BLINKS, SACCADES, AND FIXATION PAUSES DURING VIGILANCE TASK PERFORMANCE: I. TIME ON TASK

Operators of complex equipment increasingly are spending more time monitoring computer controlled devices rather than having hands-on control. The operator intervenes in system operation under unusual conditions or when there is a computer malfunction. The operator's task thus becomes a "vigilance" task, one requiring attention to monitoring equipment with little need for action. An individual's ability to maintain vigilance is easily compromised, with time-on-task (TOT) a major detractor of performance. This research asks if gaze control measures can be used to reflect and predict periods of impaired vigilance. The results of this study clearly demonstrate that a number of aspects of eye movements and eye blinks show significant TOT effects. These effects are more likely to be associated with short periods of attentional lapses or "microsleep" than with more tonic changes in alertness level. The literature dealing with indicants of fatigue and time-on-task effects is reviewed. The study evaluated aspects of blinking and eye movements in subjects performing an air traffic control simulation task. Subjects performed the task for a 2-hour period on 3 separate occasions. Significant increases in blink frequency, blink closing duration, blink flurries, eye closures and fixation pause were obtained as well as similar effects for derivative measures. Though the current data was collected through electrodes attached to the participant, much of the information can be acquired with remote monitoring technologies. This makes possible the application of such measures in a field setting where subjects are required to work on a display terminal.