Effects of Caffeine and Gender on Vigilance and Marksmanship

Sentry duty performance requires both rifle marksmanship accuracy and sufficient attention to detect the infrequent appearance of targets. Research has shown that marksmanship accuracy is in part a function of arm-hand steadiness, that arm-hand steadiness may be better in women than men, and that in men 200 mg caffeine heightens alertness and attenuates vigilance decrements. Study objectives were: (a) evaluate gender differences in speed of target detection and rifle firing accuracy during three hours of simulated sentry duty, and (b) determine if 200 mg caffeine enhances sentry duty performance in women as it has been shown to do in men. Twelve men and 12 women were pre-trained on the Weaponeer M16 Rifle Marksmanship Simulator. During 3-hour test sessions, the participant monitored the target scene of the Weaponeer and fired at targets when they appeared. For both men and women, target detection response time deteriorated with time on sentry duty and vigilance decrements were attenuated by 200 mg caffeine. For men, marksmanship accuracy was constant over time; for women, marksmanship accuracy deteriorated after 1.5 hours.