Effects of Multiple-Signal Discrimination on Vigilance Performance and Perceived Workload

Abstract

Prior vigilance studies have shown that successive monitoring tasks involving absolute judgments are more capacity-demanding than simultaneous tasks which are comparative in nature. Most of these data stem from experiments utilizing simple discriminations and single-target displays, and, consequently, little is know regarding performance on sustained attention tasks with more complex displays. Observers in the present study monitored either one (O-bits display uncertainty), two (1-bit display uncertainty), or four (2-bits display uncertainty) indicators on a simulated aircraft display for the occurrence of critical signals presented in either a simultaneous or a successive format. Results indicated that correct detections declined as display uncertainty increased, and that this effect was more pronounced in the simultaneous format. Moreover, workload scores increased with display uncertainty, particularly in the simultaneous condition. These findings suggest that in more complex monitoring situations in which there is a scanning imperative successive tasks may have an advantage over their simultaneous counterparts.