in the closed-loop tracking system. Feedback intermittency is defined as the feedback of momentary sampling of the difference between target movements and the operator's control motion for specified time lengths before being displayed to him in a continuous tracking task. With a random wave pattern of 9.76 cpm, 7 magnitudes of 0.0, 0.2, 0.4, 0.6, 0.8, 1.0, and 1.5 sec. were used to represent various levels of feedback intermittency. Task efficiency decreased as a function of increased magnitudes of intermittency. Results are discussed relative to the difference between target intermittence and feedback intermittency and their effects on different tracking tasks. The findings also establish the concept of feedback intermittency as a disturbing factor in compensatory tracking in degrading the operator's performance.