vigilance
n. a state of extreme awareness and watchfulness directed by one or more members of a group toward the environment, often toward potential threats (e.g., predators, intruders, enemy forces in combat). In animal behavior, vigilance increases in females after the birth of their young and in response to alarm calls. In large groups, there can be a division of labor, with individuals taking turns in vigilance. In a military context, vigilance tasks (e.g., sentry duty, ship and air traffic control, antiaircraft and missile defense tracking) demand maximum physiological and psychological attention and readiness to react, characterized by an ability to attend and respond to stimulus changes for uninterrupted periods of time. This level of vigilance can produce significant cognitive stress and occasional physiological stress reactions. Also called vigilant attention. Compare ambient awareness; situation awareness.
—vigilant
adj.