Performance During a 3-Hour Simulated Sentry Duty Task Under Varied Work Rates and Secondary Task Demands

The performance of 14 soldiers was evaluated during 3 hr of simulated sentry duty when (a) the primary work rate was varied and (b) participants were required to intermittently perform a simple secondary task. Performance measurements included latency to detect a target, number of correct target detections, correct friend versus foe identification, targets hit, and latency to respond to the presentation of a continuous tone (secondary task). Activity monitors measured motor activity during study participation. During higher work rate sessions, participants responded to the appearance of a target more quickly, discriminated friend from foe more accurately, and hit more foe targets. The addition of a simple auditory task to the primary task did not affect performance on any of the sentry duty measures. These findings demonstrated that moderate increases in task engagement, or work rate, improved most performance metrics on a long duration (3-hr), militarily relevant vigilance task.